U1556
Chassis Control Module Lost Communication With Trailer Brake Power Control Module On LIN Bus
U1556 is an OBD-II diagnostic trouble code meaning: Chassis Control Module Lost Communication With Trailer Brake Power Control Module On LIN Bus. Common causes: open or short circuit in lin bus, trailer brake control module (tbpcm) malfunction. Estimated repair cost: $17–89.
Symptoms
- Check Engine light comes on
- No response from trailer brakes
- Errors in the chassis control system
- Reduced functionality when towing
Causes
- Open or short circuit in LIN bus
- Trailer Brake Control Module (TBPCM) malfunction
- TBPCM power supply problems
- Damage to connectors or corrosion of contacts
- Chassis control module (CCM) malfunction
How to Fix
- Check the integrity of the LIN bus and the condition of the connectors
- Check the power and ground of the TBPCM module
- Scan modules for additional errors
- If necessary, replace the faulty module or wiring
- Reprogram modules if necessary
Related codes
FAQ
What does the U1556 code mean?
U1556 is an OBD-II diagnostic trouble code that indicates: Chassis Control Module Lost Communication With Trailer Brake Power Control Module On LIN Bus
What causes a U1556 error code?
The most common causes of U1556 include: Open or short circuit in LIN bus; Trailer Brake Control Module (TBPCM) malfunction; TBPCM power supply problems; Damage to connectors or corrosion of contacts.
How do I fix a U1556 diagnostic trouble code?
To fix U1556: Check the integrity of the LIN bus and the condition of the connectors. Check the power and ground of the TBPCM module. Scan modules for additional errors. For a complete diagnosis, use an OBD-II scanner.
Is it safe to drive with U1556?
Do not drive — repair immediately
How much does it cost to fix U1556?
The estimated repair cost for U1556 is $17–89. Actual cost depends on your vehicle, location, and labor rates.
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