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Home / DTC / P1745 — Tcu k line

P1745 — Tcu k line

Detailed page for trouble code P1745.

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Code

P1745

DAEWOO P — Powertrain

Tcu k line

Brand: DAEWOO
Type: P — Powertrain
Views: UK: 18 EN: 32 RU: 21
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Open or short in K-line wiring between diagnostic connector and TCU
  • Corroded, loose or damaged connector pins at TCU or DLC (data link connector)
  • Blown fuse or poor ignition/switched power affecting communication circuits
  • Faulty TCU (internal communication circuitry)
  • Interference from aftermarket electronics or improper grounding
  • Faulty diagnostic tool or improper connection

Symptoms

  • Unable to read or clear transmission codes with a scan tool
  • Transmission may default to limp/backup mode or shift irregularly
  • MIL (check engine light) or transmission warning lamp may be illuminated
  • Intermittent or no response when attempting TCU diagnostics
  • Other module communication errors present on scan tool

What to check

  • Verify battery voltage and good, stable power/ground before testing communication
  • Scan vehicle and record all stored/current codes and freeze frame data
  • Visually inspect DLC, TCU connectors and wiring for corrosion, bent pins or damage
  • Verify relevant fuses and ignition-switched power circuits
  • Check for other network/module communication DTCs that may indicate broader bus issues
  • Use a known-good scan tool or adapter to rule out tool incompatibility

Signal parameters

  • K-line idle state: should present pull-up behavior and show recognisable idle voltage with ignition ON (varies by vehicle)
  • When a diagnostic session is requested, K-line should show serial communication pulses (use scope or serial monitor)
  • Open circuit: no pulses and no voltage change when communicating
  • Short to ground: voltage pulled low or stuck low, preventing communication
  • Short to battery: line held high, no modulation during communication attempts

Diagnostic algorithm

  1. Retrieve and record all DTCs from all modules. Note if other communication U-codes are present.
  2. Verify battery voltage and inspect fuses related to TCU and diagnostic circuits; replace if blown.
  3. Visually inspect the DLC and TCU connectors for corrosion, bent pins, moisture or damaged insulation. Repair as needed.
  4. With ignition ON (engine off), measure voltage at the K-line pin at the DLC and at the TCU connector. Compare behavior while initiating communication with a scan tool.
  5. Check continuity of the K-line between the DLC and TCU (ignition OFF). Repair any open or high-resistance wiring.
  6. Check for shorts: measure resistance from K-line to ground and to battery (ignition OFF) to detect shorts to ground or power.
  7. If available, use an oscilloscope to observe waveform on K-line while attempting communication; look for proper serial pulses vs. noise/flatline.
  8. Disconnect non-essential modules or aftermarket devices that share wiring or grounding to identify interference sources.
  9. If wiring and connectors test good but problem persists, consider substituting a known-good TCU (when available) or have TCU bench-tested/repaired by a qualified specialist.
  10. After repair, clear codes and verify stable communication and proper transmission operation on road test.

Likely causes

  • Damaged or disconnected K-line connector at TCU
  • Corroded pins at DLC preventing signal reach
  • Broken wire or short to ground on K-line
  • Failed TCU communication driver

Fault status

⚠️ Status
TCU K-line communication fault detected: the transmission control unit is not responding or the K-line signal is missing/distorted. This indicates an issue with the K-line wiring/connector, power/ground, the TCU communication circuit, or external interference.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1.0-3.0 hours

Similar codes

U0100 U0073 U0121 P0603 P0700
Repair manuals

Manual library for DAEWOO

75

Browse 75 DAEWOO manuals: repair procedures, diagnostics, wiring diagrams, component locations, service data and Labor Times by year, model and trim.

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Code

P1745

FORD P — Powertrain

Transmission system problems

Brand: FORD
Type: P — Powertrain
Views: UK: 27 EN: 38 RU: 31
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Open or short in K-line wiring between diagnostic connector and TCU
  • Corroded, loose or damaged connector pins at TCU or DLC (data link connector)
  • Blown fuse or poor ignition/switched power affecting communication circuits
  • Faulty TCU (internal communication circuitry)
  • Interference from aftermarket electronics or improper grounding
  • Faulty diagnostic tool or improper connection

Symptoms

  • Unable to read or clear transmission codes with a scan tool
  • Transmission may default to limp/backup mode or shift irregularly
  • MIL (check engine light) or transmission warning lamp may be illuminated
  • Intermittent or no response when attempting TCU diagnostics
  • Other module communication errors present on scan tool

