B10A7

Code

Generic B — Body

Telematics Control Module Communication Fault

Brand: Generic

Type: B — Body

Views: UK: 13 EN: 15 RU: 10

AI status

Completed

ready

Completed 100%

Page language: EN

Causes

Open or shorted CAN/LIN wiring between telematics module and network
Poor or corroded connector pins at the telematics module or gateway
Loss of module supply voltage or ground
Failed or unresponsive telematics control module (hardware or firmware)
Missing/incorrect network termination or bus wiring fault
Intermittent power/battery issues or low battery voltage

Symptoms

Telematics services unavailable (remote start, SOS, vehicle locator, diagnostics)
Telematics warning or message displayed on cluster or infotainment screen
Other modules report lost communication or set related U-codes
No response from telematics module when queried with a scan tool
Intermittent network faults or repeated communication-related DTCs
Possible rapid battery drain if module stuck awake

What to check

Use OEM scan tool to read DTCs and freeze frame; note any related U- or B-codes
Attempt to communicate with the telematics control module via diagnostic tool (identify, read parameters)
Inspect connector at the telematics module for corrosion, bent pins, water intrusion or damaged locking tangs
Check fuses and back-up power for the telematics module
Measure module supply voltage with key ON and with vehicle asleep (expected ~11–14.5 V when awake)
Measure module ground resistance to chassis (

Signal parameters

TCM supply voltage (Key ON, Awake): ~11.0–14.5 V
Module ground: low resistance to chassis,
CAN bus idle voltages: CAN_H ≈ 2.5 V, CAN_L ≈ 2.5 V (recessive state)
CAN dominant state: CAN_H ≈ 3.5 V, CAN_L ≈ 1.5 V during transmission
CAN differential termination: ~60 Ω measured between CAN_H and CAN_L at the module (two 120 Ω in parallel typical)
LIN bus idle: near battery voltage when awake (single-wire bus)

Diagnostic algorithm

Retrieve and record all DTCs and freeze-frame data with an OEM-capable scan tool; note time and module IDs.
Attempt direct communication with the telematics module; if tool cannot communicate, confirm whether gateway or network bus accepts commands to other nodes.
Visually inspect the telematics module connector, harness and antenna feed for physical damage, corrosion or evidence of water intrusion; repair as needed.
Verify fuses and power feeds to the module; measure supply voltage with key ON and vehicle asleep/wake states per OEM procedure.
Check ground continuity from module ground pin(s) to chassis; repair any high resistance ground connections.
Measure CAN_H and CAN_L idle voltages at the module connector; if voltages are out of expected range, isolate and check wiring for short-to-power/ground.
Measure the termination resistance between CAN_H and CAN_L; if open or incorrect, inspect network for missing terminator or cut wires.
If wiring and power/grounds are good, check for bus errors or fault counters with a scope or OEM network tool to identify intermittent faults.
Check SIM/antenna connectivity and module cellular registration status using OEM diagnostic functions (if applicable).
Update telematics module firmware/software if a known software fault exists or per OEM bulletin.
If module hardware is unresponsive after verifying wiring, power and network, follow OEM procedures for module replacement and post-repair network coding/reprogramming.
Clear codes and verify repair by confirming stable communication and restoration of telematics services.

Likely causes

Damaged CAN_H/CAN_L pair or connector at TCM
Ground strap or chassis ground to TCM is high resistance or open
Blown fuse or switched supply to the telematics module
CAN bus missing termination resistor or short to battery/chassis
Module software crashed or out-of-date firmware preventing network handshake
Corroded pins on multi-pin connector causing intermittent contact

Fault status

⚠️ Status

Telematics Control Module communication fault detected. Module is not responding on the vehicle network or messages are failing validation; telematics services may be unavailable.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.0-3.0 hours