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Home / DTC / U0198 — Lost Communication With Telematic Control Module

U0198 — Lost Communication With Telematic Control Module

Detailed page for trouble code U0198.

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59brands
11,451generic
22,461specific
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Code

U0198

Generic U — Network/User

Lost Communication With Telematic Control Module

Brand: Generic
Type: U — Network/User
Views: UK: 25 EN: 74 RU: 61
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • TCM (Telematic/Telematics Control Module) internal failure
  • Power or ground fault to the TCM (blown fuse, bad relay, open/short)
  • Open, short or high resistance on CAN/vehicle data bus wiring or connectors
  • Corroded, loose or damaged TCM connector
  • Module put to sleep or disabled by software/configuration
  • Network message collisions or bus flooding (electrical noise)

Symptoms

  • Telematics features inoperative (remote start, vehicle health, SOS/911, remote unlock)
  • Telematics-related warning or message on cluster or infotainment
  • Manufacturer telematics app shows offline or vehicle unavailable
  • No response from TCM when queried with a scan tool
  • Intermittent loss of remote functions; may be permanent
  • Possible related faults logged in other modules

What to check

  • Read all network DTCs with a capable scan tool and capture freeze frame/occurrence data
  • Verify battery voltage with key ON/engine OFF and during cranking (should be ~12.0–14.5V)
  • Check fuses and relays supplying the TCM for continuity and correct operation
  • Confirm TCM appears on the network (module list) with OEM scan tool
  • Inspect TCM connector for corrosion, bent pins, or water intrusion; reseat connector
  • Measure CAN bus voltages at the TCM connector (see signal parameters)

Signal parameters

  • Battery voltage to TCM: typically ~11–14.5 V with key ON (vehicle-dependent)
  • CAN bus idle voltages: CAN_H ≈ 2.5 V, CAN_L ≈ 2.5 V (recessive) — note: with differential tools expect ~2.5 V each
  • CAN dominant state: CAN_H ≈ 3.5 V, CAN_L ≈ 1.5 V (typical values; verify vehicle spec)
  • Bus continuity: CAN_H to CAN_L differential should be ~60–120 ohms (two 120Ω terminators parallel ≈ 60Ω)
  • No communication: no diagnostic response frames from TCM address, or repeated RTR/NAK/timeouts on network

Diagnostic algorithm

  1. Connect a full-function OEM-capable scan tool and read all U-codes and module status. Note time/date and freeze frame.
  2. Verify vehicle battery voltage and health. If low, charge or support with a stable power source before continuing.
  3. Verify TCM power and ground circuits: check fuses/relays, measure supply and ground at the module connector with key ON and during cranking.
  4. Confirm whether the TCM appears on the network: use scan tool module list or present diagnostic request to the TCM address. Record response/no-response behavior.
  5. Inspect the TCM connector and harness for damage, corrosion, moisture, and secure retention. Repair any visual issues and reseat connector.
  6. Measure CAN_H and CAN_L at the TCM connector for idle voltage, differential, and continuity to other nodes; verify termination resistance (~60Ω).
  7. Perform a wiggle/strain test on harness and connectors while monitoring network communication for faults or dropouts.
  8. Scan other modules for related U-codes (bus-off, other lost-communication codes). If another module is bus-off, diagnose that module first.
  9. If wiring and other modules are good, try power-cycling the TCM (per manufacturer procedure) or perform a soft reset via scan tool if available.
  10. Verify software/calibration levels; if the TCM was recently replaced or updated, reflash/update per OEM instructions and re-run diagnostics.
  11. If module is confirmed non-responsive after verifying power, ground, and network wiring, replace the TCM and reconfigure/program as required by manufacturer.
  12. After repair, clear DTCs, exercise the network, and confirm telematics services and scan tool communication are restored. Monitor for recurrence.

