AutoCodes – Chevrolet – U1556 Chevrolet

U1556 Chevrolet 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 Chevrolet 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.

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Code Popularity 1,545

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

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Table of contents Created and updated by William Orellana on Jun 04, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code U1556 Chevrolet Description

The Local Interconnect Network (LIN) Bus consists of a single wire with a transmission rate of 10.417 Kbit/s. The serial data is transmitted over a LIN circuit between a master control module and other LIN devices within a particular subsystem. If serial data communication is lost between any of the LIN devices on the LIN bus network, the master control module will set a no communication code against the non-communicating LIN device. The Diagnostic Trouble Code (DTC) will set when a supervised periodic message to the Chassis Control Module from the Trailer Brake Power Control Module has not been received.

OBDII Code U1556 Chevrolet - Chassis Control Module Lost Communication With Trailer Brake Power Control Module On LIN Bus - AutoCodes.com — U1556 Chevrolet Code - Chassis Control Module Lost Communication With Trailer Brake Power Control Module On LIN Bus

What does this mean?

What are the Possible Causes of the DTC U1556 Chevrolet?

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 Chevrolet?

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 Chevrolet 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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About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.

Frequently Asked Questions about U1556 Chevrolet Code

What does the OBDII code U1556 mean for my Chevrolet vehicle?

The U1556 code indicates a lost communication between the Chassis Control Module and the Trailer Brake Power Control Module on the Local Interconnect Network (LIN) bus.

What are the symptoms of the U1556 code?

Common symptoms include warning lights on the dashboard, issues with trailer braking, and potential malfunctions in the vehicle's chassis control systems.

What could cause the U1556 code to trigger?

Possible causes include damaged wiring or connectors, a faulty Trailer Brake Power Control Module, issues with the Chassis Control Module, or communication problems on the LIN bus.

How can I diagnose the U1556 code?

Start by using an OBDII scanner to confirm the code. Inspect the wiring and connectors related to the Trailer Brake Power Control Module and check for any corrosion or damage.

Can I fix the U1556 code myself?

If you have experience with automotive electrical systems, you can inspect and repair wiring and connectors. However, if the issue is with the modules themselves, it may be best to consult a professional mechanic.

What should I do if I see the U1556 code?

Begin by checking for any visible damage to the trailer brake wiring and connectors. If everything looks good, consider having the modules tested for faults.

Is it safe to drive my vehicle with the U1556 code?

While you can drive the vehicle, it may not be safe to tow a trailer until the issue is resolved, as braking performance could be compromised.

How much does it typically cost to repair the issue associated with the U1556 code?

Repair costs can vary widely depending on the cause; simple wiring repairs may cost less than $100, whereas module replacements could exceed $500.

What is the role of the Trailer Brake Power Control Module?

The Trailer Brake Power Control Module manages the braking system for trailers, ensuring proper brake application and functionality when towing.

Will clearing the U1556 code fix the problem?

Clearing the code may temporarily turn off the check engine light, but it will not fix the underlying issue. The code will likely reappear if the root cause is not addressed.