What to check

  • Verify battery voltage and good, stable power/ground before testing communication
  • Scan vehicle and record all stored/current codes and freeze frame data
  • Visually inspect DLC, TCU connectors and wiring for corrosion, bent pins or damage
  • Verify relevant fuses and ignition-switched power circuits
  • Check for other network/module communication DTCs that may indicate broader bus issues
  • Use a known-good scan tool or adapter to rule out tool incompatibility

Signal parameters

  • K-line idle state: should present pull-up behavior and show recognisable idle voltage with ignition ON (varies by vehicle)
  • When a diagnostic session is requested, K-line should show serial communication pulses (use scope or serial monitor)
  • Open circuit: no pulses and no voltage change when communicating
  • Short to ground: voltage pulled low or stuck low, preventing communication
  • Short to battery: line held high, no modulation during communication attempts

Diagnostic algorithm

  1. Retrieve and record all DTCs from all modules. Note if other communication U-codes are present.
  2. Verify battery voltage and inspect fuses related to TCU and diagnostic circuits; replace if blown.
  3. Visually inspect the DLC and TCU connectors for corrosion, bent pins, moisture or damaged insulation. Repair as needed.
  4. With ignition ON (engine off), measure voltage at the K-line pin at the DLC and at the TCU connector. Compare behavior while initiating communication with a scan tool.
  5. Check continuity of the K-line between the DLC and TCU (ignition OFF). Repair any open or high-resistance wiring.
  6. Check for shorts: measure resistance from K-line to ground and to battery (ignition OFF) to detect shorts to ground or power.
  7. If available, use an oscilloscope to observe waveform on K-line while attempting communication; look for proper serial pulses vs. noise/flatline.
  8. Disconnect non-essential modules or aftermarket devices that share wiring or grounding to identify interference sources.
  9. If wiring and connectors test good but problem persists, consider substituting a known-good TCU (when available) or have TCU bench-tested/repaired by a qualified specialist.
  10. After repair, clear codes and verify stable communication and proper transmission operation on road test.

Likely causes

  • Damaged or disconnected K-line connector at TCU
  • Corroded pins at DLC preventing signal reach
  • Broken wire or short to ground on K-line
  • Failed TCU communication driver

Fault status

⚠️ Status
TCU K-line communication fault detected: the transmission control unit is not responding or the K-line signal is missing/distorted. This indicates an issue with the K-line wiring/connector, power/ground, the TCU communication circuit, or external interference.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1.0-3.0 hours

Similar codes

U0100 U0073 U0121 P0603 P0700
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Code

P1745

JAGUAR P — Powertrain

Pressure Regulator 1

Brand: JAGUAR
Type: P — Powertrain
Views: UK: 28 EN: 44 RU: 35
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Open or short in K-line wiring between diagnostic connector and TCU
  • Corroded, loose or damaged connector pins at TCU or DLC (data link connector)
  • Blown fuse or poor ignition/switched power affecting communication circuits
  • Faulty TCU (internal communication circuitry)
  • Interference from aftermarket electronics or improper grounding
  • Faulty diagnostic tool or improper connection

Symptoms

  • Unable to read or clear transmission codes with a scan tool
  • Transmission may default to limp/backup mode or shift irregularly
  • MIL (check engine light) or transmission warning lamp may be illuminated
  • Intermittent or no response when attempting TCU diagnostics
  • Other module communication errors present on scan tool

What to check

  • Verify battery voltage and good, stable power/ground before testing communication
  • Scan vehicle and record all stored/current codes and freeze frame data
  • Visually inspect DLC, TCU connectors and wiring for corrosion, bent pins or damage
  • Verify relevant fuses and ignition-switched power circuits
  • Check for other network/module communication DTCs that may indicate broader bus issues
  • Use a known-good scan tool or adapter to rule out tool incompatibility

Signal parameters

  • K-line idle state: should present pull-up behavior and show recognisable idle voltage with ignition ON (varies by vehicle)
  • When a diagnostic session is requested, K-line should show serial communication pulses (use scope or serial monitor)
  • Open circuit: no pulses and no voltage change when communicating
  • Short to ground: voltage pulled low or stuck low, preventing communication
  • Short to battery: line held high, no modulation during communication attempts

