AutoCodes – Generic – U1026

U1026 Code - Lost Communication with Transfer Case Control Module

Quick Answer

Devices connected to the serial data circuits monitor for serial data communications during normal vehicle operation. Common causes include Faulty Transfer Case Control Module, Transfer Case Control Module harness is open or shorted, Transfer Case 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: U1026 indicates Lost Communication with Transfer Case Control Module.
Common causes: Common causes include Faulty Transfer Case Control Module, Transfer Case Control Module harness is open or shorted, Transfer Case 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 45,288

How popular is this code, among other codes? Medium

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
Tech Notes
Cost to Diagnose
FAQs
Comments
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Code U1026 Description

Devices connected to the 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 Diagnostic Trouble Code (DTC) will be set when a supervised periodic message that includes the transmitter device availability has not been received.

OBDII Code U1026 - Lost Communication with Transfer Case Control Module - AutoCodes.com — U1026 Code - Lost Communication with Transfer Case Control Module

What does this mean?

What are the Possible Causes of the DTC U1026?

Faulty Transfer Case Control Module
Transfer Case Control Module harness is open or shorted
Transfer Case Control Module circuit poor electrical connection

How to Fix the DTC U1026?

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 does this mean?

Code Tech Notes

This is typically an electrical wiring connection issue at one of the controllers being monitored by the manufacturer.
It can occur if:
Someone changes a battery while the ignition switch is left on, that is, left in the Run position.
Someone flashes/upgrades their engine controller - other modules unable to communicate with PCM during this process - this will set U1026 at a multitude of controllers on the vehicle - all false codes. Erase and carry on.
May need to disconnect both battery cables and touch them together for 15 seconds. Reattach battery cables, positive first, then negative and see if a soft reset helps.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the U1026 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 U1026 code?

Need more information on how to fix the U1026 code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the U1026 code diagnosed by a professional: Find a repair shop in your area

Information for Specific Makes

U1026 Buick — Lost Communication with Transfer Case Control Module
U1026 Cadillac — Lost Communication with Transfer Case Control Module
U1026 Chevrolet — Lost Communication with Transfer Case Control Module
U1026 GMC — Lost Communication with Transfer Case Control Module

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 U1026 Code

1. What are the common symptoms of OBDII code U1026 (Lost Communication with Transfer Case Control Module)?

- Common symptoms include issues with the 4WD system, warning lights on the dashboard (such as the 4WD light), and difficulty shifting into 4WD.

2. What are some possible causes of OBDII code U1026?

- Possible causes include a faulty transfer case control module, damaged wiring or connectors, a blown fuse, or issues with the communication network.

3. How can I diagnose the cause of OBDII code U1026?

- Diagnosing this code typically involves using a professional OBDII scanner to retrieve the trouble codes, checking the wiring and connectors for any damage, and testing the transfer case control module.

4. Can a DIY enthusiast repair OBDII code U1026 at home?

- While some simple causes like blown fuses or loose connectors can be fixed at home, diagnosing and repairing advanced issues with the transfer case control module may require professional help.

5. Is it safe to continue driving with OBDII code U1026 present?

- It is generally not recommended to drive with this code present, as it can lead to further damage to the transfer case or 4WD system if left unresolved.

6. How much does it typically cost to repair OBDII code U1026?

- The cost of repairing this code can vary widely depending on the underlying cause, but it is advisable to budget for diagnostic fees, parts replacement costs, and labor charges.

7. Are there any preventive maintenance tips to avoid OBDII code U1026 in the future?

- Regularly inspecting and maintaining the transfer case control module, checking for loose connections, and addressing any warning lights promptly can help prevent this code from appearing.

8. Can extreme weather conditions contribute to triggering OBDII code U1026?

- Yes, extreme weather conditions like heavy rain, snow, or temperature changes can sometimes cause electrical issues that lead to communication failures with the transfer case control module.

9. How long does it usually take to repair OBDII code U1026?

- The repair time for this code can vary depending on the complexity of the issue and the availability of parts, but it is advisable to consult with a professional technician for a more accurate estimate.

10. Will resetting the OBDII code U1026 clear the issue permanently?

- Resetting the code may temporarily clear the warning lights, but if the underlying issue is not addressed, the code is likely to reappear. It is important to diagnose and repair the root cause of the problem.