AutoCodes – GMC – U1803 GMC

U1803 GMC Code - Lost Communication with Hybrid/EV Powertrain Control Module 2

Quick Answer

The serial data circuit is the means by which the devices in the vehicle communicate with each other. Common causes include Faulty Hybrid/EV Powertrain Control Module 2, Hybrid/EV Powertrain Control Module 2 harness is open or shorted, Hybrid/EV Powertrain Control Module 2 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: U1803 GMC indicates Lost Communication with Hybrid/EV Powertrain Control Module 2.
Common causes: Common causes include Faulty Hybrid/EV Powertrain Control Module 2, Hybrid/EV Powertrain Control Module 2 harness is open or shorted, Hybrid/EV Powertrain Control Module 2 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 492

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 Jul 21, 2023

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code U1803 GMC 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 Codes (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 health message, detect its absence; those devices in turn set a DTC associated with the loss of 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.

OBDII Code U1803 GMC - Lost Communication with Hybrid/EV Powertrain Control Module 2 - AutoCodes.com — U1803 GMC Code - Lost Communication with Hybrid/EV Powertrain Control Module 2

What does this mean?

What are the Possible Causes of the DTC U1803 GMC?

Faulty Hybrid/EV Powertrain Control Module 2
Hybrid/EV Powertrain Control Module 2 harness is open or shorted
Hybrid/EV Powertrain Control Module 2 circuit poor electrical connection

How to Fix the DTC U1803 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 U1803 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.

Need more information about the U1803 GMC code?

Need more information on how to fix the U1803 GMC code? Get Access to Factory Service Manuals

Need Help with the Code?

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Information for Specific GMC Models

U1803 2014 GMC Sierra — Lost Communication with Hybrid/EV Powertrain Control Module 2
U1803 2015 GMC Sierra — Lost Communication with Hybrid/EV Powertrain Control Module 2
U1803 2016 GMC Sierra — Lost Communication with Hybrid/EV Powertrain Control Module 2
U1803 2017 GMC Sierra — Lost Communication with Hybrid/EV Powertrain Control Module 2
U1803 2018 GMC Sierra — Lost Communication with Hybrid/EV Powertrain Control Module 2

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 U1803 GMC Code

1. What are the common symptoms of OBDII code U1803 GMC?

The common symptoms of code U1803 GMC include the check engine light illuminating on the dashboard, loss of communication with the hybrid/EV powertrain control module 2, and potential drivability issues.

2. What can cause the OBDII code U1803 GMC to appear?

The code U1803 GMC, indicating lost communication with hybrid/EV powertrain control module 2, can be triggered by issues such as damaged wiring or connectors, a faulty control module, or software glitches.

3. How serious is the OBDII code U1803 GMC?

While code U1803 GMC may not always cause immediate drivability issues, it is important to address the underlying communication problem with the hybrid/EV powertrain control module 2 to ensure proper function of the vehicle's powertrain systems.

4. What are some potential repair tips for resolving code U1803 GMC?

To resolve code U1803 GMC, start by checking the wiring and connectors for any damage or corrosion. Resetting the fault codes and performing a software update or reprogramming the control module may also help resolve the communication issue.

5. Can I drive my vehicle with the OBDII code U1803 GMC present?

It is generally not recommended to drive your vehicle with unresolved OBDII codes, including U1803 GMC. While it may not immediately affect drivability, the underlying communication issue should be addressed to prevent potential long-term problems.

6. How can I diagnose the cause of code U1803 GMC at home?

Diagnosing the cause of code U1803 GMC may require specialized diagnostic equipment. However, you can start by checking the wiring and connectors for visible damage and ensuring they are securely connected. If the issue persists, professional diagnosis may be necessary.

7. Are there any recalls or technical service bulletins related to OBDII code U1803 GMC?

It is recommended to check with a GMC dealership or online resources for any recalls or technical service bulletins related to code U1803 GMC. Manufacturers may issue updates or remedies for common issues like communication problems with control modules.

8. How much does it typically cost to repair OBDII code U1803 GMC?

The cost of repairing code U1803 GMC can vary depending on the underlying cause. Simple fixes like repairing wiring or connectors may cost less, while replacing a control module or addressing software issues could be more expensive. It is advisable to obtain quotes from reputable repair shops.

9. Can extreme weather conditions contribute to triggering code U1803 GMC?

Extreme weather conditions, such as excessive heat or moisture, can potentially affect the electrical connections and components related to the hybrid/EV powertrain control module 2, leading to communication issues and triggering code U1803 GMC.

10. How can I prevent the recurrence of OBDII code U1803 GMC in the future?

To prevent the recurrence of code U1803 GMC, it is essential to regularly inspect and maintain the vehicle's electrical components, including wiring and connectors. Keeping the control modules updated and addressing any communication issues promptly can help prevent the code from reappearing.