Diagnostic algorithm

  1. Retrieve and record all DTCs from all modules. Note if other communication U-codes are present.
  2. Verify battery voltage and inspect fuses related to TCU and diagnostic circuits; replace if blown.
  3. Visually inspect the DLC and TCU connectors for corrosion, bent pins, moisture or damaged insulation. Repair as needed.
  4. With ignition ON (engine off), measure voltage at the K-line pin at the DLC and at the TCU connector. Compare behavior while initiating communication with a scan tool.
  5. Check continuity of the K-line between the DLC and TCU (ignition OFF). Repair any open or high-resistance wiring.
  6. Check for shorts: measure resistance from K-line to ground and to battery (ignition OFF) to detect shorts to ground or power.
  7. If available, use an oscilloscope to observe waveform on K-line while attempting communication; look for proper serial pulses vs. noise/flatline.
  8. Disconnect non-essential modules or aftermarket devices that share wiring or grounding to identify interference sources.
  9. If wiring and connectors test good but problem persists, consider substituting a known-good TCU (when available) or have TCU bench-tested/repaired by a qualified specialist.
  10. After repair, clear codes and verify stable communication and proper transmission operation on road test.

Likely causes

  • Damaged or disconnected K-line connector at TCU
  • Corroded pins at DLC preventing signal reach
  • Broken wire or short to ground on K-line
  • Failed TCU communication driver

Fault status

⚠️ Status
TCU K-line communication fault detected: the transmission control unit is not responding or the K-line signal is missing/distorted. This indicates an issue with the K-line wiring/connector, power/ground, the TCU communication circuit, or external interference.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1.0-3.0 hours

Similar codes

U0100 U0073 U0121 P0603 P0700
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+100 karma for a short comment :)
Keep it short and practical. Up to 500 characters.
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Code

P1745

LINCOLN P — Powertrain

Transmission System Problems

Brand: LINCOLN
Type: P — Powertrain
Views: UK: 30 EN: 49 RU: 31
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Open or short in K-line wiring between diagnostic connector and TCU
  • Corroded, loose or damaged connector pins at TCU or DLC (data link connector)
  • Blown fuse or poor ignition/switched power affecting communication circuits
  • Faulty TCU (internal communication circuitry)
  • Interference from aftermarket electronics or improper grounding
  • Faulty diagnostic tool or improper connection

Symptoms

  • Unable to read or clear transmission codes with a scan tool
  • Transmission may default to limp/backup mode or shift irregularly
  • MIL (check engine light) or transmission warning lamp may be illuminated
  • Intermittent or no response when attempting TCU diagnostics
  • Other module communication errors present on scan tool

What to check

  • Verify battery voltage and good, stable power/ground before testing communication
  • Scan vehicle and record all stored/current codes and freeze frame data
  • Visually inspect DLC, TCU connectors and wiring for corrosion, bent pins or damage
  • Verify relevant fuses and ignition-switched power circuits
  • Check for other network/module communication DTCs that may indicate broader bus issues
  • Use a known-good scan tool or adapter to rule out tool incompatibility

Signal parameters

  • K-line idle state: should present pull-up behavior and show recognisable idle voltage with ignition ON (varies by vehicle)
  • When a diagnostic session is requested, K-line should show serial communication pulses (use scope or serial monitor)
  • Open circuit: no pulses and no voltage change when communicating
  • Short to ground: voltage pulled low or stuck low, preventing communication
  • Short to battery: line held high, no modulation during communication attempts

Diagnostic algorithm

  1. Retrieve and record all DTCs from all modules. Note if other communication U-codes are present.
  2. Verify battery voltage and inspect fuses related to TCU and diagnostic circuits; replace if blown.
  3. Visually inspect the DLC and TCU connectors for corrosion, bent pins, moisture or damaged insulation. Repair as needed.
  4. With ignition ON (engine off), measure voltage at the K-line pin at the DLC and at the TCU connector. Compare behavior while initiating communication with a scan tool.
  5. Check continuity of the K-line between the DLC and TCU (ignition OFF). Repair any open or high-resistance wiring.
  6. Check for shorts: measure resistance from K-line to ground and to battery (ignition OFF) to detect shorts to ground or power.
  7. If available, use an oscilloscope to observe waveform on K-line while attempting communication; look for proper serial pulses vs. noise/flatline.
  8. Disconnect non-essential modules or aftermarket devices that share wiring or grounding to identify interference sources.
  9. If wiring and connectors test good but problem persists, consider substituting a known-good TCU (when available) or have TCU bench-tested/repaired by a qualified specialist.
  10. After repair, clear codes and verify stable communication and proper transmission operation on road test.

