AutoCodes – GMC – U1866 GMC

U1866 GMC Code - Battery Energy Control Module Lost Communication With Body 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 Body Control Module (BCM), Body Control Module harness is open or shorted, Body 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: U1866 GMC indicates Battery Energy Control Module Lost Communication With Body Control Module.
Common causes: Common causes include Faulty Body Control Module (BCM), Body Control Module harness is open or shorted, Body 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 488

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 U1866 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 U1866 GMC - Battery Energy Control Module Lost Communication With Body Control Module - AutoCodes.com — U1866 GMC Code - Battery Energy Control Module Lost Communication With Body Control Module

What does this mean?

What are the Possible Causes of the DTC U1866 GMC?

Faulty Body Control Module (BCM)
Body Control Module harness is open or shorted
Body Control Module circuit poor electrical connection

How to Fix the DTC U1866 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 U1866 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 U1866 GMC Code

1. What are the common symptoms of OBDII code U1866 in a GMC vehicle?

The common symptoms of code U1866 include issues with the battery energy control module, such as loss of communication with the body control module, warning lights on the dashboard, and potential drivability issues.

2. What could cause the OBDII code U1866 in a GMC vehicle?

The code U1866 is typically caused by a communication breakdown between the battery energy control module and the body control module. This could be due to a wiring issue, a faulty module, or a software malfunction.

3. How can I diagnose the OBDII code U1866 in my GMC vehicle?

Diagnosing code U1866 usually involves using a professional OBDII scanner to read the fault codes and then checking the connections between the battery energy control module and the body control module for any issues.

4. Can I drive my GMC vehicle with the OBDII code U1866 active?

It is not recommended to drive your vehicle with an active U1866 code, as it may lead to further electrical or drivability problems. It is best to address the issue promptly to prevent any potential damage.

5. How can I repair the OBDII code U1866 in my GMC vehicle?

To repair code U1866, you may need to inspect the wiring harness for any damage, check the connectors for corrosion or loose connections, or replace the battery energy control module if necessary.

6. Is it possible to reset the OBDII code U1866 without fixing the underlying issue?

While you can clear the fault code using an OBDII scanner, the code is likely to return if the communication issue between the modules is not resolved. It is important to address the root cause of the problem.

7. Are there any recalls or technical service bulletins related to OBDII code U1866 in GMC vehicles?

To determine if there are any recalls or technical service bulletins related to code U1866 in your specific GMC vehicle, you can contact a GMC dealership or check online resources provided by the manufacturer.

8. Can a DIY enthusiast fix the OBDII code U1866 issue in a GMC vehicle?

Depending on your level of automotive expertise, you may be able to troubleshoot and repair the U1866 code yourself by following the manufacturer's service manual or seeking guidance from online resources and forums.

9. How much does it typically cost to repair the OBDII code U1866 in a GMC vehicle?

The cost of repairing code U1866 can vary depending on the underlying issue, such as a wiring problem, faulty module, or software glitch. It is advisable to consult a professional mechanic for an accurate diagnosis and cost estimate.

10. Will fixing the OBDII code U1866 improve the overall performance and reliability of my GMC vehicle?

Addressing code U1866 and resolving the communication issue between the modules can help restore the proper functioning of the battery energy control system, ensuring the overall performance and reliability of your GMC vehicle.