AutoCodes – Generic – U1817

U1817 Code - Lost Communication with Hybrid Powertrain Control Module on Powertrain Expansion CAN Bus Malfunction

Quick Answer

Devices connected to the powertrain high-speed General Motor Local Area Network (GMLAN) serial data circuits monitor for serial data communications during normal vehicle operation. Common causes include Faulty Starter/Generator Control Module, Starter/Generator Control Module harness is open or shorted, Starter/Generator 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: U1817 indicates Lost Communication with Hybrid Powertrain Control Module on Powertrain Expansion CAN Bus Malfunction.
Common causes: Common causes include Faulty Starter/Generator Control Module, Starter/Generator Control Module harness is open or shorted, Starter/Generator 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.

Save to My Repairs My Repairs

AI answers can be wrong. Verify repairs with testing. Open full chat

Code Popularity 5,722

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 Aug 09, 2023

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
Add Comment

💬 Need more help? Ask Coddy for instant answers — it's free!

Code U1817 Description

Devices connected to the powertrain high-speed General Motor Local Area Network (GMLAN) 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 Motor Control Module and the Hybrid Powertrain Control Module are all internal to the Starter/Generator Control Module. All circuits to the Hybrid Powertrain Control Module are also internal to the Starter/Generator Control Module.
Communication diagnostics for the serial data, including device power and ground as well as the wakeup circuits for the Motor Control Module and the Hybrid Powertrain Control Module are all diagnosed from external sources only to the Starter/Generator Control Module connector because any circuit fault condition within the Starter/Generator Control Module will cause a complete replacement.
The Diagnostic Trouble Code (DTC) will be set when a supervised periodic message that includes the transmitter device availability has not been received.

OBDII Code U1817 - Lost Communication with Hybrid Powertrain Control Module on Powertrain Expansion CAN Bus Malfunction - AutoCodes.com — U1817 Code - Lost Communication with Hybrid Powertrain Control Module on Powertrain Expansion CAN Bus Malfunction

What does this mean?

What are the Possible Causes of the DTC U1817?

Faulty Starter/Generator Control Module
Starter/Generator Control Module harness is open or shorted
Starter/Generator Control Module circuit poor electrical connection

How to Fix the DTC U1817?

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 U1817 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 U1817 code?

Need more information on how to fix the U1817 code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the U1817 code diagnosed by a professional: Find a repair shop in your area

Information for Specific Makes

U1817 Buick — Lost Communication with Hybrid Powertrain Control Module on Powertrain Expansion CAN Bus Malfunction
U1817 Cadillac — Lost Communication with Hybrid Powertrain Control Module on Powertrain Expansion CAN Bus Malfunction
U1817 Chevrolet — Lost Communication with Hybrid Powertrain Control Module on Powertrain Expansion CAN Bus Malfunction
U1817 GMC — Lost Communication with Hybrid Powertrain Control Module on Powertrain Expansion CAN Bus Malfunction

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 U1817 Code

1. What are the common symptoms of OBDII code U1817?

Symptoms may include the hybrid powertrain system not functioning properly, loss of power or acceleration, warning lights illuminated on the dashboard, and potential vehicle stalling.

2. What can cause the U1817 code to trigger?

The U1817 code is typically triggered by a malfunction in the Powertrain Expansion Controller Area Network (CAN) communication system, often due to wiring issues, a faulty powertrain control module, or a problem with the hybrid powertrain control module.

3. How do I diagnose the U1817 code?

Diagnosing the U1817 code involves checking the wiring and connectors related to the hybrid powertrain control module, inspecting the powertrain CAN bus for faults, and using a scan tool to retrieve specific error codes for further troubleshooting.

4. Can I drive my vehicle with the U1817 code?

It is not recommended to drive your vehicle with the U1817 code present, as it can lead to further damage to the hybrid powertrain system and potentially unsafe driving conditions. It's best to have the issue diagnosed and repaired promptly.

5. How can I repair the U1817 code?

Repairing the U1817 code may involve repairing or replacing damaged wiring, addressing any issues with the powertrain control modules, resetting the system, and clearing the error code. It's advisable to seek assistance from a professional mechanic for proper diagnosis and repair.

6. Are there any DIY tips for fixing the U1817 code?

While some basic inspections like checking the wiring and connectors can be done by DIY enthusiasts, diagnosing and repairing the U1817 code may require specialized tools and expertise. It's recommended to consult a qualified mechanic for accurate diagnosis and repair.

7. Is the U1817 code specific to hybrid vehicles?

Yes, the U1817 code specifically relates to communication issues with the hybrid powertrain control module on Powertrain Expansion CAN Bus, which is commonly found in hybrid vehicles.

8. Can the U1817 code be intermittent?

Yes, the U1817 code can be intermittent, meaning the communication issue may come and go. It's important to address the problem even if it temporarily resolves, as it can reoccur and potentially cause more significant issues.

9. How much does it cost to repair the U1817 code?

The cost of repairing the U1817 code can vary depending on the underlying cause of the issue, the extent of the repairs needed, and the labor rates in your area. It's best to get a diagnosis from a mechanic to determine the exact cost.

10. If the U1817 code is cleared, will it come back?

If the underlying issue causing the U1817 code is not properly addressed and repaired, it is likely to return. Clearing the code without fixing the root cause will only temporarily mask the problem.