Likely causes

  • Damaged or disconnected K-line connector at TCU
  • Corroded pins at DLC preventing signal reach
  • Broken wire or short to ground on K-line
  • Failed TCU communication driver

Fault status

⚠️ Status
TCU K-line communication fault detected: the transmission control unit is not responding or the K-line signal is missing/distorted. This indicates an issue with the K-line wiring/connector, power/ground, the TCU communication circuit, or external interference.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1.0-3.0 hours

Similar codes

U0100 U0073 U0121 P0603 P0700
166

Browse 166 LINCOLN manuals: repair procedures, diagnostics, wiring diagrams, component locations, service data and Labor Times by year, model and trim.

LINCOLN

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+100 karma for a short comment :)
Keep it short and practical. Up to 500 characters.
Send to email
Code

P1745

MAZDA P — Powertrain

Line Pressure Solenoid

Brand: MAZDA
Type: P — Powertrain
Views: UK: 28 EN: 51 RU: 35
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Open or short in K-line wiring between diagnostic connector and TCU
  • Corroded, loose or damaged connector pins at TCU or DLC (data link connector)
  • Blown fuse or poor ignition/switched power affecting communication circuits
  • Faulty TCU (internal communication circuitry)
  • Interference from aftermarket electronics or improper grounding
  • Faulty diagnostic tool or improper connection

Symptoms

  • Unable to read or clear transmission codes with a scan tool
  • Transmission may default to limp/backup mode or shift irregularly
  • MIL (check engine light) or transmission warning lamp may be illuminated
  • Intermittent or no response when attempting TCU diagnostics
  • Other module communication errors present on scan tool

What to check

  • Verify battery voltage and good, stable power/ground before testing communication
  • Scan vehicle and record all stored/current codes and freeze frame data
  • Visually inspect DLC, TCU connectors and wiring for corrosion, bent pins or damage
  • Verify relevant fuses and ignition-switched power circuits
  • Check for other network/module communication DTCs that may indicate broader bus issues
  • Use a known-good scan tool or adapter to rule out tool incompatibility

Signal parameters

  • K-line idle state: should present pull-up behavior and show recognisable idle voltage with ignition ON (varies by vehicle)
  • When a diagnostic session is requested, K-line should show serial communication pulses (use scope or serial monitor)
  • Open circuit: no pulses and no voltage change when communicating
  • Short to ground: voltage pulled low or stuck low, preventing communication
  • Short to battery: line held high, no modulation during communication attempts

Diagnostic algorithm

  1. Retrieve and record all DTCs from all modules. Note if other communication U-codes are present.
  2. Verify battery voltage and inspect fuses related to TCU and diagnostic circuits; replace if blown.
  3. Visually inspect the DLC and TCU connectors for corrosion, bent pins, moisture or damaged insulation. Repair as needed.
  4. With ignition ON (engine off), measure voltage at the K-line pin at the DLC and at the TCU connector. Compare behavior while initiating communication with a scan tool.
  5. Check continuity of the K-line between the DLC and TCU (ignition OFF). Repair any open or high-resistance wiring.
  6. Check for shorts: measure resistance from K-line to ground and to battery (ignition OFF) to detect shorts to ground or power.
  7. If available, use an oscilloscope to observe waveform on K-line while attempting communication; look for proper serial pulses vs. noise/flatline.
  8. Disconnect non-essential modules or aftermarket devices that share wiring or grounding to identify interference sources.
  9. If wiring and connectors test good but problem persists, consider substituting a known-good TCU (when available) or have TCU bench-tested/repaired by a qualified specialist.
  10. After repair, clear codes and verify stable communication and proper transmission operation on road test.

