AutoCodes – Cadillac – U0077 Cadillac

U0077 Cadillac Code - Control Module Communication Chassis Expansion CAN Bus

Quick Answer

The devices connected to the chassis high speed General Motor Local Area Network (GMLAN) serial data circuits monitor for serial data communications during normal vehicle operation. Common causes include Check for more codes, Faulty Control Module, Control Module harness is open or shorted. 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 Cadillac indicates Control Module Communication Chassis Expansion CAN Bus.
Common causes: Common causes include Check for more codes, Faulty Control Module, Control Module harness is open or shorted.
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 5,018

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

What is this?

Table of contents Created and updated by William Orellana on Jul 20, 2023

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code U0077 Cadillac Description

The devices connected to the chassis high speed General Motor Local Area Network (GMLAN) serial data circuits monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the devices when the ignition switch is in any position other than OFF. The chassis high speed GMLAN serial data bus uses terminating resistors that are in parallel with the chassis high speed GMLAN (+) and (-) circuits. The Diagnostic Trouble Code (DTC) sets when a supervised periodic message that includes the transmitter device availability has not been received.

OBDII Code U0077 Cadillac - Control Module Communication Chassis Expansion CAN Bus - AutoCodes.com — U0077 Cadillac Code - Control Module Communication Chassis Expansion CAN Bus

What does this mean?

What are the Possible Causes of the DTC U0077 Cadillac?

Check for more codes
Faulty Control Module
Control Module harness is open or shorted
Control Module circuit poor electrical connection

How to Fix the DTC U0077 Cadillac?

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 U0077 Cadillac 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 U0077 Cadillac Code

1. What are common symptoms of OBDII code U0077 in a Cadillac related to Control Module Communication Chassis Expansion CAN Bus?

Common symptoms include issues with the chassis control module, ABS system, traction control, and stability control.

2. What are possible causes of OBDII code U0077 in a Cadillac?

Possible causes include faulty chassis control module, issues with the CAN bus communication network, damaged wiring harness, or a malfunctioning ABS module.

3. How can I diagnose OBDII code U0077 in a Cadillac?

Diagnosis typically involves using a professional OBDII scanner to retrieve the trouble codes, inspecting the chassis control module and CAN bus connections, and performing a thorough inspection of the wiring harness for any damage.

4. Can OBDII code U0077 in a Cadillac be repaired at home?

Some repairs, such as checking and securing connections or replacing damaged wiring, can be done at home. However, diagnosing and repairing complex issues related to the chassis control module may require professional expertise.

5. Is it safe to continue driving with OBDII code U0077 in a Cadillac?

It is not recommended to drive the vehicle with unresolved U0077 code as it may affect the proper functioning of crucial safety systems like ABS, traction control, and stability control.

6. Will resetting the trouble codes make OBDII code U0077 disappear permanently?

Resetting the trouble codes may temporarily clear the code, but if the underlying issue causing U0077 is not addressed, the code is likely to reappear once the problem resurfaces.

7. How much does it typically cost to repair OBDII code U0077 in a Cadillac?

The cost of repair can vary depending on the specific cause of the issue. Simple fixes like securing loose connections may be inexpensive, while replacing the chassis control module or repairing the CAN bus network can be more costly.

8. Can a faulty wheel speed sensor trigger OBDII code U0077 in a Cadillac?

While a faulty wheel speed sensor is not a direct cause of U0077, it can contribute to communication errors within the chassis control module and trigger related trouble codes.

9. Will a low battery voltage trigger OBDII code U0077 in a Cadillac?

Low battery voltage can disrupt the communication between control modules and potentially trigger code U0077. Ensuring the battery is in good condition is important for proper system operation.

10. How important is it to address OBDII code U0077 promptly in a Cadillac?

Addressing U0077 promptly is crucial as it can affect the functionality of essential safety systems in the vehicle, potentially compromising driver and passenger safety.