AutoCodes – Generic – U186B

U186B Code - Electronic Brake Control Module Lost Communication With Transmission 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 Transmission Control Module (TCM), Transmission Control Module harness is open or shorted, Transmission 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: U186B indicates Electronic Brake Control Module Lost Communication With Transmission Control Module.
Common causes: Common causes include Faulty Transmission Control Module (TCM), Transmission Control Module harness is open or shorted, Transmission 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 1,572

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 U186B 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 U186B - Electronic Brake Control Module Lost Communication With Transmission Control Module - AutoCodes.com — U186B Code - Electronic Brake Control Module Lost Communication With Transmission Control Module

What does this mean?

What are the Possible Causes of the DTC U186B?

Faulty Transmission Control Module (TCM)
Transmission Control Module harness is open or shorted
Transmission Control Module circuit poor electrical connection

How to Fix the DTC U186B?

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 U186B 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

U186B Buick — Electronic Brake Control Module Lost Communication With Transmission Control Module
U186B Cadillac — Electronic Brake Control Module Lost Communication With Transmission Control Module
U186B Chevrolet — Electronic Brake Control Module Lost Communication With Transmission Control Module
U186B GMC — Electronic Brake Control Module Lost Communication With Transmission Control Module

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 U186B Code

1. What are the common symptoms of OBDII code U186B?

The common symptoms of OBDII code U186B include issues with the electronic brake control system, transmission shifting problems, warning lights on the dashboard (such as ABS or transmission warning lights), and potential loss of communication between the brake control module and the transmission control module.

2. What can cause the OBDII code U186B to trigger?

The OBDII code U186B typically triggers when there is a loss of communication between the electronic brake control module and the transmission control module. This can be caused by wiring issues, a faulty module, a software glitch, or a bad connection.

3. How serious is the OBDII code U186B?

The OBDII code U186B should be addressed promptly, as it indicates a communication problem between critical systems in the vehicle. Ignoring this issue may lead to potential safety risks, including compromised braking and shifting performance.

4. What are some DIY repair tips for OBDII code U186B?

DIY repair tips for OBDII code U186B may include checking and tightening the wiring connections between the brake control module and the transmission control module, inspecting for any visible damage to the wiring harness, and ensuring that all modules are properly seated and connected.

5. Can I drive my vehicle with the OBDII code U186B?

It is not recommended to drive your vehicle with the OBDII code U186B present, as it can affect the communication between crucial systems like the brakes and transmission. It is best to address the issue promptly to ensure safe operation of the vehicle.

6. How can a mechanic diagnose the OBDII code U186B?

A mechanic can diagnose the OBDII code U186B using a professional OBDII scanner to retrieve the specific fault codes and perform a thorough inspection of the brake control module, transmission control module, and related wiring for any signs of damage or malfunction.

7. What is the typical cost to repair OBDII code U186B?

The cost to repair OBDII code U186B can vary depending on the underlying cause of the communication issue. It may range from a simple wiring repair to module replacement, with costs typically including parts and labor.

8. Can a software update fix the OBDII code U186B?

In some cases, a software update provided by the manufacturer may address the communication issue causing the OBDII code U186B. It is recommended to consult with a qualified mechanic or dealership to determine if a software update is available for your specific vehicle.

9. Is the OBDII code U186B a common issue in certain vehicle makes and models?

The OBDII code U186B may be more commonly reported in certain vehicle makes and models, particularly those with electronic brake control systems and complex transmission control modules. It is advisable to check with your vehicle manufacturer or online forums for any known issues related to this code.

10. How can I prevent the OBDII code U186B from recurring?

To prevent the OBDII code U186B from recurring, regular maintenance and inspections of the electronic brake control module, transmission control module, and related wiring are recommended. Addressing any potential issues promptly can help prevent communication breakdowns between these critical systems.