AutoCodes – GMC – U186A GMC

U186A GMC Code - Electronic Brake Control Module Lost Communication With Engine Control Module

Quick Answer

Modules connected to the Controller Area Network (CAN) serial data circuits monitor for serial data communications during normal vehicle operation. Common causes include Faulty Engine Control Module (ECM), Engine Control Module harness is open or shorted, Engine 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: U186A GMC indicates Electronic Brake Control Module Lost Communication With Engine Control Module.
Common causes: Common causes include Faulty Engine Control Module (ECM), Engine Control Module harness is open or shorted, Engine 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 746

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 Jun 08, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code U186A GMC Description

Modules connected to the Controller Area Network (CAN) serial data circuits monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the modules. The modules have prerecorded information about what messages are needed to be exchanged on the serial data circuits. The messages are supervised and also, some periodic messages are used by the receiver module as an availability indication of the transmitter module. Each message contains the identification number of the transmitter module. A module with a CAN serial data circuits malfunction or which loses power during the current ignition cycle will have a Loss of Communication Diagnostic Trouble Code (DTC) set by other modules that depend on information from that failed module. If any of the CAN circuit are shorted to battery voltage, ground, or between them no communication is possible on the CAN serial data bus, a Diagnostic Trouble Code will set.

OBDII Code U186A GMC - Electronic Brake Control Module Lost Communication With Engine Control Module - AutoCodes.com — U186A GMC Code - Electronic Brake Control Module Lost Communication With Engine Control Module

What does this mean?

What are the Possible Causes of the DTC U186A GMC?

Faulty Engine Control Module (ECM)
Engine Control Module harness is open or shorted
Engine Control Module circuit poor electrical connection

How to Fix the DTC U186A GMC?

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 U186A GMC 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 U186A GMC Code

1. What are the common symptoms of OBDII code U186A GMC?

- Common symptoms include the ABS warning light coming on, traction control issues, and potential loss of communication between the electronic brake control module and engine control module.

2. What causes the OBDII code U186A GMC to appear?

- The code U186A typically indicates a loss of communication between the electronic brake control module and the engine control module, which can be caused by wiring issues, faulty modules, or software glitches.

3. How can I diagnose the cause of code U186A GMC?

- Diagnosing this code usually involves inspecting the wiring harness between the electronic brake control module and engine control module, checking for loose connections, and using a diagnostic scanner to identify communication faults.

4. Can a DIYer repair the U186A GMC code?

- While some DIYers may be able to address this code by checking and repairing wiring connections, it is recommended to consult a professional mechanic with experience in diagnosing and repairing communication issues between modules.

5. Is it safe to drive with the U186A GMC code present?

- It is not recommended to drive with the U186A code present, as it can affect the proper functioning of the electronic brake control system, potentially compromising vehicle safety.

6. How much does it typically cost to repair the U186A GMC code?

- Repair costs for the U186A code can vary depending on the underlying cause. It is advisable to obtain a diagnosis from a qualified mechanic to determine the exact repair costs.

7. Can a faulty ABS sensor trigger the U186A GMC code?

- While a faulty ABS sensor can cause related issues, the U186A code specifically points to a communication problem between the electronic brake control module and engine control module, rather than a sensor issue.

8. Are there any preventive measures to avoid the U186A GMC code?

- Regular maintenance checks, ensuring proper wiring connections, and promptly addressing any warning lights related to the brake system can help prevent the occurrence of the U186A code.

9. Will resetting the trouble codes make the U186A GMC code disappear?

- Resetting the trouble codes may temporarily clear the U186A code, but if the underlying communication issue between modules persists, the code is likely to reappear after driving the vehicle.

10. How urgent is it to address the U186A GMC code?

- It is important to address the U186A code promptly to ensure the proper functioning of the electronic brake control system and avoid potential safety risks associated with a loss of communication between critical modules.