Code
U1700
ALFA ROMEO
U — Network/User
CAN bus communication between engine control module and body computer
Views:
UK: 7
EN: 22
RU: 13
AI status
Completed
Completed
100%
Causes
- Open or short in CAN High or CAN Low wiring between ECM and BCM
- Poor ground or battery power to one or both modules
- Faulty ECM or BCM (internal failure)
- Missing or incorrect CAN termination resistors
- Corroded or loose connector pins at ECM/BCM or intermediate junctions
- Intermittent wiring harness damage (chafing, water intrusion)
Symptoms
- MIL (check engine light) or multiple network warning lamps
- Loss of certain body or powertrain functions (e.g., remote locking, instrument cluster messages)
- Intermittent no-start or crank/no-start conditions if critical messages blocked
- Erratic operation of systems shared across modules
- Stored communication-related DTCs and possibly related module faults
What to check
- Retrieve freeze-frame and module list with a factory-level or capable scan tool; note other U-codes and related P-codes
- Check battery voltage (stable, fully charged) and main fuses/relays for ECM and BCM
- Visually inspect ECM and BCM connectors, wiring harnesses, and any splice/junctions for corrosion, damage, or water ingress
- Measure CAN bus voltages (CAN_H and CAN_L) at ECM and BCM with key ON, engine OFF
- Measure bus resistance across CAN_H to CAN_L with power removed (expected ~60 Ω for two 120 Ω terminations in parallel)
- Perform wiggle test on harness/connectors while monitoring live CAN traffic for interruptions
Signal parameters
- Recessive idle voltages: CAN_H ≈ 2.5 V, CAN_L ≈ 2.5 V (typical)
- Dominant state: CAN_H ≈ 3.5 V, CAN_L ≈ 1.5 V (differential ≈ 2 V)
- Voltage tolerance: expect CAN_H ≈ 2.5–3.5 V and CAN_L ≈ 1.5–2.5 V depending on bus state
- Termination resistance (power off): approx. 60 Ω across CAN_H and CAN_L for a network with two 120 Ω terminators
- Common bus speeds: high-speed CAN typically 500 kbps (verify OEM spec for vehicle)
Diagnostic algorithm
- Confirm code and capture any additional U- and P-codes and freeze-frame data with a scan tool.
- Verify battery voltage and main power/ground integrity to ECM and BCM. Repair weak battery/grounds before further testing.
- Inspect physical wiring: follow CAN pair from ECM to BCM (and intermediate junctions). Look for chafing, pin corrosion, water traps, or damaged insulation.
- With ignition ON (engine off), measure CAN_H and CAN_L at the ECM and BCM connectors. Compare to signal parameter ranges. Note if one node shows strongly different voltages.
- With vehicle power off, measure resistance across CAN_H-to-CAN_L at multiple nodes; expect ~60 Ω. If much lower/ higher, suspect short/open or missing terminator.
- Using a capable scan tool, check for presence of ECM/BCM on the bus (module list). If a module is not responding, disconnect suspected faulty module and observe bus behavior (isolate to identify failing node).
- Perform a wiggle test on wiring/connectors while monitoring live CAN traffic for interruptions or error frames.
- If a specific connector or harness section is at fault, repair or replace wiring and connectors. Use OEM repair methods (solder/crimp, heat shrink) and protect against moisture.
- If wiring and power/grounds are good and one module is not communicating, consider reflashing or replacing the non-communicating module per OEM procedures.
- After repairs, clear codes, perform functional tests and a road test while monitoring the bus to confirm the fault does not return.
Likely causes
- Broken or shorted CAN-L / CAN-H conductors between ECM and BCM
- Bad ground at ECU/BCM or low battery voltage
- Open/incorrect termination (missing 120 Ω resistors or short to ground)
- Corroded connector at ECM/BCM or junction splice
- Faulty body computer module
Fault status
Status
Communication error on CAN bus between Engine Control Module and Body Computer; messages missing or corrupted. Check power/ground, wiring continuity, terminations, and module operation.