Likely causes

  • Damaged or disconnected K-line connector at TCU
  • Corroded pins at DLC preventing signal reach
  • Broken wire or short to ground on K-line
  • Failed TCU communication driver

Fault status

⚠️ Status
TCU K-line communication fault detected: the transmission control unit is not responding or the K-line signal is missing/distorted. This indicates an issue with the K-line wiring/connector, power/ground, the TCU communication circuit, or external interference.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1.0-3.0 hours

Similar codes

U0100 U0073 U0121 P0603 P0700
Your experience will help others
+100 karma for a short comment :)
Keep it short and practical. Up to 500 characters.
Send to email
Code

P1745

MERCURY P — Powertrain

Transmission system problems

Brand: MERCURY
Type: P — Powertrain
Views: UK: 32 EN: 46 RU: 29
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Open or short in K-line wiring between diagnostic connector and TCU
  • Corroded, loose or damaged connector pins at TCU or DLC (data link connector)
  • Blown fuse or poor ignition/switched power affecting communication circuits
  • Faulty TCU (internal communication circuitry)
  • Interference from aftermarket electronics or improper grounding
  • Faulty diagnostic tool or improper connection

Symptoms

  • Unable to read or clear transmission codes with a scan tool
  • Transmission may default to limp/backup mode or shift irregularly
  • MIL (check engine light) or transmission warning lamp may be illuminated
  • Intermittent or no response when attempting TCU diagnostics
  • Other module communication errors present on scan tool

What to check

  • Verify battery voltage and good, stable power/ground before testing communication
  • Scan vehicle and record all stored/current codes and freeze frame data
  • Visually inspect DLC, TCU connectors and wiring for corrosion, bent pins or damage
  • Verify relevant fuses and ignition-switched power circuits
  • Check for other network/module communication DTCs that may indicate broader bus issues
  • Use a known-good scan tool or adapter to rule out tool incompatibility

Signal parameters

  • K-line idle state: should present pull-up behavior and show recognisable idle voltage with ignition ON (varies by vehicle)
  • When a diagnostic session is requested, K-line should show serial communication pulses (use scope or serial monitor)
  • Open circuit: no pulses and no voltage change when communicating
  • Short to ground: voltage pulled low or stuck low, preventing communication
  • Short to battery: line held high, no modulation during communication attempts

Diagnostic algorithm

  1. Retrieve and record all DTCs from all modules. Note if other communication U-codes are present.
  2. Verify battery voltage and inspect fuses related to TCU and diagnostic circuits; replace if blown.
  3. Visually inspect the DLC and TCU connectors for corrosion, bent pins, moisture or damaged insulation. Repair as needed.
  4. With ignition ON (engine off), measure voltage at the K-line pin at the DLC and at the TCU connector. Compare behavior while initiating communication with a scan tool.
  5. Check continuity of the K-line between the DLC and TCU (ignition OFF). Repair any open or high-resistance wiring.
  6. Check for shorts: measure resistance from K-line to ground and to battery (ignition OFF) to detect shorts to ground or power.
  7. If available, use an oscilloscope to observe waveform on K-line while attempting communication; look for proper serial pulses vs. noise/flatline.
  8. Disconnect non-essential modules or aftermarket devices that share wiring or grounding to identify interference sources.
  9. If wiring and connectors test good but problem persists, consider substituting a known-good TCU (when available) or have TCU bench-tested/repaired by a qualified specialist.
  10. After repair, clear codes and verify stable communication and proper transmission operation on road test.

Likely causes

  • Damaged or disconnected K-line connector at TCU
  • Corroded pins at DLC preventing signal reach
  • Broken wire or short to ground on K-line
  • Failed TCU communication driver

Fault status

⚠️ Status
TCU K-line communication fault detected: the transmission control unit is not responding or the K-line signal is missing/distorted. This indicates an issue with the K-line wiring/connector, power/ground, the TCU communication circuit, or external interference.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1.0-3.0 hours

Similar codes

U0100 U0073 U0121 P0603 P0700
296

Browse 296 MERCURY manuals: repair procedures, diagnostics, wiring diagrams, component locations, service data and Labor Times by year, model and trim.

MERCURY

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+100 karma for a short comment :)
Keep it short and practical. Up to 500 characters.
Send to email
Code

P1745

MITSUBISHI P — Powertrain

CVT-ABS communication line open

Brand: MITSUBISHI
Type: P — Powertrain
Views: UK: 22 EN: 36 RU: 26
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Open or short in K-line wiring between diagnostic connector and TCU
  • Corroded, loose or damaged connector pins at TCU or DLC (data link connector)
  • Blown fuse or poor ignition/switched power affecting communication circuits
  • Faulty TCU (internal communication circuitry)
  • Interference from aftermarket electronics or improper grounding
  • Faulty diagnostic tool or improper connection

Symptoms

  • Unable to read or clear transmission codes with a scan tool
  • Transmission may default to limp/backup mode or shift irregularly
  • MIL (check engine light) or transmission warning lamp may be illuminated
  • Intermittent or no response when attempting TCU diagnostics
  • Other module communication errors present on scan tool

