AutoCodes – Chevrolet – U1894 Chevrolet

U1894 Chevrolet Code - Hybrid Control Module Lost Communication With Starter/Generator Control Module

Quick Answer

Modules connected to the class 2 and 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 (SGCM), 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: U1894 Chevrolet indicates Hybrid Control Module Lost Communication With Starter/Generator Control Module.
Common causes: Common causes include Faulty Starter/Generator Control Module (SGCM), 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.

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Code Popularity 925

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

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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 U1894 Chevrolet Description

Modules connected to the class 2 and 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 modules. The Diagnostic Trouble Code (DTC) is reported on a class 2 link to the scan tool by Powertrain Control Module (PCM) even if they may be set by different modules. The DTC will set when a node alive message has not been received from an identified module within the last 5 seconds after establishing class 2 serial data communication, or a supervised high-speed GMLAN message has not been received.

OBDII Code U1894 Chevrolet - Hybrid Control Module Lost Communication With Starter/Generator Control Module - AutoCodes.com — U1894 Chevrolet Code - Hybrid Control Module Lost Communication With Starter/Generator Control Module

What does this mean?

What are the Possible Causes of the DTC U1894 Chevrolet?

Faulty Starter/Generator Control Module (SGCM)
Starter/Generator Control Module harness is open or shorted
Starter/Generator Control Module circuit poor electrical connection
Faulty Hybrid Control Module (HCM)

How to Fix the DTC U1894 Chevrolet?

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 U1894 Chevrolet 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 U1894 Chevrolet Code

1. What are the common symptoms of OBDII code U1894 in a Chevrolet vehicle?

- Common symptoms include issues with starting the vehicle, loss of power, and the hybrid system not functioning properly.

2. What can cause the Hybrid Control Module to lose communication with the Starter/Generator Control Module?

- Possible causes include wiring issues, a faulty control module, a loose connection, or a software glitch.

3. How can I diagnose the U1894 code in my Chevrolet with the hybrid system?

- A diagnostic scan tool can help identify the specific communication error between the control modules.

4. Can I still drive my Chevrolet if the U1894 code is present?

- It is not recommended to drive the vehicle with this code as it can affect the hybrid system's performance and potentially lead to further issues.

5. How can I repair the communication error between the Hybrid Control Module and Starter/Generator Control Module?

- Repair options include checking and fixing any wiring issues, ensuring connections are secure, updating software, or replacing faulty control modules.

6. Is it safe to clear the U1894 trouble code without addressing the underlying issue?

- Clearing the code without fixing the communication problem may temporarily remove the warning light, but the issue will likely reoccur and affect the vehicle's performance.

7. Can a DIY enthusiast fix the U1894 code in a Chevrolet or is professional assistance needed?

- Depending on the root cause, some DIY enthusiasts with experience in automotive repairs may be able to address the issue, but professional assistance is recommended for complex repairs.

8. How much does it typically cost to repair the U1894 code in a Chevrolet?

- The cost of repair can vary based on the specific cause of the communication error, with factors like parts and labor contributing to the overall cost.

9. Will resetting the vehicle's battery help resolve the U1894 trouble code?

- Resetting the battery may temporarily clear the code, but if the underlying issue causing the communication error persists, the code is likely to return.

10. How often does the U1894 code occur in Chevrolet vehicles with hybrid systems?

- While not extremely common, the U1894 code can occur in Chevrolet vehicles equipped with hybrid systems, especially in older models or due to electrical system issues.