Repair difficulty: Medium
Diagnostic time: 1.5 - 3.0 hours
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Code
U1700
FIAT
U — Network/User
CAN bus communication between engine control module and body computer
Views:
UK: 6
EN: 19
RU: 10
AI status
Completed
Completed
100%
Causes
- Open or short in CAN High or CAN Low wiring between ECM and BCM
- Poor ground or battery power to one or both modules
- Faulty ECM or BCM (internal failure)
- Missing or incorrect CAN termination resistors
- Corroded or loose connector pins at ECM/BCM or intermediate junctions
- Intermittent wiring harness damage (chafing, water intrusion)
Symptoms
- MIL (check engine light) or multiple network warning lamps
- Loss of certain body or powertrain functions (e.g., remote locking, instrument cluster messages)
- Intermittent no-start or crank/no-start conditions if critical messages blocked
- Erratic operation of systems shared across modules
- Stored communication-related DTCs and possibly related module faults
What to check
- Retrieve freeze-frame and module list with a factory-level or capable scan tool; note other U-codes and related P-codes
- Check battery voltage (stable, fully charged) and main fuses/relays for ECM and BCM
- Visually inspect ECM and BCM connectors, wiring harnesses, and any splice/junctions for corrosion, damage, or water ingress
- Measure CAN bus voltages (CAN_H and CAN_L) at ECM and BCM with key ON, engine OFF
- Measure bus resistance across CAN_H to CAN_L with power removed (expected ~60 Ω for two 120 Ω terminations in parallel)
- Perform wiggle test on harness/connectors while monitoring live CAN traffic for interruptions
Signal parameters
- Recessive idle voltages: CAN_H ≈ 2.5 V, CAN_L ≈ 2.5 V (typical)
- Dominant state: CAN_H ≈ 3.5 V, CAN_L ≈ 1.5 V (differential ≈ 2 V)
- Voltage tolerance: expect CAN_H ≈ 2.5–3.5 V and CAN_L ≈ 1.5–2.5 V depending on bus state
- Termination resistance (power off): approx. 60 Ω across CAN_H and CAN_L for a network with two 120 Ω terminators
- Common bus speeds: high-speed CAN typically 500 kbps (verify OEM spec for vehicle)
Diagnostic algorithm
- Confirm code and capture any additional U- and P-codes and freeze-frame data with a scan tool.
- Verify battery voltage and main power/ground integrity to ECM and BCM. Repair weak battery/grounds before further testing.
- Inspect physical wiring: follow CAN pair from ECM to BCM (and intermediate junctions). Look for chafing, pin corrosion, water traps, or damaged insulation.
- With ignition ON (engine off), measure CAN_H and CAN_L at the ECM and BCM connectors. Compare to signal parameter ranges. Note if one node shows strongly different voltages.
- With vehicle power off, measure resistance across CAN_H-to-CAN_L at multiple nodes; expect ~60 Ω. If much lower/ higher, suspect short/open or missing terminator.
- Using a capable scan tool, check for presence of ECM/BCM on the bus (module list). If a module is not responding, disconnect suspected faulty module and observe bus behavior (isolate to identify failing node).
- Perform a wiggle test on wiring/connectors while monitoring live CAN traffic for interruptions or error frames.
- If a specific connector or harness section is at fault, repair or replace wiring and connectors. Use OEM repair methods (solder/crimp, heat shrink) and protect against moisture.
- If wiring and power/grounds are good and one module is not communicating, consider reflashing or replacing the non-communicating module per OEM procedures.
- After repairs, clear codes, perform functional tests and a road test while monitoring the bus to confirm the fault does not return.
Likely causes
- Broken or shorted CAN-L / CAN-H conductors between ECM and BCM
- Bad ground at ECU/BCM or low battery voltage
- Open/incorrect termination (missing 120 Ω resistors or short to ground)
- Corroded connector at ECM/BCM or junction splice
- Faulty body computer module
Fault status
Status
Communication error on CAN bus between Engine Control Module and Body Computer; messages missing or corrupted. Check power/ground, wiring continuity, terminations, and module operation.
Repair difficulty: Medium
Diagnostic time: 1.5 - 3.0 hours
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Code
U1700
Generic
U — Network/User
Control Module Communication - Bus Off
Views:
UK: 1
EN: 0
RU: 0
AI status
Completed
Completed
100%
Causes
- Open or short in CAN High or CAN Low wiring between ECM and BCM
- Poor ground or battery power to one or both modules
- Faulty ECM or BCM (internal failure)
- Missing or incorrect CAN termination resistors
- Corroded or loose connector pins at ECM/BCM or intermediate junctions
- Intermittent wiring harness damage (chafing, water intrusion)
Symptoms
- MIL (check engine light) or multiple network warning lamps
- Loss of certain body or powertrain functions (e.g., remote locking, instrument cluster messages)
- Intermittent no-start or crank/no-start conditions if critical messages blocked
- Erratic operation of systems shared across modules
- Stored communication-related DTCs and possibly related module faults
What to check
- Retrieve freeze-frame and module list with a factory-level or capable scan tool; note other U-codes and related P-codes
- Check battery voltage (stable, fully charged) and main fuses/relays for ECM and BCM
- Visually inspect ECM and BCM connectors, wiring harnesses, and any splice/junctions for corrosion, damage, or water ingress
- Measure CAN bus voltages (CAN_H and CAN_L) at ECM and BCM with key ON, engine OFF
- Measure bus resistance across CAN_H to CAN_L with power removed (expected ~60 Ω for two 120 Ω terminations in parallel)
- Perform wiggle test on harness/connectors while monitoring live CAN traffic for interruptions
Signal parameters
- Recessive idle voltages: CAN_H ≈ 2.5 V, CAN_L ≈ 2.5 V (typical)
- Dominant state: CAN_H ≈ 3.5 V, CAN_L ≈ 1.5 V (differential ≈ 2 V)
- Voltage tolerance: expect CAN_H ≈ 2.5–3.5 V and CAN_L ≈ 1.5–2.5 V depending on bus state
- Termination resistance (power off): approx. 60 Ω across CAN_H and CAN_L for a network with two 120 Ω terminators
- Common bus speeds: high-speed CAN typically 500 kbps (verify OEM spec for vehicle)
Diagnostic algorithm
- Confirm code and capture any additional U- and P-codes and freeze-frame data with a scan tool.