Likely causes

  • Faulty or unpowered TCM (fuse/ignition supply or internal fault)
  • Open or shorted CAN wiring to the TCM connector
  • Poor connector contact or corrosion at the TCM
  • Network bus error from another module causing the TCM to be unreadable
  • Software/firmware mismatch after module replacement or update

Fault status

⚠️ Status
U0198 — Lost Communication With Telematic Control Module. The telematics module is not responding on the vehicle data bus or to diagnostic requests.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1.0-3.0 hours

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Code

U0198

HYUNDAI U — Network/User

Lost Communication With Telematic Control Module

Brand: HYUNDAI
Type: U — Network/User
Views: UK: 23 EN: 63 RU: 48
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • TCM (Telematic/Telematics Control Module) internal failure
  • Power or ground fault to the TCM (blown fuse, bad relay, open/short)
  • Open, short or high resistance on CAN/vehicle data bus wiring or connectors
  • Corroded, loose or damaged TCM connector
  • Module put to sleep or disabled by software/configuration
  • Network message collisions or bus flooding (electrical noise)

Symptoms

  • Telematics features inoperative (remote start, vehicle health, SOS/911, remote unlock)
  • Telematics-related warning or message on cluster or infotainment
  • Manufacturer telematics app shows offline or vehicle unavailable
  • No response from TCM when queried with a scan tool
  • Intermittent loss of remote functions; may be permanent
  • Possible related faults logged in other modules

What to check

  • Read all network DTCs with a capable scan tool and capture freeze frame/occurrence data
  • Verify battery voltage with key ON/engine OFF and during cranking (should be ~12.0–14.5V)
  • Check fuses and relays supplying the TCM for continuity and correct operation
  • Confirm TCM appears on the network (module list) with OEM scan tool
  • Inspect TCM connector for corrosion, bent pins, or water intrusion; reseat connector
  • Measure CAN bus voltages at the TCM connector (see signal parameters)

Signal parameters

  • Battery voltage to TCM: typically ~11–14.5 V with key ON (vehicle-dependent)
  • CAN bus idle voltages: CAN_H ≈ 2.5 V, CAN_L ≈ 2.5 V (recessive) — note: with differential tools expect ~2.5 V each
  • CAN dominant state: CAN_H ≈ 3.5 V, CAN_L ≈ 1.5 V (typical values; verify vehicle spec)
  • Bus continuity: CAN_H to CAN_L differential should be ~60–120 ohms (two 120Ω terminators parallel ≈ 60Ω)
  • No communication: no diagnostic response frames from TCM address, or repeated RTR/NAK/timeouts on network

Diagnostic algorithm

  1. Connect a full-function OEM-capable scan tool and read all U-codes and module status. Note time/date and freeze frame.
  2. Verify vehicle battery voltage and health. If low, charge or support with a stable power source before continuing.
  3. Verify TCM power and ground circuits: check fuses/relays, measure supply and ground at the module connector with key ON and during cranking.
  4. Confirm whether the TCM appears on the network: use scan tool module list or present diagnostic request to the TCM address. Record response/no-response behavior.
  5. Inspect the TCM connector and harness for damage, corrosion, moisture, and secure retention. Repair any visual issues and reseat connector.
  6. Measure CAN_H and CAN_L at the TCM connector for idle voltage, differential, and continuity to other nodes; verify termination resistance (~60Ω).
  7. Perform a wiggle/strain test on harness and connectors while monitoring network communication for faults or dropouts.
  8. Scan other modules for related U-codes (bus-off, other lost-communication codes). If another module is bus-off, diagnose that module first.
  9. If wiring and other modules are good, try power-cycling the TCM (per manufacturer procedure) or perform a soft reset via scan tool if available.
  10. Verify software/calibration levels; if the TCM was recently replaced or updated, reflash/update per OEM instructions and re-run diagnostics.
  11. If module is confirmed non-responsive after verifying power, ground, and network wiring, replace the TCM and reconfigure/program as required by manufacturer.
  12. After repair, clear DTCs, exercise the network, and confirm telematics services and scan tool communication are restored. Monitor for recurrence.

Likely causes

  • Faulty or unpowered TCM (fuse/ignition supply or internal fault)
  • Open or shorted CAN wiring to the TCM connector
  • Poor connector contact or corrosion at the TCM
  • Network bus error from another module causing the TCM to be unreadable
  • Software/firmware mismatch after module replacement or update

Fault status

⚠️ Status
U0198 — Lost Communication With Telematic Control Module. The telematics module is not responding on the vehicle data bus or to diagnostic requests.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1.0-3.0 hours

Similar codes

U0100 U0073 U0121 U0140 U0155 U0105
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

