AutoCodes – Generic – U18AB

U18AB Code - Transmission Range Control Module Lost Communication With Chassis Control Module On High Speed CAN Bus

Quick Answer

Devices connected to the serial data circuits monitor for serial data communications during normal vehicle operation. Common causes include Faulty Chassis Control Module, Chassis Control Module harness is open or shorted, Chassis 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: U18AB indicates Transmission Range Control Module Lost Communication With Chassis Control Module On High Speed CAN Bus.
Common causes: Common causes include Faulty Chassis Control Module, Chassis Control Module harness is open or shorted, Chassis 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 560

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 U18AB 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 set a supervised periodic message that includes the transmitter device availability that has not been received.

OBDII Code U18AB - Transmission Range Control Module Lost Communication With Chassis Control Module On High Speed CAN Bus - AutoCodes.com — U18AB Code - Transmission Range Control Module Lost Communication With Chassis Control Module On High Speed CAN Bus

What does this mean?

What are the Possible Causes of the DTC U18AB?

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

How to Fix the DTC U18AB?

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 U18AB 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 U18AB code?

Need more information on how to fix the U18AB code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the U18AB code diagnosed by a professional: Find a repair shop in your area

Information for Specific Makes

U18AB Buick — Transmission Range Control Module Lost Communication With Chassis Control Module On High Speed CAN Bus
U18AB Cadillac — Transmission Range Control Module Lost Communication With Chassis Control Module On High Speed CAN Bus
U18AB Chevrolet — Transmission Range Control Module Lost Communication With Chassis Control Module On High Speed CAN Bus
U18AB GMC — Transmission Range Control Module Lost Communication With Chassis Control Module On High Speed CAN Bus

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 U18AB Code

1. What are the common symptoms of OBDII code U18AB?

- Common symptoms include transmission shifting issues, warning lights on the dashboard, and potential loss of communication between the transmission range control module and chassis control module.

2. What can cause the OBDII code U18AB to appear?

- The code U18AB usually appears when there is a communication problem between the transmission range control module and the chassis control module on the high-speed CAN bus.

3. How can I diagnose the OBDII code U18AB?

- Diagnosis typically involves using a professional OBDII scanner to retrieve the specific fault codes and checking the communication signals between the transmission range control module and chassis control module.

4. How serious is the U18AB code?

- The U18AB code is a serious issue as it can lead to potential transmission problems and affect the overall performance and safety of the vehicle.

5. Can I still drive my vehicle with the U18AB code present?

- It is not recommended to continue driving the vehicle with the U18AB code present, as it can lead to further damage to the transmission system and potentially compromise safety.

6. How can I repair the U18AB code?

- Repairing the U18AB code involves addressing the communication issue between the transmission range control module and chassis control module, which may require checking the wiring, connectors, and modules for any faults.

7. Can a DIY enthusiast fix the U18AB code?

- While some basic troubleshooting steps can be performed by a DIY enthusiast, resolving the U18AB code may require advanced diagnostic tools and expertise, so it is recommended to seek professional help.

8. Are there any common fixes for the U18AB code?

- Common fixes for the U18AB code may include repairing or replacing damaged wiring, connectors, or modules, reprogramming control modules, or updating software to restore proper communication.

9. How much does it cost to repair the U18AB code?

- The cost of repairing the U18AB code can vary depending on the extent of the issue, parts needed for replacement, and labor costs, so it is advisable to get a diagnosis from a professional technician.

10. Can the U18AB code be prevented?

- Regular maintenance, checking for loose connections, and addressing any transmission-related issues promptly can help prevent the occurrence of the U18AB code.