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U0077 2018 GMC Sierra Code - Control Module Communication Chassis Expansion CAN Bus

Quick Answer

The U0077 code for a 2018 GMC Sierra indicates a problem with the Control Module Communication Chassis Expansion CAN Bus. Common causes include Damaged wiring or connectors in the CAN Bus network, Corrosion on the terminals of the control modules, Faulty control module related to chassis communication. 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
U0077 2018 GMC Sierra indicates Control Module Communication Chassis Expansion CAN Bus.
Common causes
Common causes include Damaged wiring or connectors in the CAN Bus network, Corrosion on the terminals of the control modules, Faulty control module related to chassis communication.
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.
What is this?
Table of contents Created and updated by William Orellana on Sep 13, 2024
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Code U0077 2018 GMC Sierra Description

The U0077 code for a 2018 GMC Sierra indicates a problem with the Control Module Communication Chassis Expansion CAN Bus. This code specifically relates to communication issues between various control modules within the vehicle's chassis, which can affect the overall performance and functionality of the vehicle. The Chassis Expansion CAN Bus is a network that allows different control modules to communicate with each other, sharing important data and commands to ensure proper operation of various systems.

OBDII Code U0077 2018 GMC Sierra - Control Module Communication Chassis Expansion CAN Bus
U0077 2018 GMC Sierra Code - Control Module Communication Chassis Expansion CAN Bus

Common Causes of U0077 2018 GMC Sierra

  1. Damaged wiring or connectors in the CAN Bus network.
  2. Corrosion on the terminals of the control modules.
  3. Faulty control module related to chassis communication.
  4. Electrical interference from aftermarket accessories or modifications.
  5. Water damage or exposure to moisture affecting the wiring.

Symptoms of U0077 2018 GMC Sierra

  1. Illumination of ABS or traction control warning lights on the dashboard.
  2. Loss of traction control or stability control functionality.
  3. Erratic behavior in the power steering system.
  4. Decreased fuel efficiency.
  5. Difficulty in shifting gears (if the transmission control module is affected).

How to Fix U0077 2018 GMC Sierra

  1. Begin by conducting a thorough inspection of the wiring harness, connectors, and control modules associated with the Chassis Expansion CAN Bus.
  2. Repair or replace any damaged wiring or connectors found during the inspection.
  3. Check for corrosion on the terminals of the control modules and clean or replace them as needed.
  4. Perform a diagnostic scan to identify the specific control module causing the communication error and address any faults within that module.
  5. Clear the U0077 code from the vehicle's computer system and test drive the vehicle to ensure proper communication and functionality of the affected systems.

Cost to Fix U0077 2018 GMC Sierra

The typical repair costs for addressing a U0077 code on a 2018 GMC Sierra can vary depending on the specific cause of the issue and the extent of the repairs needed. In general, the cost of parts for wiring repairs, connectors, or control modules can range from $100 to $500 or more. Labor costs at auto repair shops typically range from $80 to $150 per hour, with the total repair bill potentially amounting to several hundred dollars. It's important to note that rates can vary based on location, vehicle make and model, and the complexity of the repair. For a more accurate estimate, it's recommended to consult with a local auto repair shop.

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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 U0077 2018 GMC Sierra Code

1. What does the OBDII code U0077 mean on a 2018 GMC Sierra?

The U0077 code indicates a communication issue on the Control Module Communication Chassis Expansion CAN Bus, which is responsible for connecting various vehicle systems.

2. What are the common symptoms of the U0077 code on a GMC Sierra?

Symptoms may include warning lights on the dashboard, intermittent system failures, loss of functionality in certain components, or no noticeable performance issues depending on the severity.

3. What causes the U0077 code to appear?

Possible causes include damaged or corroded wiring, faulty control modules, poor connections in the CAN bus network, or a failed chassis expansion module.

4. Can the U0077 code affect drivability in a 2018 GMC Sierra?

In most cases, U0077 does not directly impact drivability, but it can lead to malfunctions in systems like stability control, braking, or other chassis-related functions.

5. How can I diagnose the U0077 code on my GMC Sierra?

Start by inspecting the CAN bus wiring for damage or corrosion, checking connections at related modules, and scanning all modules for additional fault codes to pinpoint the issue.

6. What tools are needed to troubleshoot the U0077 code?

You’ll need an OBDII scanner capable of reading manufacturer-specific codes, a multimeter for testing electrical connections, and potentially a wiring diagram for the CAN bus system.

7. Can I clear the U0077 code without repairs?

Clearing the code without addressing the root cause may work temporarily, but the problem will likely return unless the underlying issue is fixed.

8. How much does it cost to fix the U0077 code on a 2018 GMC Sierra?

Repair costs vary depending on the issue, ranging from $50 for simple wiring repairs to $500 or more for replacing a faulty control module.

9. Is the U0077 code a common issue in 2018 GMC Sierra trucks?

While not extremely common, communication errors like U0077 can occur due to wear, environmental factors, or manufacturing defects in the electrical system.

10. Can I drive my GMC Sierra with the U0077 code present?

You may be able to drive the vehicle, but it's important to address the issue promptly as it could lead to further system malfunctions or safety concerns.

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