- Verify battery voltage and main power/ground integrity to ECM and BCM. Repair weak battery/grounds before further testing.
- Inspect physical wiring: follow CAN pair from ECM to BCM (and intermediate junctions). Look for chafing, pin corrosion, water traps, or damaged insulation.
- With ignition ON (engine off), measure CAN_H and CAN_L at the ECM and BCM connectors. Compare to signal parameter ranges. Note if one node shows strongly different voltages.
- With vehicle power off, measure resistance across CAN_H-to-CAN_L at multiple nodes; expect ~60 Ω. If much lower/ higher, suspect short/open or missing terminator.
- Using a capable scan tool, check for presence of ECM/BCM on the bus (module list). If a module is not responding, disconnect suspected faulty module and observe bus behavior (isolate to identify failing node).
- Perform a wiggle test on wiring/connectors while monitoring live CAN traffic for interruptions or error frames.
- If a specific connector or harness section is at fault, repair or replace wiring and connectors. Use OEM repair methods (solder/crimp, heat shrink) and protect against moisture.
- If wiring and power/grounds are good and one module is not communicating, consider reflashing or replacing the non-communicating module per OEM procedures.
- After repairs, clear codes, perform functional tests and a road test while monitoring the bus to confirm the fault does not return.
Likely causes
- Broken or shorted CAN-L / CAN-H conductors between ECM and BCM
- Bad ground at ECU/BCM or low battery voltage
- Open/incorrect termination (missing 120 Ω resistors or short to ground)
- Corroded connector at ECM/BCM or junction splice
- Faulty body computer module
Fault status
Status
Communication error on CAN bus between Engine Control Module and Body Computer; messages missing or corrupted. Check power/ground, wiring continuity, terminations, and module operation.
Repair difficulty: Medium
Diagnostic time: 1.5 - 3.0 hours
Workshop Manuals
Available brands with manuals
2
AUDI 11
6-speed manual gearbox 0B1, front-wheel drive — Workshop Manual (Edition 05.2014)
Workshop Manual199,00 UAH
Audi A3 (1997) – 1.6L 4-cylinder (2‑valve) Engine Mechanical Components Service Manual (AEH, AKL, APF) – Edition 07.2002
Workshop Manual199,00 UAH
AUDI A3 (2004) Workshop Manual — 2.0L FSI Turbo (4‑cyl, 4‑valve) Engine, Mechanics — Edition 03.2017
Workshop Manual199,00 UAH
Audi A3 2004 — Electrical System (Workshop Manual, Edition 02.2018)
Workshop Manual199,00 UAH
Audi A4 / A4 Cabriolet – 4.2 l V8 (5‑valve, timing chains) – Workshop Manual (Mechanics) – Edition 04.2007
Workshop Manual199,00 UAH
Audi A4 / A4 Cabriolet — Auxiliary Heater Workshop Manual (Edition 08.2004)
Workshop Manual199,00 UAH
Audi A4 / A4 Cabriolet (1.8T 4‑cyl turbo) — Motronic Injection & Ignition System Service Manual (Edition 01.2015)
Workshop Manual199,00 UAH
Audi A8 (2003) — Electrical System Workshop Manual (Edition 08.2014)
Workshop Manual199,00 UAH
Audi Q4 e-tron (Type F4) - Self-study Programme SSP 685
Workshop Manual199,00 UAH
Audi Q8 (2018) — Electrical System Workshop Manual (Edition 05.2019)
Workshop Manual199,00 UAH
Audi Servicing Manual — 7‑Speed Dual Clutch Transmission 0CJ / 0CL / 0CK / 0DN / 0DP / 0HL (Edition 05.2018)
Workshop Manual199,00 UAH
LAND ROVER 3
Land Rover Defender 300Tdi — Workshop Manual (1996 model year)
Workshop Manual199,00 UAH
Land Rover Defender Workshop Manual Supplement & Body Repair Manual (1999 & 2002 MY)
Workshop Manual199,00 UAH
Land Rover Range Rover — Electrical Library (LRL 0453ENG, 2002)
Workshop Manual199,00 UAH
Your experience will help others
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Was this AI description helpful?