What to check

  • Verify battery voltage and good, stable power/ground before testing communication
  • Scan vehicle and record all stored/current codes and freeze frame data
  • Visually inspect DLC, TCU connectors and wiring for corrosion, bent pins or damage
  • Verify relevant fuses and ignition-switched power circuits
  • Check for other network/module communication DTCs that may indicate broader bus issues
  • Use a known-good scan tool or adapter to rule out tool incompatibility

Signal parameters

  • K-line idle state: should present pull-up behavior and show recognisable idle voltage with ignition ON (varies by vehicle)
  • When a diagnostic session is requested, K-line should show serial communication pulses (use scope or serial monitor)
  • Open circuit: no pulses and no voltage change when communicating
  • Short to ground: voltage pulled low or stuck low, preventing communication
  • Short to battery: line held high, no modulation during communication attempts

Diagnostic algorithm

  1. Retrieve and record all DTCs from all modules. Note if other communication U-codes are present.
  2. Verify battery voltage and inspect fuses related to TCU and diagnostic circuits; replace if blown.
  3. Visually inspect the DLC and TCU connectors for corrosion, bent pins, moisture or damaged insulation. Repair as needed.
  4. With ignition ON (engine off), measure voltage at the K-line pin at the DLC and at the TCU connector. Compare behavior while initiating communication with a scan tool.
  5. Check continuity of the K-line between the DLC and TCU (ignition OFF). Repair any open or high-resistance wiring.
  6. Check for shorts: measure resistance from K-line to ground and to battery (ignition OFF) to detect shorts to ground or power.
  7. If available, use an oscilloscope to observe waveform on K-line while attempting communication; look for proper serial pulses vs. noise/flatline.
  8. Disconnect non-essential modules or aftermarket devices that share wiring or grounding to identify interference sources.
  9. If wiring and connectors test good but problem persists, consider substituting a known-good TCU (when available) or have TCU bench-tested/repaired by a qualified specialist.
  10. After repair, clear codes and verify stable communication and proper transmission operation on road test.

Likely causes

  • Damaged or disconnected K-line connector at TCU
  • Corroded pins at DLC preventing signal reach
  • Broken wire or short to ground on K-line
  • Failed TCU communication driver

Fault status

⚠️ Status
TCU K-line communication fault detected: the transmission control unit is not responding or the K-line signal is missing/distorted. This indicates an issue with the K-line wiring/connector, power/ground, the TCU communication circuit, or external interference.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1.0-3.0 hours

Similar codes

U0100 U0073 U0121 P0603 P0700
406

Browse 406 MITSUBISHI manuals: repair procedures, diagnostics, wiring diagrams, component locations, service data and Labor Times by year, model and trim.

MITSUBISHI

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+100 karma for a short comment :)
Keep it short and practical. Up to 500 characters.
Send to email
Code

P1745

Other P — Powertrain

Line Pressure Solenoid System

Brand: Other
Type: P — Powertrain
Views: UK: 28 EN: 44 RU: 33
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Open or short in K-line wiring between diagnostic connector and TCU
  • Corroded, loose or damaged connector pins at TCU or DLC (data link connector)
  • Blown fuse or poor ignition/switched power affecting communication circuits
  • Faulty TCU (internal communication circuitry)
  • Interference from aftermarket electronics or improper grounding
  • Faulty diagnostic tool or improper connection

Symptoms

  • Unable to read or clear transmission codes with a scan tool
  • Transmission may default to limp/backup mode or shift irregularly
  • MIL (check engine light) or transmission warning lamp may be illuminated
  • Intermittent or no response when attempting TCU diagnostics
  • Other module communication errors present on scan tool

What to check

  • Verify battery voltage and good, stable power/ground before testing communication
  • Scan vehicle and record all stored/current codes and freeze frame data
  • Visually inspect DLC, TCU connectors and wiring for corrosion, bent pins or damage
  • Verify relevant fuses and ignition-switched power circuits
  • Check for other network/module communication DTCs that may indicate broader bus issues
  • Use a known-good scan tool or adapter to rule out tool incompatibility

Signal parameters

  • K-line idle state: should present pull-up behavior and show recognisable idle voltage with ignition ON (varies by vehicle)
  • When a diagnostic session is requested, K-line should show serial communication pulses (use scope or serial monitor)
  • Open circuit: no pulses and no voltage change when communicating
  • Short to ground: voltage pulled low or stuck low, preventing communication
  • Short to battery: line held high, no modulation during communication attempts

