AutoCodes – Chevrolet – U1890 Chevrolet

U1890 Chevrolet Code - Hybrid Control Module Lost Communication With HVAC 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 Heating, Ventilation, and Air Conditioning (HVAC) Control Module, HVAC Control Module harness is open or shorted, HVAC 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: U1890 Chevrolet indicates Hybrid Control Module Lost Communication With HVAC Control Module.
Common causes: Common causes include Faulty Heating, Ventilation, and Air Conditioning (HVAC) Control Module, HVAC Control Module harness is open or shorted, HVAC 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 646

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 U1890 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 U1890 Chevrolet - Hybrid Control Module Lost Communication With HVAC Control Module - AutoCodes.com — U1890 Chevrolet Code - Hybrid Control Module Lost Communication With HVAC Control Module

What does this mean?

What are the Possible Causes of the DTC U1890 Chevrolet?

Faulty Heating, Ventilation, and Air Conditioning (HVAC) Control Module
HVAC Control Module harness is open or shorted
HVAC Control Module circuit poor electrical connection
Faulty Hybrid Control Module (HCM)

How to Fix the DTC U1890 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 U1890 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 U1890 Chevrolet Code

1. What does the OBDII code U1890 mean on a Chevrolet?

U1890 indicates that the Hybrid Control Module has lost communication with the HVAC Control Module.

2. What are the common symptoms of the U1890 code in a Chevrolet?

Symptoms may include the HVAC system not functioning properly, reduced hybrid system performance, or warning lights on the dashboard.

3. What causes the U1890 code to appear on a Chevrolet?

Common causes include faulty wiring, a malfunctioning HVAC Control Module, Hybrid Control Module issues, or communication bus faults.

4. How can I diagnose the U1890 code on my Chevrolet?

Start by checking for damaged wiring or loose connections between the Hybrid Control Module and HVAC Control Module. Use a scan tool to confirm communication loss on the CAN bus.

5. Can a bad HVAC Control Module trigger the U1890 code?

Yes, a faulty HVAC Control Module can disrupt communication with the Hybrid Control Module and trigger the U1890 code.

6. Is the U1890 code specific to hybrid Chevrolet vehicles?

Yes, this code is specific to Chevrolet vehicles with hybrid systems, as it involves the Hybrid Control Module.

7. Can a blown fuse cause the U1890 code to appear?

Yes, a blown fuse related to the HVAC or Hybrid Control Module can interrupt communication and trigger the code.

8. How do I fix the U1890 code on my Chevrolet?

Repairs may involve fixing damaged wiring, replacing a faulty HVAC Control Module, or reprogramming the modules if necessary.

9. Can I drive my Chevrolet with the U1890 code active?

While you might still be able to drive, it's not recommended as it could affect hybrid system performance and HVAC operation.

10. How much does it cost to fix the U1890 code on a Chevrolet?

Repair costs vary but may include diagnostic fees, wiring repairs, or module replacements, typically ranging from $100 to $1,000 depending on the issue.