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Send to email
Code
U1700
HYUNDAI
U — Network/User
DTCP Sink SW error.
Views:
UK: 11
EN: 38
RU: 16
AI status
Completed
Completed
100%
Causes
- Open or short in CAN High or CAN Low wiring between ECM and BCM
- Poor ground or battery power to one or both modules
- Faulty ECM or BCM (internal failure)
- Missing or incorrect CAN termination resistors
- Corroded or loose connector pins at ECM/BCM or intermediate junctions
- Intermittent wiring harness damage (chafing, water intrusion)
Symptoms
- MIL (check engine light) or multiple network warning lamps
- Loss of certain body or powertrain functions (e.g., remote locking, instrument cluster messages)
- Intermittent no-start or crank/no-start conditions if critical messages blocked
- Erratic operation of systems shared across modules
- Stored communication-related DTCs and possibly related module faults
What to check
- Retrieve freeze-frame and module list with a factory-level or capable scan tool; note other U-codes and related P-codes
- Check battery voltage (stable, fully charged) and main fuses/relays for ECM and BCM
- Visually inspect ECM and BCM connectors, wiring harnesses, and any splice/junctions for corrosion, damage, or water ingress
- Measure CAN bus voltages (CAN_H and CAN_L) at ECM and BCM with key ON, engine OFF
- Measure bus resistance across CAN_H to CAN_L with power removed (expected ~60 Ω for two 120 Ω terminations in parallel)
- Perform wiggle test on harness/connectors while monitoring live CAN traffic for interruptions
Signal parameters
- Recessive idle voltages: CAN_H ≈ 2.5 V, CAN_L ≈ 2.5 V (typical)
- Dominant state: CAN_H ≈ 3.5 V, CAN_L ≈ 1.5 V (differential ≈ 2 V)
- Voltage tolerance: expect CAN_H ≈ 2.5–3.5 V and CAN_L ≈ 1.5–2.5 V depending on bus state
- Termination resistance (power off): approx. 60 Ω across CAN_H and CAN_L for a network with two 120 Ω terminators
- Common bus speeds: high-speed CAN typically 500 kbps (verify OEM spec for vehicle)
Diagnostic algorithm
- Confirm code and capture any additional U- and P-codes and freeze-frame data with a scan tool.
- Verify battery voltage and main power/ground integrity to ECM and BCM. Repair weak battery/grounds before further testing.
- Inspect physical wiring: follow CAN pair from ECM to BCM (and intermediate junctions). Look for chafing, pin corrosion, water traps, or damaged insulation.
- With ignition ON (engine off), measure CAN_H and CAN_L at the ECM and BCM connectors. Compare to signal parameter ranges. Note if one node shows strongly different voltages.
- With vehicle power off, measure resistance across CAN_H-to-CAN_L at multiple nodes; expect ~60 Ω. If much lower/ higher, suspect short/open or missing terminator.
- Using a capable scan tool, check for presence of ECM/BCM on the bus (module list). If a module is not responding, disconnect suspected faulty module and observe bus behavior (isolate to identify failing node).
- Perform a wiggle test on wiring/connectors while monitoring live CAN traffic for interruptions or error frames.
- If a specific connector or harness section is at fault, repair or replace wiring and connectors. Use OEM repair methods (solder/crimp, heat shrink) and protect against moisture.
- If wiring and power/grounds are good and one module is not communicating, consider reflashing or replacing the non-communicating module per OEM procedures.
- After repairs, clear codes, perform functional tests and a road test while monitoring the bus to confirm the fault does not return.
Likely causes
- Broken or shorted CAN-L / CAN-H conductors between ECM and BCM
- Bad ground at ECU/BCM or low battery voltage
- Open/incorrect termination (missing 120 Ω resistors or short to ground)
- Corroded connector at ECM/BCM or junction splice
- Faulty body computer module
Fault status
Status
Communication error on CAN bus between Engine Control Module and Body Computer; messages missing or corrupted. Check power/ground, wiring continuity, terminations, and module operation.
Repair difficulty: Medium
Diagnostic time: 1.5 - 3.0 hours
Your experience will help others
+100 karma for a short comment :)
Was this AI description helpful?
Your feedback helps improve AI descriptions.
👍 Like
0
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0
Send to email