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Home / DTC / U0197 — Lost Communication With Telephone Control Module

U0197 — Lost Communication With Telephone Control Module

Detailed page for trouble code U0197.

34,405codes
59brands
11,914generic
22,491specific
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U0197

Generic U — Network/User

Lost Communication With Telephone Control Module

Brand: Generic
Type: U — Network/User
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Telephone control module failure
  • Loss of module power or ground (blown fuse, disconnected/failed power feed)
  • Damaged or disconnected wiring or connectors to the module
  • CAN/LIN bus wiring fault (open, short to ground/power, high resistance)
  • Network termination or bus short (low resistance or missing termination)
  • Battery low voltage or poor battery connections

Symptoms

  • Loss of hands-free phone, Bluetooth, or telematics services (SOS, concierge)
  • Telematics or phone menu/options disabled or not responding
  • Warning or communication error messages on the instrument cluster or infotainment screen
  • Other network-related features not functioning if the module shared the bus
  • Stored U0197 code and possibly other network communication DTCs

What to check

  • Scan vehicle for U0197 and any related U0xxx codes; record freeze frame and history data
  • Check battery voltage (key on and cranking) and battery connections
  • Verify fuses and relays powering the telephone control module
  • Visually inspect the module connectors and wiring for damage, corrosion, or water intrusion
  • Check for presence of the module in the scanner’s module list (does tool detect the module?)
  • Measure CAN bus voltages at the module connector (CAN_H, CAN_L) with key on, engine off

Signal parameters

  • CAN bus recessive voltages: CAN_H ≈ 2.5 V, CAN_L ≈ 2.5 V (idle)
  • CAN bus dominant voltages: CAN_H ≈ 3.5 V, CAN_L ≈ 1.5 V (during transmission) — verify with scope
  • Expected bus termination: total ≈ 60 Ω across CAN_H and CAN_L
  • Typical CAN data rate: 250 kb/s or 500 kb/s depending on vehicle (check OEM spec)
  • Module should respond to diagnostic request frames; absence indicates no communication

Diagnostic algorithm

  1. Retrieve and record all network communication DTCs and freeze frame data.
  2. Confirm battery voltage is within specification (≥12.4 V at rest); retest after charging if low.
  3. Inspect fuses and wiring for the telephone control module; replace any blown fuses and repair visible damage.
  4. With ignition on, confirm power and ground at the module connector (measure pin voltages).
  5. Check connector integrity: disconnect, inspect pins for corrosion/bent pins, then reconnect securely.
  6. Check CAN bus presence at the module: measure CAN_H and CAN_L with a multimeter and verify against expected idle voltages.
  7. Use an oscilloscope or CAN bus analyzer to view frames on the bus and confirm whether the telephone module transmits or receives frames. Look for bus errors or bus-off conditions.
  8. Measure termination resistance across CAN_H and CAN_L; repair missing or incorrect terminators.
  9. If wiring is suspect, perform continuity and short-to-power/ground tests from the module connector to the next nodes and to chassis ground.
  10. Isolate network segments if possible (disconnect nearby modules or harness branches) to identify a faulty device causing bus issues.
  11. If wiring and power/ground are good but no communication, verify software/firmware version and reflash or update the module per OEM procedures if available.
  12. If module fails to communicate after all checks and known-good network present, consider replacing the telephone control module and program it per manufacturer procedure.

Likely causes

  • Blown fuse or disconnected power/ground to the telephone control module
  • Damaged connector pins or corrosion at the module harness
  • Open or shorted CAN bus wiring near the telephone module
  • Telephone module hardware failure
  • Another module placed the network in bus-off or collision state

Fault status

⚠️ Status
Lost communication with the Telephone Control Module — no responses received from the telematics/phone module on the vehicle data bus.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1.5-3.5 hours
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Code

U0197

HYUNDAI U — Network/User

Lost Communication With Telephone Control Module

Brand: HYUNDAI
Type: U — Network/User
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Telephone control module failure
  • Loss of module power or ground (blown fuse, disconnected/failed power feed)
  • Damaged or disconnected wiring or connectors to the module
  • CAN/LIN bus wiring fault (open, short to ground/power, high resistance)
  • Network termination or bus short (low resistance or missing termination)
  • Battery low voltage or poor battery connections

Symptoms

  • Loss of hands-free phone, Bluetooth, or telematics services (SOS, concierge)
  • Telematics or phone menu/options disabled or not responding
  • Warning or communication error messages on the instrument cluster or infotainment screen
  • Other network-related features not functioning if the module shared the bus
  • Stored U0197 code and possibly other network communication DTCs

What to check

  • Scan vehicle for U0197 and any related U0xxx codes; record freeze frame and history data
  • Check battery voltage (key on and cranking) and battery connections
  • Verify fuses and relays powering the telephone control module
  • Visually inspect the module connectors and wiring for damage, corrosion, or water intrusion
  • Check for presence of the module in the scanner’s module list (does tool detect the module?)
  • Measure CAN bus voltages at the module connector (CAN_H, CAN_L) with key on, engine off

