Lost Communication With Trailer Body Control Module
The U0203 code means the vehicle's onboard diagnostic system has detected: Lost Communication With Trailer Body Control Module. This is a low severity code.
- Keep driving?
- Yes, but fix soon
- DIY difficulty
- moderate
- Estimated cost
- $100 - $400 (parts and labor)
Network codes mean modules are not communicating. You need a scanner that reads all systems to find the problem.
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Common Symptoms
- Trailer lights not functioning
- Trailer turn signals inoperative
- No communication with trailer module
- Trailer running lights flickering
Probable Causes (Ranked by Likelihood)
- Corroded trailer connector Very High
- Damaged trailer wiring harness High
- Failed trailer body module Moderate
- Blown trailer light fuse Low
Step-by-Step Diagnostic Procedure
-
Clean and inspect 7-pin trailer connector
-
Check trailer wiring harness for damage
-
Verify trailer fuse in tow vehicle fuse box
-
Test for CAN bus signal at trailer plug
Frequently Asked Questions
Can I tow with U0203?
You can tow short distances at reduced speeds, but trailer lights may not function which is a safety concern.
What causes U0203?
Corroded trailer connector pins are the most common cause from road salt and moisture exposure.
How much does U0203 cost to fix?
Usually $100 to $400. Connector cleaning is cheap but harness repair costs more.
Sources
This page is built from documented references. Verify against your own service info before repair work.
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