Diagnostic algorithm

  1. Retrieve and record all DTCs from all modules. Note if other communication U-codes are present.
  2. Verify battery voltage and inspect fuses related to TCU and diagnostic circuits; replace if blown.
  3. Visually inspect the DLC and TCU connectors for corrosion, bent pins, moisture or damaged insulation. Repair as needed.
  4. With ignition ON (engine off), measure voltage at the K-line pin at the DLC and at the TCU connector. Compare behavior while initiating communication with a scan tool.
  5. Check continuity of the K-line between the DLC and TCU (ignition OFF). Repair any open or high-resistance wiring.
  6. Check for shorts: measure resistance from K-line to ground and to battery (ignition OFF) to detect shorts to ground or power.
  7. If available, use an oscilloscope to observe waveform on K-line while attempting communication; look for proper serial pulses vs. noise/flatline.
  8. Disconnect non-essential modules or aftermarket devices that share wiring or grounding to identify interference sources.
  9. If wiring and connectors test good but problem persists, consider substituting a known-good TCU (when available) or have TCU bench-tested/repaired by a qualified specialist.
  10. After repair, clear codes and verify stable communication and proper transmission operation on road test.

Likely causes

  • Damaged or disconnected K-line connector at TCU
  • Corroded pins at DLC preventing signal reach
  • Broken wire or short to ground on K-line
  • Failed TCU communication driver

Fault status

⚠️ Status
TCU K-line communication fault detected: the transmission control unit is not responding or the K-line signal is missing/distorted. This indicates an issue with the K-line wiring/connector, power/ground, the TCU communication circuit, or external interference.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1.0-3.0 hours

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Code

P1745

RAM P — Powertrain

Transmission Line Pressure Too High for Too Long

Brand: RAM
Type: P — Powertrain
Views: UK: 19 EN: 31 RU: 21
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Open or short in K-line wiring between diagnostic connector and TCU
  • Corroded, loose or damaged connector pins at TCU or DLC (data link connector)
  • Blown fuse or poor ignition/switched power affecting communication circuits
  • Faulty TCU (internal communication circuitry)
  • Interference from aftermarket electronics or improper grounding
  • Faulty diagnostic tool or improper connection

Symptoms

  • Unable to read or clear transmission codes with a scan tool
  • Transmission may default to limp/backup mode or shift irregularly
  • MIL (check engine light) or transmission warning lamp may be illuminated
  • Intermittent or no response when attempting TCU diagnostics
  • Other module communication errors present on scan tool

What to check

  • Verify battery voltage and good, stable power/ground before testing communication
  • Scan vehicle and record all stored/current codes and freeze frame data
  • Visually inspect DLC, TCU connectors and wiring for corrosion, bent pins or damage
  • Verify relevant fuses and ignition-switched power circuits
  • Check for other network/module communication DTCs that may indicate broader bus issues
  • Use a known-good scan tool or adapter to rule out tool incompatibility

Signal parameters

  • K-line idle state: should present pull-up behavior and show recognisable idle voltage with ignition ON (varies by vehicle)
  • When a diagnostic session is requested, K-line should show serial communication pulses (use scope or serial monitor)
  • Open circuit: no pulses and no voltage change when communicating
  • Short to ground: voltage pulled low or stuck low, preventing communication
  • Short to battery: line held high, no modulation during communication attempts

Diagnostic algorithm

  1. Retrieve and record all DTCs from all modules. Note if other communication U-codes are present.
  2. Verify battery voltage and inspect fuses related to TCU and diagnostic circuits; replace if blown.
  3. Visually inspect the DLC and TCU connectors for corrosion, bent pins, moisture or damaged insulation. Repair as needed.
  4. With ignition ON (engine off), measure voltage at the K-line pin at the DLC and at the TCU connector. Compare behavior while initiating communication with a scan tool.
  5. Check continuity of the K-line between the DLC and TCU (ignition OFF). Repair any open or high-resistance wiring.
  6. Check for shorts: measure resistance from K-line to ground and to battery (ignition OFF) to detect shorts to ground or power.
  7. If available, use an oscilloscope to observe waveform on K-line while attempting communication; look for proper serial pulses vs. noise/flatline.
  8. Disconnect non-essential modules or aftermarket devices that share wiring or grounding to identify interference sources.
  9. If wiring and connectors test good but problem persists, consider substituting a known-good TCU (when available) or have TCU bench-tested/repaired by a qualified specialist.
  10. After repair, clear codes and verify stable communication and proper transmission operation on road test.

