AutoCodes – Generic – U1891

U1891 Code - Hybrid Control Module Lost Communication With Instrument Panel Cluster

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 Instrument Panel Cluster (IPC), Instrument Panel Cluster harness is open or shorted, Instrument Panel Cluster 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: U1891 indicates Hybrid Control Module Lost Communication With Instrument Panel Cluster.
Common causes: Common causes include Faulty Instrument Panel Cluster (IPC), Instrument Panel Cluster harness is open or shorted, Instrument Panel Cluster 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 681

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 U1891 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 U1891 - Hybrid Control Module Lost Communication With Instrument Panel Cluster - AutoCodes.com — U1891 Code - Hybrid Control Module Lost Communication With Instrument Panel Cluster

What does this mean?

What are the Possible Causes of the DTC U1891?

Faulty Instrument Panel Cluster (IPC)
Instrument Panel Cluster harness is open or shorted
Instrument Panel Cluster circuit poor electrical connection
Faulty Hybrid Control Module (HCM)

How to Fix the DTC U1891?

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 U1891 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 U1891 code?

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Information for Specific Makes

U1891 Buick — Hybrid Control Module Lost Communication With Instrument Panel Cluster
U1891 Cadillac — Hybrid Control Module Lost Communication With Instrument Panel Cluster
U1891 Chevrolet — Hybrid Control Module Lost Communication With Instrument Panel Cluster
U1891 GMC — Hybrid Control Module Lost Communication With Instrument Panel Cluster

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 U1891 Code

1. What does the OBDII code U1891 mean?

U1891 indicates that the Hybrid Control Module has lost communication with the Instrument Panel Cluster, which could affect hybrid system monitoring and display functions.

2. What are the common symptoms of code U1891?

Symptoms might include a malfunctioning or blank instrument cluster, warning lights on the dashboard, or erratic hybrid system behavior.

3. What causes the U1891 code to appear?

Common causes include damaged wiring, loose or corroded electrical connections, a faulty Instrument Panel Cluster, or a malfunctioning Hybrid Control Module.

4. Can U1891 cause drivability issues?

While it may not directly affect how the vehicle drives, it could interfere with important hybrid system monitoring and warnings, potentially leading to safety concerns.

5. How do you diagnose the U1891 code?

Diagnosis involves inspecting the wiring and connectors between the Hybrid Control Module and Instrument Panel Cluster, testing for continuity, and scanning for additional related trouble codes.

6. Can a dead battery trigger the U1891 code?

Yes, a weak or failing 12V battery can disrupt communication between modules, potentially triggering the U1891 code.

7. How is the U1891 code fixed?

Repairs may include repairing or replacing damaged wiring, cleaning corroded connectors, reprogramming or updating the modules, or replacing a faulty Hybrid Control Module or Instrument Cluster.

8. How much does it cost to fix the U1891 code?

Repair costs can vary widely depending on the root cause, ranging from $100 for simple wiring repairs to over $1,000 if a module or cluster needs replacement.

9. Can I drive with the U1891 code?

While the car might remain drivable, it is not recommended as the hybrid system monitoring could be compromised, leading to potential safety risks.

10. Is U1891 a common issue in hybrid vehicles?

It is not highly common but can occur, particularly in aging hybrid vehicles or those with electrical system issues. Regular maintenance can help prevent such problems.