AutoCodes – Cadillac – U1878 Cadillac

U1878 Cadillac Code - Drive Motor B Control Module Lost Communication With Battery Energy Control Module

Quick Answer

Devices connected to the serial data circuits monitor for serial data communications during normal vehicle operation. Common causes include Faulty Battery Energy Control Module, Battery Energy Control Module harness is open or shorted, Battery Energy 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: U1878 Cadillac indicates Drive Motor B Control Module Lost Communication With Battery Energy Control Module.
Common causes: Common causes include Faulty Battery Energy Control Module, Battery Energy Control Module harness is open or shorted, Battery Energy 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 637

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 U1878 Cadillac Description

Devices connected to the serial data circuits monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the devices. The devices have prerecorded information about what messages are needed to be exchanged on the serial data circuits, for each virtual network. The messages are supervised and also, some periodic messages are used by the receiver device as an availability indication of the transmitter device. Each message contains the identification number of the transmitter device. The Diagnostic Trouble Code (DTC) will set if a supervised periodic message that includes the transmitter device availability has not been received.

OBDII Code U1878 Cadillac - Drive Motor B Control Module Lost Communication With Battery Energy Control Module - AutoCodes.com — U1878 Cadillac Code - Drive Motor B Control Module Lost Communication With Battery Energy Control Module

What does this mean?

What are the Possible Causes of the DTC U1878 Cadillac?

Faulty Battery Energy Control Module
Battery Energy Control Module harness is open or shorted
Battery Energy Control Module circuit poor electrical connection

How to Fix the DTC U1878 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 U1878 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 U1878 Cadillac Code

1. What are the common symptoms of OBDII code U1878 in a Cadillac?

- Common symptoms include loss of communication between the drive motor B control module and the battery energy control module, resulting in various electrical issues in the vehicle.

2. What are the possible causes of OBDII code U1878 in a Cadillac?

- The code U1878 typically indicates a communication error between the drive motor B control module and the battery energy control module, which can be caused by wiring issues, faulty modules, or a weak battery.

3. How serious is OBDII code U1878 in a Cadillac?

- The severity of the code U1878 depends on the extent of the communication loss between the modules. While it may not directly affect the drivability of the vehicle, it can lead to other electrical problems if left unresolved.

4. Can I still drive my Cadillac with OBDII code U1878 present?

- It is generally not recommended to drive the vehicle with unresolved OBDII code U1878, as it can cause further electrical issues and potentially impact the vehicle's performance.

5. How can I diagnose OBDII code U1878 in my Cadillac?

- Diagnosing code U1878 typically involves using a professional OBDII scanner to retrieve the specific details of the communication error and inspecting the wiring and connections between the modules for any faults.

6. What are some repair tips for fixing OBDII code U1878 in a Cadillac?

- Repair tips may include checking and repairing any damaged wiring, ensuring proper connections between the modules, and, if necessary, replacing the faulty drive motor B control module or battery energy control module.

7. Can a DIY enthusiast fix OBDII code U1878 in a Cadillac?

- While some basic troubleshooting steps can be taken by a DIY enthusiast, resolving OBDII code U1878 may require specialized tools and expertise, making it advisable to consult a professional mechanic.

8. How much does it cost to repair OBDII code U1878 in a Cadillac?

- Repair costs for OBDII code U1878 can vary depending on the specific cause of the communication error and the necessary repairs. It is recommended to obtain a diagnostic assessment from a qualified mechanic for an accurate cost estimate.

9. Will resetting the OBDII code U1878 in my Cadillac make it go away permanently?

- Resetting the code may temporarily clear the fault, but if the underlying issue causing the communication error between the modules is not addressed, the code is likely to reappear.

10. Is it safe to ignore OBDII code U1878 in a Cadillac?

- Ignoring OBDII code U1878 is not recommended, as it can lead to further electrical problems and potentially affect the overall performance and safety of the vehicle.