U1556 Code - Chassis Control Module Lost Communication With Trailer Brake Power Control Module On LIN Bus
Quick Answer
The Local Interconnect Network (LIN) Bus consists of a single wire with a transmission rate of 10.417 Kbit/s. Common causes include Faulty Trailer Brake Power Control Module, Trailer Brake Power Control Module harness is open or shorted, Trailer Brake Power Control Module circuit poor electrical connection. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.
- What it means
- U1556 indicates Chassis Control Module Lost Communication With Trailer Brake Power Control Module On LIN Bus.
- Common causes
- Common causes include Faulty Trailer Brake Power Control Module, Trailer Brake Power Control Module harness is open or shorted, Trailer Brake Power Control Module circuit poor electrical connection.
- Severity
- High - diagnose this code as soon as possible.
- Can I drive?
- Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.
Code U1556 Description
What are the Possible Causes of the DTC U1556?
- Faulty Trailer Brake Power Control Module
- Trailer Brake Power Control Module harness is open or shorted
- Trailer Brake Power Control Module circuit poor electrical connection
- Faulty Chassis Control Module
How to Fix the DTC U1556?
Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.
What is the Cost to Diagnose the Code?
Labor: 1.0
To diagnose the U1556 code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.
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Information for Specific Makes
- U1556 Buick — Chassis Control Module Lost Communication With Trailer Brake Power Control Module On LIN Bus
- U1556 Cadillac — Chassis Control Module Lost Communication With Trailer Brake Power Control Module On LIN Bus
- U1556 Chevrolet — Chassis Control Module Lost Communication With Trailer Brake Power Control Module On LIN Bus
- U1556 GMC — Chassis Control Module Lost Communication With Trailer Brake Power Control Module On LIN Bus
Frequently Asked Questions about U1556 Code
1. What does OBDII code U1556 mean?
Code U1556 indicates the Chassis Control Module has lost communication with the Trailer Brake Power Control Module via the LIN Bus.
2. What are common symptoms of code U1556?
Symptoms may include a trailer brake warning light, inoperative trailer brakes, or erratic trailer brake performance.
3. What causes code U1556 to appear?
Common causes include a faulty Trailer Brake Power Control Module, damaged wiring or connectors in the LIN Bus circuit, or a malfunctioning Chassis Control Module.
4. Can I still drive with code U1556 active?
Yes, you can drive, but towing a trailer may be unsafe due to the potential loss of trailer brake function.
5. How do I diagnose code U1556?
Start by inspecting the wiring and connectors between the Chassis Control Module and the Trailer Brake Power Control Module for damage, corrosion, or loose connections.
6. Can a blown fuse cause code U1556?
Yes, a blown fuse in the circuit powering the Trailer Brake Power Control Module can disrupt communication and trigger this code.
7. How is code U1556 typically fixed?
Repairs may involve replacing the Trailer Brake Power Control Module, repairing damaged wiring, or reprogramming the Chassis Control Module if necessary.
8. Is code U1556 specific to certain vehicles?
This code is commonly found in vehicles equipped with trailer brake systems and may vary slightly in interpretation depending on the manufacturer.
9. Can software updates resolve code U1556?
In some cases, a software update for the Chassis Control Module or Trailer Brake Power Control Module may resolve communication issues.
10. How much does it cost to fix code U1556?
Repair costs vary but typically range from $100 to $600, depending on whether the issue is a wiring repair, module replacement, or reprogramming.
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