AutoCodes – Generic – U18A9

U18A9 Code - Lost Communication With Transmission Range Control Module On Chassis Expansion CAN Bus

Quick Answer

Devices connected to the serial data circuits monitor for serial data communications during normal vehicle operation. Common causes include Faulty Transmission Range Control Module, Transmission Range Control Module harness is open or shorted, Transmission Range 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: U18A9 indicates Lost Communication With Transmission Range Control Module On Chassis Expansion CAN Bus.
Common causes: Common causes include Faulty Transmission Range Control Module, Transmission Range Control Module harness is open or shorted, Transmission Range 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 758

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 U18A9 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 U18A9 - Lost Communication With Transmission Range Control Module On Chassis Expansion CAN Bus - AutoCodes.com — U18A9 Code - Lost Communication With Transmission Range Control Module On Chassis Expansion CAN Bus

What does this mean?

What are the Possible Causes of the DTC U18A9?

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

How to Fix the DTC U18A9?

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 U18A9 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 U18A9 code?

Need more information on how to fix the U18A9 code? Get Access to Factory Service Manuals

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Information for Specific Makes

U18A9 Buick — Lost Communication With Transmission Range Control Module On Chassis Expansion CAN Bus
U18A9 Cadillac — Lost Communication With Transmission Range Control Module On Chassis Expansion CAN Bus
U18A9 Chevrolet — Lost Communication With Transmission Range Control Module On Chassis Expansion CAN Bus
U18A9 GMC — Lost Communication With Transmission Range Control Module On Chassis Expansion 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 U18A9 Code

1. What are the common symptoms of OBDII code U18A9?

The common symptoms of OBDII code U18A9 include issues with shifting gears, transmission slipping, loss of power, and the vehicle going into limp mode.

2. What can cause the OBDII code U18A9 to appear?

The OBDII code U18A9, indicating Lost Communication With Transmission Range Control Module On Chassis Expansion CAN Bus, can be caused by a faulty transmission range control module, damaged wiring or connectors, or issues with the CAN bus communication system.

3. How can I diagnose the OBDII code U18A9?

Diagnosing the OBDII code U18A9 involves using a scan tool to retrieve the code, checking for any other related trouble codes, inspecting the wiring and connectors for damage, and testing the transmission range control module for proper functionality.

4. What are some repair tips for fixing the OBDII code U18A9?

Repair tips for fixing the OBDII code U18A9 may include repairing or replacing damaged wiring and connectors, replacing the faulty transmission range control module, and ensuring proper communication on the CAN bus system.

5. Can I drive my vehicle with the OBDII code U18A9?

It is not recommended to drive your vehicle with the OBDII code U18A9 present, as it can lead to further damage to the transmission system and potentially unsafe driving conditions.

6. How much does it typically cost to repair the OBDII code U18A9?

The cost of repairing the OBDII code U18A9 can vary depending on the underlying cause of the issue, but it may range from a few hundred to over a thousand dollars, including parts and labor.

7. Can a DIY enthusiast fix the OBDII code U18A9 at home?

While some DIY enthusiasts may have the skills to diagnose and repair the OBDII code U18A9, it is recommended to consult a professional mechanic or technician due to the complexity of transmission and communication system repairs.

8. How urgent is it to address the OBDII code U18A9?

It is important to address the OBDII code U18A9 promptly to prevent further damage to the transmission system and ensure the safe operation of your vehicle.

9. Is the OBDII code U18A9 a common issue in certain vehicle makes and models?

The OBDII code U18A9 may be more common in certain vehicle makes and models known for transmission or communication system issues, but it can occur in any vehicle with similar components.

10. How can I prevent the OBDII code U18A9 from recurring in the future?

To prevent the OBDII code U18A9 from recurring in the future, it is essential to perform regular maintenance on your vehicle, address any transmission or communication system issues promptly, and ensure proper wiring and connector integrity.