Signal parameters

  • CAN bus recessive voltages: CAN_H ≈ 2.5 V, CAN_L ≈ 2.5 V (idle)
  • CAN bus dominant voltages: CAN_H ≈ 3.5 V, CAN_L ≈ 1.5 V (during transmission) — verify with scope
  • Expected bus termination: total ≈ 60 Ω across CAN_H and CAN_L
  • Typical CAN data rate: 250 kb/s or 500 kb/s depending on vehicle (check OEM spec)
  • Module should respond to diagnostic request frames; absence indicates no communication

Diagnostic algorithm

  1. Retrieve and record all network communication DTCs and freeze frame data.
  2. Confirm battery voltage is within specification (≥12.4 V at rest); retest after charging if low.
  3. Inspect fuses and wiring for the telephone control module; replace any blown fuses and repair visible damage.
  4. With ignition on, confirm power and ground at the module connector (measure pin voltages).
  5. Check connector integrity: disconnect, inspect pins for corrosion/bent pins, then reconnect securely.
  6. Check CAN bus presence at the module: measure CAN_H and CAN_L with a multimeter and verify against expected idle voltages.
  7. Use an oscilloscope or CAN bus analyzer to view frames on the bus and confirm whether the telephone module transmits or receives frames. Look for bus errors or bus-off conditions.
  8. Measure termination resistance across CAN_H and CAN_L; repair missing or incorrect terminators.
  9. If wiring is suspect, perform continuity and short-to-power/ground tests from the module connector to the next nodes and to chassis ground.
  10. Isolate network segments if possible (disconnect nearby modules or harness branches) to identify a faulty device causing bus issues.
  11. If wiring and power/ground are good but no communication, verify software/firmware version and reflash or update the module per OEM procedures if available.
  12. If module fails to communicate after all checks and known-good network present, consider replacing the telephone control module and program it per manufacturer procedure.

Likely causes

  • Blown fuse or disconnected power/ground to the telephone control module
  • Damaged connector pins or corrosion at the module harness
  • Open or shorted CAN bus wiring near the telephone module
  • Telephone module hardware failure
  • Another module placed the network in bus-off or collision state

Fault status

⚠️ Status
Lost communication with the Telephone Control Module — no responses received from the telematics/phone module on the vehicle data bus.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1.5-3.5 hours
371

Browse 371 HYUNDAI manuals: repair procedures, diagnostics, wiring diagrams, component locations, service data and Labor Times by year, model and trim.

HYUNDAI

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Code

U0197

LAND ROVER U — Network/User

Lost communication with the phone control module

Brand: LAND ROVER
Type: U — Network/User
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Telephone control module failure
  • Loss of module power or ground (blown fuse, disconnected/failed power feed)
  • Damaged or disconnected wiring or connectors to the module
  • CAN/LIN bus wiring fault (open, short to ground/power, high resistance)
  • Network termination or bus short (low resistance or missing termination)
  • Battery low voltage or poor battery connections

Symptoms

  • Loss of hands-free phone, Bluetooth, or telematics services (SOS, concierge)
  • Telematics or phone menu/options disabled or not responding
  • Warning or communication error messages on the instrument cluster or infotainment screen
  • Other network-related features not functioning if the module shared the bus
  • Stored U0197 code and possibly other network communication DTCs

What to check

  • Scan vehicle for U0197 and any related U0xxx codes; record freeze frame and history data
  • Check battery voltage (key on and cranking) and battery connections
  • Verify fuses and relays powering the telephone control module
  • Visually inspect the module connectors and wiring for damage, corrosion, or water intrusion
  • Check for presence of the module in the scanner’s module list (does tool detect the module?)
  • Measure CAN bus voltages at the module connector (CAN_H, CAN_L) with key on, engine off

Signal parameters

  • CAN bus recessive voltages: CAN_H ≈ 2.5 V, CAN_L ≈ 2.5 V (idle)
  • CAN bus dominant voltages: CAN_H ≈ 3.5 V, CAN_L ≈ 1.5 V (during transmission) — verify with scope
  • Expected bus termination: total ≈ 60 Ω across CAN_H and CAN_L
  • Typical CAN data rate: 250 kb/s or 500 kb/s depending on vehicle (check OEM spec)
  • Module should respond to diagnostic request frames; absence indicates no communication

Diagnostic algorithm

  1. Retrieve and record all network communication DTCs and freeze frame data.
  2. Confirm battery voltage is within specification (≥12.4 V at rest); retest after charging if low.
  3. Inspect fuses and wiring for the telephone control module; replace any blown fuses and repair visible damage.
  4. With ignition on, confirm power and ground at the module connector (measure pin voltages).
  5. Check connector integrity: disconnect, inspect pins for corrosion/bent pins, then reconnect securely.
  6. Check CAN bus presence at the module: measure CAN_H and CAN_L with a multimeter and verify against expected idle voltages.
  7. Use an oscilloscope or CAN bus analyzer to view frames on the bus and confirm whether the telephone module transmits or receives frames. Look for bus errors or bus-off conditions.
  8. Measure termination resistance across CAN_H and CAN_L; repair missing or incorrect terminators.
  9. If wiring is suspect, perform continuity and short-to-power/ground tests from the module connector to the next nodes and to chassis ground.
  10. Isolate network segments if possible (disconnect nearby modules or harness branches) to identify a faulty device causing bus issues.
  11. If wiring and power/ground are good but no communication, verify software/firmware version and reflash or update the module per OEM procedures if available.
  12. If module fails to communicate after all checks and known-good network present, consider replacing the telephone control module and program it per manufacturer procedure.

