U1026 2017 GMC Sierra 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 2017 GMC Sierra 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.
Code U1026 2017 GMC Sierra Description
What are the Possible Causes of the DTC U1026 2017 GMC Sierra?
- 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 2017 GMC Sierra?
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.
Code Tech Notes
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 2017 GMC Sierra 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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Frequently Asked Questions about U1026 2017 GMC Sierra Code
1. What does the OBDII code U1026 mean on a 2017 GMC Sierra?
The U1026 code indicates lost communication with the Transfer Case Control Module (TCCM), meaning the module is not responding or communicating with other vehicle systems.
2. What are the common symptoms of the U1026 code on a 2017 GMC Sierra?
Symptoms may include the 4WD system not engaging, the service 4WD light illuminating, erratic shifting, or no response when selecting 4WD modes.
3. What causes the U1026 code to appear?
Common causes include a faulty Transfer Case Control Module, damaged or corroded wiring or connectors, a blown fuse, or a malfunction in the CAN (Controller Area Network).
4. Can a dead battery trigger the U1026 code on a 2017 GMC Sierra?
Yes, a weak or dead battery can disrupt communication between modules, potentially triggering the U1026 code.
5. How do you diagnose the U1026 code on a 2017 GMC Sierra?
Diagnosis involves checking for other related codes, inspecting the TCCM wiring and connections, testing the CAN network, and verifying the TCCM power supply and ground.
6. Can you drive a 2017 GMC Sierra with the U1026 code?
While it’s possible to drive, the 4WD system may not function properly, which could be risky in certain driving conditions. It’s best to address the issue promptly.
7. How do you fix the U1026 code on a 2017 GMC Sierra?
Repairs may include replacing or repairing damaged wires, cleaning corroded connectors, updating or reprogramming the TCCM, or replacing the faulty module if necessary.
8. Is the U1026 code specific to the 2017 GMC Sierra?
No, the U1026 code is a generic communication code and can appear on other vehicles with similar systems, but the specific symptoms and fixes may vary.
9. Does the U1026 code always mean the TCCM is faulty?
No, most U1026 issues are caused by wiring problems, poor connections, or power supply issues rather than a faulty TCCM itself.
10. How much does it cost to repair the U1026 code on a 2017 GMC Sierra?
Repair costs can vary widely, ranging from $50-$150 for minor wiring repairs to $300-$700 or more if the TCCM needs replacement.
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