What are the common causes of U0137?

A wiring fault between the vehicle and the Trailer Brake Control Module. A failed Trailer Brake Control Module. Low battery voltage or a weak alternator. A poor trailer connection or a faulty trailer harness.

Scan all modules for communication codes. Check battery voltage and the charging system. Inspect the wiring between the vehicle and the Trailer Brake Control Module. Check the trailer connection and trailer harness. Replace the Trailer Brake Control Module if the bus and feeds test good. Clear the code and retest.

U0137

Lost Communication With Trailer Brake Control Module

System: Network communication (U code)
Lamp: Check Engine Light
Category: Network Communications

What it means

U0137 means Lost Communication With Trailer Brake Control Module.

Where it lives

For U0137, start at the module the description names.

Check these first

A wiring fault between the vehicle and the Trailer Brake Control Module
A failed Trailer Brake Control Module
Low battery voltage or a weak alternator
A poor trailer connection or a faulty trailer harness

What to do next

Scan all modules for communication codes
Check battery voltage and the charging system
Inspect the wiring between the vehicle and the Trailer Brake Control Module
Check the trailer connection and trailer harness
Replace the Trailer Brake Control Module if the bus and feeds test good
Clear the code and retest

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Updated

Generic SAE J2012 definition. Last updated 2026-10-10.