Likely causes

  • Blown fuse or disconnected power/ground to the telephone control module
  • Damaged connector pins or corrosion at the module harness
  • Open or shorted CAN bus wiring near the telephone module
  • Telephone module hardware failure
  • Another module placed the network in bus-off or collision state

Fault status

⚠️ Status
Lost communication with the Telephone Control Module — no responses received from the telematics/phone module on the vehicle data bus.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1.5-3.5 hours
320

Browse 320 LAND ROVER manuals: repair procedures, diagnostics, wiring diagrams, component locations, service data and Labor Times by year, model and trim.

LAND ROVER

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Code

U0197

MERCEDES-BENZ U — Network/User

Lost Communication with Telephone Control Module

Brand: MERCEDES-BENZ
Type: U — Network/User
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Telephone control module failure
  • Loss of module power or ground (blown fuse, disconnected/failed power feed)
  • Damaged or disconnected wiring or connectors to the module
  • CAN/LIN bus wiring fault (open, short to ground/power, high resistance)
  • Network termination or bus short (low resistance or missing termination)
  • Battery low voltage or poor battery connections

Symptoms

  • Loss of hands-free phone, Bluetooth, or telematics services (SOS, concierge)
  • Telematics or phone menu/options disabled or not responding
  • Warning or communication error messages on the instrument cluster or infotainment screen
  • Other network-related features not functioning if the module shared the bus
  • Stored U0197 code and possibly other network communication DTCs

What to check

  • Scan vehicle for U0197 and any related U0xxx codes; record freeze frame and history data
  • Check battery voltage (key on and cranking) and battery connections
  • Verify fuses and relays powering the telephone control module
  • Visually inspect the module connectors and wiring for damage, corrosion, or water intrusion
  • Check for presence of the module in the scanner’s module list (does tool detect the module?)
  • Measure CAN bus voltages at the module connector (CAN_H, CAN_L) with key on, engine off

Signal parameters

  • CAN bus recessive voltages: CAN_H ≈ 2.5 V, CAN_L ≈ 2.5 V (idle)
  • CAN bus dominant voltages: CAN_H ≈ 3.5 V, CAN_L ≈ 1.5 V (during transmission) — verify with scope
  • Expected bus termination: total ≈ 60 Ω across CAN_H and CAN_L
  • Typical CAN data rate: 250 kb/s or 500 kb/s depending on vehicle (check OEM spec)
  • Module should respond to diagnostic request frames; absence indicates no communication

Diagnostic algorithm

  1. Retrieve and record all network communication DTCs and freeze frame data.
  2. Confirm battery voltage is within specification (≥12.4 V at rest); retest after charging if low.
  3. Inspect fuses and wiring for the telephone control module; replace any blown fuses and repair visible damage.
  4. With ignition on, confirm power and ground at the module connector (measure pin voltages).
  5. Check connector integrity: disconnect, inspect pins for corrosion/bent pins, then reconnect securely.
  6. Check CAN bus presence at the module: measure CAN_H and CAN_L with a multimeter and verify against expected idle voltages.
  7. Use an oscilloscope or CAN bus analyzer to view frames on the bus and confirm whether the telephone module transmits or receives frames. Look for bus errors or bus-off conditions.
  8. Measure termination resistance across CAN_H and CAN_L; repair missing or incorrect terminators.
  9. If wiring is suspect, perform continuity and short-to-power/ground tests from the module connector to the next nodes and to chassis ground.
  10. Isolate network segments if possible (disconnect nearby modules or harness branches) to identify a faulty device causing bus issues.
  11. If wiring and power/ground are good but no communication, verify software/firmware version and reflash or update the module per OEM procedures if available.
  12. If module fails to communicate after all checks and known-good network present, consider replacing the telephone control module and program it per manufacturer procedure.

Likely causes

  • Blown fuse or disconnected power/ground to the telephone control module
  • Damaged connector pins or corrosion at the module harness
  • Open or shorted CAN bus wiring near the telephone module
  • Telephone module hardware failure
  • Another module placed the network in bus-off or collision state

Fault status

⚠️ Status
Lost communication with the Telephone Control Module — no responses received from the telematics/phone module on the vehicle data bus.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1.5-3.5 hours
856

Browse 856 MERCEDES-BENZ manuals: repair procedures, diagnostics, wiring diagrams, component locations, service data and Labor Times by year, model and trim.

MERCEDES-BENZ

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Keep it short and practical. Up to 500 characters.
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