AutoCodes – Generic – U1838

U1838 Code - Lost Communication With Battery Charger Control Module On High Voltage Energy Management CAN Bus

Quick Answer

The serial data circuit is the means by which the devices in the vehicle communicate with each other. Common causes include Faulty Battery Charger Control Module, Battery Charger Control Module harness is open or shorted, Battery Charger 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: U1838 indicates Lost Communication With Battery Charger Control Module On High Voltage Energy Management CAN Bus.
Common causes: Common causes include Faulty Battery Charger Control Module, Battery Charger Control Module harness is open or shorted, Battery Charger 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 1,305

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 07, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code U1838 Description

The serial data circuit is the means by which the devices in the vehicle communicate with each other. Once the scan tool is connected to the serial data circuit through the Data Link Connector (DLC), the scan tool can be used to monitor each device for diagnostic purposes and to check for Diagnostic Trouble Code (DTC). When the vehicle is ON, each device communicating on the serial data circuit sends a state of health message to ensure that the device is operating properly. When a device stops communicating on the serial data circuit, for example, if the device loses power or ground, the state of health message it normally sends on the serial data circuit disappears. Other devices on the serial data circuit, which expect to receive that state of the health message, detect its absence; those devices in turn set a DTC associated with the loss of the state of health of the non-communicating device. A loss of serial data communications DTC does not represent a failure of the devices that contain the stored DTC. The DTC will set when a supervised periodic message that includes the transmitter device availability has not been received.

OBDII Code U1838 - Lost Communication With Battery Charger Control Module On High Voltage Energy Management CAN Bus - AutoCodes.com — U1838 Code - Lost Communication With Battery Charger Control Module On High Voltage Energy Management CAN Bus

What does this mean?

What are the Possible Causes of the DTC U1838?

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

How to Fix the DTC U1838?

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 U1838 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 U1838 code?

Need more information on how to fix the U1838 code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the U1838 code diagnosed by a professional: Find a repair shop in your area

Information for Specific Makes

U1838 Buick — Lost Communication With Battery Charger Control Module On High Voltage Energy Management CAN Bus
U1838 Cadillac — Lost Communication With Battery Charger Control Module On High Voltage Energy Management CAN Bus
U1838 Chevrolet — Lost Communication With Battery Charger Control Module On High Voltage Energy Management CAN Bus
U1838 GMC — Lost Communication With Battery Charger Control Module On High Voltage Energy Management CAN Bus

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 U1838 Code

1. What are common symptoms of OBDII code U1838?

- Common symptoms include the inability to charge the high voltage battery, the vehicle not starting or running properly, and warning lights related to the high voltage energy management system.

2. What can cause OBDII code U1838 to occur?

- This code is typically triggered when there is a communication failure between the battery charger control module and the high voltage energy management CAN bus. Possible causes include wiring issues, a faulty battery charger control module, or problems with the CAN bus network.

3. How can I diagnose the root cause of OBDII code U1838?

- To diagnose the issue, it is recommended to perform a thorough inspection of the wiring harness connecting the battery charger control module to the CAN bus network. Additionally, using a diagnostic scanner to check for any other related trouble codes can help pinpoint the problem.

4. Is it safe to continue driving with OBDII code U1838 present?

- It is not recommended to drive the vehicle with this code present, as it may lead to further issues with the high voltage energy management system. It is best to address the problem promptly to ensure the vehicle's safety and performance.

5. Can I repair OBDII code U1838 myself?

- Repairing this code may require advanced diagnostic tools and knowledge of high voltage systems. It is recommended to seek assistance from a qualified technician or a dealership specializing in hybrid or electric vehicles to properly diagnose and repair the issue.

6. How much does it typically cost to repair OBDII code U1838?

- The cost of repairing this code can vary depending on the root cause of the issue. It may range from a few hundred to a few thousand dollars, considering the cost of parts and labor involved in diagnosing and fixing the problem.

7. Are there any preventive measures to avoid OBDII code U1838 in the future?

- Regular maintenance of the high voltage energy management system, including checking the wiring connections and keeping the components clean, can help prevent issues that may lead to this code. Additionally, following the manufacturer's recommended service schedule is crucial.

8. Can a low or dead high voltage battery cause OBDII code U1838 to appear?

- Yes, a low or dead high voltage battery can potentially trigger this code due to the communication failure between the battery charger control module and the high voltage energy management system. Ensuring the high voltage battery is properly charged is essential in avoiding this issue.

9. How long does it take to repair OBDII code U1838?

- The repair time for this code can vary depending on the exact cause of the problem and the availability of parts. It may take a few hours to a full day to diagnose and repair the issue, so it's advisable to plan accordingly.

10. Will resetting the OBDII code U1838 fix the problem permanently?

- Simply resetting the code may temporarily clear the warning light, but it will not fix the underlying issue causing the communication failure. It is crucial to address the root cause of the problem to prevent the code from reappearing in the future.