U0198

MERCEDES-BENZ U — Network/User

Lost Communication with Telematic Control Module

Brand: MERCEDES-BENZ
Type: U — Network/User
Views: UK: 19 EN: 55 RU: 53
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • TCM (Telematic/Telematics Control Module) internal failure
  • Power or ground fault to the TCM (blown fuse, bad relay, open/short)
  • Open, short or high resistance on CAN/vehicle data bus wiring or connectors
  • Corroded, loose or damaged TCM connector
  • Module put to sleep or disabled by software/configuration
  • Network message collisions or bus flooding (electrical noise)

Symptoms

  • Telematics features inoperative (remote start, vehicle health, SOS/911, remote unlock)
  • Telematics-related warning or message on cluster or infotainment
  • Manufacturer telematics app shows offline or vehicle unavailable
  • No response from TCM when queried with a scan tool
  • Intermittent loss of remote functions; may be permanent
  • Possible related faults logged in other modules

What to check

  • Read all network DTCs with a capable scan tool and capture freeze frame/occurrence data
  • Verify battery voltage with key ON/engine OFF and during cranking (should be ~12.0–14.5V)
  • Check fuses and relays supplying the TCM for continuity and correct operation
  • Confirm TCM appears on the network (module list) with OEM scan tool
  • Inspect TCM connector for corrosion, bent pins, or water intrusion; reseat connector
  • Measure CAN bus voltages at the TCM connector (see signal parameters)

Signal parameters

  • Battery voltage to TCM: typically ~11–14.5 V with key ON (vehicle-dependent)
  • CAN bus idle voltages: CAN_H ≈ 2.5 V, CAN_L ≈ 2.5 V (recessive) — note: with differential tools expect ~2.5 V each
  • CAN dominant state: CAN_H ≈ 3.5 V, CAN_L ≈ 1.5 V (typical values; verify vehicle spec)
  • Bus continuity: CAN_H to CAN_L differential should be ~60–120 ohms (two 120Ω terminators parallel ≈ 60Ω)
  • No communication: no diagnostic response frames from TCM address, or repeated RTR/NAK/timeouts on network

Diagnostic algorithm

  1. Connect a full-function OEM-capable scan tool and read all U-codes and module status. Note time/date and freeze frame.
  2. Verify vehicle battery voltage and health. If low, charge or support with a stable power source before continuing.
  3. Verify TCM power and ground circuits: check fuses/relays, measure supply and ground at the module connector with key ON and during cranking.
  4. Confirm whether the TCM appears on the network: use scan tool module list or present diagnostic request to the TCM address. Record response/no-response behavior.
  5. Inspect the TCM connector and harness for damage, corrosion, moisture, and secure retention. Repair any visual issues and reseat connector.
  6. Measure CAN_H and CAN_L at the TCM connector for idle voltage, differential, and continuity to other nodes; verify termination resistance (~60Ω).
  7. Perform a wiggle/strain test on harness and connectors while monitoring network communication for faults or dropouts.
  8. Scan other modules for related U-codes (bus-off, other lost-communication codes). If another module is bus-off, diagnose that module first.
  9. If wiring and other modules are good, try power-cycling the TCM (per manufacturer procedure) or perform a soft reset via scan tool if available.
  10. Verify software/calibration levels; if the TCM was recently replaced or updated, reflash/update per OEM instructions and re-run diagnostics.
  11. If module is confirmed non-responsive after verifying power, ground, and network wiring, replace the TCM and reconfigure/program as required by manufacturer.
  12. After repair, clear DTCs, exercise the network, and confirm telematics services and scan tool communication are restored. Monitor for recurrence.

Likely causes

  • Faulty or unpowered TCM (fuse/ignition supply or internal fault)
  • Open or shorted CAN wiring to the TCM connector
  • Poor connector contact or corrosion at the TCM
  • Network bus error from another module causing the TCM to be unreadable
  • Software/firmware mismatch after module replacement or update

Fault status

⚠️ Status
U0198 — Lost Communication With Telematic Control Module. The telematics module is not responding on the vehicle data bus or to diagnostic requests.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1.0-3.0 hours

Similar codes

U0100 U0073 U0121 U0140 U0155 U0105
493

Browse 493 MERCEDES-BENZ manuals: repair procedures, diagnostics, wiring diagrams, component locations, service data and Labor Times by year, model and trim.

MERCEDES-BENZ

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

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