Applicable Systems
OBD-II
Symptoms
The trailer wiring warning light is on. The trailer lights may not function correctly or the sway control may be disabled. DTC C0780 is stored in the chassis control module.
Possible Causes
- Trailer module power supply fault
- Trailer wiring short circuit
- Corroded trailer connector
- Trailer detection sensor fault
Troubleshooting Steps
- Step 1: Connect a diagnostic scanner and read chassis DTCs to confirm C0780
DTC C0780 is present with freeze frame data showing conditions when it set - Step 2: Inspect wiring and connectors in the affected circuit for corrosion, damage, or loose pins
Wiring intact, connectors clean and properly seated - Step 3: Perform component-level testing per manufacturer diagnostic procedure for the specific subsystem
Component values within specification or component confirmed faulty - Step 4: Clear the DTC and verify it does not return after a road test
DTC does not return; system warning light stays off
How to Reset
Clear the DTC after repair using a diagnostic scanner. The code will clear automatically if the fault is no longer detected after 3 consecutive drive cycles.
Frequently Asked Questions
- Q: What does code C0780 mean?
This is a chassis-related diagnostic trouble code indicating an issue with the trailer system. The specific subsystem should be diagnosed using the manufacturer's diagnostic procedure.
- Q: Can I drive with code C0780?
Limited driving is possible, but the affected chassis system may not function correctly. Have the vehicle diagnosed promptly to ensure safety systems like ABS and stability control are operational.
Source: SAE J2012 Standard OBD-II Diagnostic Trouble Codes
Category: OBD-II