What does this code mean?
The wording below belongs to the named make and communication. Match the complete code, reporting module, model year and engine before applying it.
A code identifies a detected condition, not a part that must automatically be replaced.
Manufacturer communications
2Original wording in English
CHEVROLET, GMC
Reported code forms U1556
This Preliminary Information communication provides information to the technician about vehicles that have Trailer connection not recognized or “Check Trailer wiring” or “Service Trailer Brake” message. Technician may…
CHEVROLET, GMC
Reported code forms U1556
This Preliminary Information communication provides information to the technician about vehicles that have Trailer connection not recognized or ?Check Trailer wiring? or ?Service Trailer Brake? message. Technician may…
Check vehicle applicability
42A listed vehicle is a research lead. Confirm the engine, production range and software in the manufacturer's information.
| Make | Model | Model year |
|---|---|---|
| Chevrolet | SILVERADO | 2017 |
| Chevrolet | SILVERADO 1500 | 2018 |
| Chevrolet | SILVERADO 1500 | 2017 |
| Chevrolet | SILVERADO 1500 | 2016 |
| Chevrolet | SILVERADO 1500 | 2015 |
| Chevrolet | SILVERADO 1500 | 2014 |
| Chevrolet | SILVERADO 2500 | 2018 |
| Chevrolet | SILVERADO 2500 | 2017 |
| Chevrolet | SILVERADO 2500 | 2016 |
| Chevrolet | SILVERADO 2500 | 2015 |
| Chevrolet | SILVERADO 3500 | 2018 |
| Chevrolet | SILVERADO 3500 | 2017 |
Before replacing a part
Record codes and freeze-frame data. Check battery condition, related codes and visible wiring or hose damage. Follow the vehicle's diagnostic procedure and test results before replacing parts.
Can I keep driving?
A code alone cannot establish whether driving is safe. A flashing malfunction light, severe shaking, overheating, oil-pressure warning or loss of braking or steering needs prompt attention. Stop in a safe place and seek assistance when control or engine safety is affected. Follow the vehicle handbook.