U18AB GMC Code - Transmission Range Control Module Lost Communication With Chassis Control Module On High Speed CAN Bus
Quick Answer
The U18AB GMC code indicates that the Transmission Range Control Module (TRCM) has lost communication with the Chassis Control Module (CCM) on the High-Speed Controller Area Network (CAN) bus. Common causes include Damaged wiring or connectors in the CAN bus network, Faulty Transmission Range Control Module (TRCM), Faulty Chassis Control Module (CCM). 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
- U18AB GMC indicates Transmission Range Control Module Lost Communication With Chassis Control Module On High Speed CAN Bus.
- Common causes
- Common causes include Damaged wiring or connectors in the CAN bus network, Faulty Transmission Range Control Module (TRCM), Faulty Chassis Control Module (CCM).
- 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.
Fix Your Car Smarter
Try the New AutoCodes App!
Get complete OBDII diagnostics, repair solutions, and cost estimates, plus AI chat support on demand.
Code U18AB GMC Description
The U18AB GMC code indicates that the Transmission Range Control Module (TRCM) has lost communication with the Chassis Control Module (CCM) on the High-Speed Controller Area Network (CAN) bus. The TRCM is responsible for controlling the transmission's shifting patterns and ensuring smooth operation, while the CCM manages various chassis-related functions such as stability control and traction control. When these modules fail to communicate, it can lead to a range of issues affecting the vehicle's performance and safety.
Common Causes of U18AB GMC
- Damaged wiring or connectors in the CAN bus network
- Faulty Transmission Range Control Module (TRCM)
- Faulty Chassis Control Module (CCM)
- Software issues or programming errors
- Corrosion or moisture damage in the module connectors
Symptoms of U18AB GMC
- Erratic shifting behavior
- Transmission slippage
- Harsh engagements
- Dashboard warning lights (Check Engine Light, Transmission Warning Light)
- Limp mode activation
How to Fix U18AB GMC
- Perform a thorough diagnostic scan to retrieve the fault codes and pinpoint the communication issue between the TRCM and CCM.
- Inspect the wiring harness, connectors, and modules for any visible damage or corrosion. Repair or replace as necessary.
- Test the TRCM and CCM modules for proper functionality. Replace any faulty modules.
- Clear the fault codes and reset the system to ensure proper communication between the modules.
- Test drive the vehicle to verify that the transmission operates smoothly and that the warning lights are no longer illuminated.
Cost to Fix U18AB GMC
The typical repair costs for addressing the U18AB GMC code can range from $200 to $500, depending on the extent of the issue and the cost of parts and labor. It's important to note that specific diagnosis time and labor rates at auto repair shops can vary based on factors such as location, vehicle make and model, and engine type. Auto repair shops commonly charge between $80 and $150 per hour for labor, but rates may be higher in metropolitan areas or at dealerships, while independent shops may charge less. It's advisable to check local rates for a more accurate estimate.
Need more information about the U18AB GMC code?
Need more information on how to fix the U18AB GMC code? Get Access to Factory Service Manuals
Need Help with the Code?
Get the U18AB GMC code diagnosed by a professional: Find a repair shop in your area
Frequently Asked Questions about U18AB GMC Code
1. What are the common symptoms of OBDII code U18AB in a GMC vehicle?
The common symptoms include transmission shifting issues, the transmission stuck in one gear, illumination of the Check Engine Light, and potential loss of communication with other control modules.
2. What does the OBDII code U18AB GMC indicate?
This code indicates that the Transmission Range Control Module has lost communication with the Chassis Control Module on the High-Speed CAN Bus network.
3. What are some possible causes of the U18AB code in a GMC vehicle?
Possible causes include a faulty Transmission Range Control Module, issues with the Chassis Control Module, damaged wiring or connectors in the CAN Bus network, or a communication error between modules.
4. How can I diagnose the U18AB code in my GMC vehicle?
Diagnosing this code typically involves using a professional OBDII scanner to retrieve the code, checking for other related codes, inspecting the wiring and connectors in the CAN Bus network, and testing the communication between modules.
5. Can I still drive my GMC vehicle with the U18AB code present?
It is not recommended to drive the vehicle with the U18AB code present, as it can lead to potential transmission issues and affect the overall performance and safety of the vehicle.
6. How is the U18AB code typically repaired in a GMC vehicle?
Repairing this code usually involves addressing the root cause of the communication error, such as replacing the faulty module, repairing damaged wiring or connectors, or reprogramming the control modules as needed.
7. Is it possible to reset the U18AB code without fixing the underlying issue?
Resetting the code without addressing the underlying issue may temporarily turn off the Check Engine Light, but the problem will likely reoccur until the root cause is properly repaired.
8. Can a DIY enthusiast fix the U18AB code in a GMC vehicle?
While basic troubleshooting like checking for loose connections or damaged wires can be done by a DIY enthusiast, diagnosing and repairing the specific cause of the U18AB code may require professional tools and expertise.
9. How long does it typically take to repair the U18AB code in a GMC vehicle?
The repair time can vary depending on the exact cause of the code and the complexity of the repair needed. It is best to consult with a mechanic for a more accurate estimate of the repair time.
10. How can I prevent the U18AB code from occurring in the future?
Regular maintenance checks, ensuring proper wiring connections, and addressing any communication issues between control modules promptly can help prevent the recurrence of the U18AB code in your GMC vehicle.
Discuss the causes and fixes for U18AB GMC OBDII Code
Code U18AB GMC comments
No comments found for this page.
Fix Your Car Smarter
Try the New AutoCodes App!
Get complete OBDII diagnostics, repair solutions, and cost estimates, plus AI chat support on demand.