AutoCodes – Generic – U1866

U1866 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 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 1,032

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

What does this mean?

What are the Possible Causes of the DTC U1866?

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?

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 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.

Need more information about the U1866 code?

Need more information on how to fix the U1866 code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the U1866 code diagnosed by a professional: Find a repair shop in your area

Information for Specific Makes

U1866 Buick — Battery Energy Control Module Lost Communication With Body Control Module
U1866 Cadillac — Battery Energy Control Module Lost Communication With Body Control Module
U1866 Chevrolet — Battery Energy Control Module Lost Communication With Body Control Module
U1866 GMC — Battery Energy Control Module Lost Communication With Body 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 U1866 Code

1. What are common symptoms of OBDII code U1866?

- Common symptoms include issues with the battery, power loss, communication errors between modules, and warning lights on the dashboard.

2. What can cause the OBDII code U1866 to appear?

- The code may be triggered by a faulty battery energy control module, a malfunctioning body control module, loose or corroded wiring connections, or software issues.

3. How can I diagnose the U1866 code?

- Diagnosis involves using an OBDII scanner to retrieve the specific code, checking the battery energy control module and body control module for communication errors, and inspecting wiring for damage.

4. What are some repair tips for resolving code U1866?

- Repair tips include checking and repairing any loose or corroded wiring connections, ensuring proper power supply to the modules, and reprogramming or replacing the affected modules if necessary.

5. Can I drive my vehicle with code U1866 present?

- It is not recommended to drive the vehicle with this code present, as it can lead to further electrical issues and potential safety hazards.

6. How much does it cost to repair OBDII code U1866?

- The cost of repair can vary depending on the underlying cause, but it may involve replacing modules, repairing wiring, and reprogramming the system, which can range from a few hundred to over a thousand dollars.

7. How long does it take to fix the U1866 code?

- The repair time can vary based on the complexity of the issue, but it may take a few hours to a full day to diagnose and repair the problem causing the U1866 code.

8. Can I clear the U1866 code with an OBDII scanner?

- Yes, you can clear the U1866 code with an OBDII scanner, but it is important to address the underlying issue causing the code to prevent it from reoccurring.

9. Will the U1866 code reset itself after repair?

- After repairing the underlying issue causing the U1866 code, you may need to clear the code manually with an OBDII scanner to reset it and ensure proper functionality of the vehicle.

10. Is it safe to continue driving if the U1866 code disappears on its own?

- Even if the U1866 code disappears on its own, it is still recommended to have the vehicle inspected by a professional to confirm that the issue has been resolved and prevent any further problems.