Likely causes

  • Damaged or disconnected K-line connector at TCU
  • Corroded pins at DLC preventing signal reach
  • Broken wire or short to ground on K-line
  • Failed TCU communication driver

Fault status

⚠️ Status
TCU K-line communication fault detected: the transmission control unit is not responding or the K-line signal is missing/distorted. This indicates an issue with the K-line wiring/connector, power/ground, the TCU communication circuit, or external interference.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1.0-3.0 hours

Similar codes

U0100 U0073 U0121 P0603 P0700
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+100 karma for a short comment :)
Keep it short and practical. Up to 500 characters.
Send to email
Code

P1745

VOLKSWAGEN P — Powertrain

Transmission Control Unit Relay Short To B+

Brand: VOLKSWAGEN
Type: P — Powertrain
Views: UK: 27 EN: 47 RU: 32
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Open or short in K-line wiring between diagnostic connector and TCU
  • Corroded, loose or damaged connector pins at TCU or DLC (data link connector)
  • Blown fuse or poor ignition/switched power affecting communication circuits
  • Faulty TCU (internal communication circuitry)
  • Interference from aftermarket electronics or improper grounding
  • Faulty diagnostic tool or improper connection

Symptoms

  • Unable to read or clear transmission codes with a scan tool
  • Transmission may default to limp/backup mode or shift irregularly
  • MIL (check engine light) or transmission warning lamp may be illuminated
  • Intermittent or no response when attempting TCU diagnostics
  • Other module communication errors present on scan tool

What to check

  • Verify battery voltage and good, stable power/ground before testing communication
  • Scan vehicle and record all stored/current codes and freeze frame data
  • Visually inspect DLC, TCU connectors and wiring for corrosion, bent pins or damage
  • Verify relevant fuses and ignition-switched power circuits
  • Check for other network/module communication DTCs that may indicate broader bus issues
  • Use a known-good scan tool or adapter to rule out tool incompatibility

Signal parameters

  • K-line idle state: should present pull-up behavior and show recognisable idle voltage with ignition ON (varies by vehicle)
  • When a diagnostic session is requested, K-line should show serial communication pulses (use scope or serial monitor)
  • Open circuit: no pulses and no voltage change when communicating
  • Short to ground: voltage pulled low or stuck low, preventing communication
  • Short to battery: line held high, no modulation during communication attempts

Diagnostic algorithm

  1. Retrieve and record all DTCs from all modules. Note if other communication U-codes are present.
  2. Verify battery voltage and inspect fuses related to TCU and diagnostic circuits; replace if blown.
  3. Visually inspect the DLC and TCU connectors for corrosion, bent pins, moisture or damaged insulation. Repair as needed.
  4. With ignition ON (engine off), measure voltage at the K-line pin at the DLC and at the TCU connector. Compare behavior while initiating communication with a scan tool.
  5. Check continuity of the K-line between the DLC and TCU (ignition OFF). Repair any open or high-resistance wiring.
  6. Check for shorts: measure resistance from K-line to ground and to battery (ignition OFF) to detect shorts to ground or power.
  7. If available, use an oscilloscope to observe waveform on K-line while attempting communication; look for proper serial pulses vs. noise/flatline.
  8. Disconnect non-essential modules or aftermarket devices that share wiring or grounding to identify interference sources.
  9. If wiring and connectors test good but problem persists, consider substituting a known-good TCU (when available) or have TCU bench-tested/repaired by a qualified specialist.
  10. After repair, clear codes and verify stable communication and proper transmission operation on road test.

Likely causes

  • Damaged or disconnected K-line connector at TCU
  • Corroded pins at DLC preventing signal reach
  • Broken wire or short to ground on K-line
  • Failed TCU communication driver

Fault status

⚠️ Status
TCU K-line communication fault detected: the transmission control unit is not responding or the K-line signal is missing/distorted. This indicates an issue with the K-line wiring/connector, power/ground, the TCU communication circuit, or external interference.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1.0-3.0 hours

Similar codes

U0100 U0073 U0121 P0603 P0700
139

Browse 139 VOLKSWAGEN manuals: repair procedures, diagnostics, wiring diagrams, component locations, service data and Labor Times by year, model and trim.

VOLKSWAGEN

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