Code
B29E1
Generic
B — Body
Heated Seat Control Module Communication Fault
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AI status
Completed
Completed
100%
Causes
- Faulty heated seat control module
- Loss of power or ground to the heated seat module
- Open, short or high-resistance communication wiring (CAN or LIN)
- Damaged or corroded connector at the seat module
- Bus termination resistor open or shorted, improper network topology
- Fault in another module pulling the bus down (bus off)
Symptoms
- Heated seat controls inoperative or unresponsive
- Driver/passenger seat heating indicator lamp inoperative or dash message for seat system
- Related comfort features (seat memory, ventilation) not working
- Multiple body modules reporting communication errors
- Stored DTC present and may return immediately after clearing
What to check
- Verify code and freeze-frame/installation data with a scan tool
- Check for other network U-codes or body module communication DTCs
- Visually inspect seat connector(s) for corrosion, water intrusion, damaged pins
- Check battery voltage at module connector with ignition on
- Verify ground integrity at module ground(s)
- Look for signs of recent repairs or aftermarket equipment near seat wiring
Signal parameters
- Network type: typically CAN or LIN depending on vehicle (confirm with wiring diagram)
- CAN idle voltages: CAN_H ≈ 2.5 V, CAN_L ≈ 2.5 V (recessive); dominant state shows ~1–2 V differential (CAN_H higher, CAN_L lower)
- LIN idle: ~12 V (pull-up to battery) and pulses to ~0 V for data; data baud commonly 19.2 kbps to 20 kbps
- Expected message IDs: manufacturer-specific seat module IDs (check service documentation)
- Bus termination: combined end-to-end resistance ≈ 60 Ω on CAN bus (two 120 Ω resistors in parallel)
Diagnostic algorithm
- Retrieve DTC(s) and freeze-frame data; note ignition state and module wake conditions
- Check for other communication DTCs (U-codes) that indicate wider bus issues
- Visually inspect heated seat module connector and harness for damage, corrosion, or water intrusion; repair as needed
- With ignition ON, verify battery voltage at module power pin(s) and measure ground continuity to chassis ground
- Using DVOM, confirm presence and correct idle voltages on communication lines (CAN_H, CAN_L or LIN) at the module connector
- If voltages abnormal, backprobe harness and trace toward gateway/module to locate short/open; repair wiring or connectors
- Measure bus resistance (power off): expected ~60 Ω across CAN_H to CAN_L; open or very high indicates missing termination; low short to power/ground indicates shorts
- Use an oscilloscope to view communication waveform while network active: look for valid frames, noise, or a dominant bus-off condition
- Disconnect the heated seat module and monitor bus behavior: if bus returns to normal, suspect module; if not, disconnect other modules on same bus to isolate defective unit
- If wiring/power/grounds OK and module isolated as faulty, replace or reprogram module per service procedure
- After repairs, clear codes, perform relearn/initialization steps if required, and verify function and that code does not return
Likely causes
- Lost or intermittent battery power/ground at seat control module
- Damaged communication wiring (pin damage, chafing, connector corrosion)
- Module internal failure
- Another module on the same bus causing bus errors (bus off)
Fault status
Status
Communication fault: heated seat control module not responding on the vehicle network. Possible wiring, power/ground, or module failure.
Repair difficulty: Medium
Diagnostic time: 1-3 hours
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