AutoCodes – Buick – U18AC Buick

U18AC Buick Code - Transmission Range Control Module Lost Communication With Chassis 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 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: U18AC Buick indicates Transmission Range Control Module Lost Communication With Chassis Control Module On Chassis Expansion 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 638

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 U18AC Buick 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 U18AC Buick - Transmission Range Control Module Lost Communication With Chassis Control Module On Chassis Expansion CAN Bus - AutoCodes.com — U18AC Buick Code - Transmission Range Control Module Lost Communication With Chassis Control Module On Chassis Expansion CAN Bus

What does this mean?

What are the Possible Causes of the DTC U18AC Buick?

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

How to Fix the DTC U18AC Buick?

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 U18AC Buick 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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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 U18AC Buick Code

1. What are the common symptoms of OBDII code U18AC in a Buick related to transmission range control module lost communication with chassis control module?

- Common symptoms include transmission shifting issues, check engine light illuminated, and potential loss of communication with other vehicle modules.

2. What are the possible causes of OBDII code U18AC in a Buick?

- The code U18AC may be triggered by damaged wiring or connectors, a faulty transmission range control module, a malfunctioning chassis control module, or issues with the CAN bus communication system.

3. How can I diagnose the OBDII code U18AC in my Buick?

- Diagnosis typically involves using an OBDII scanner to read the code, checking for any related trouble codes, inspecting the wiring and connectors for damage, and testing the transmission range control module and chassis control module for functionality.

4. Can I drive my Buick with the U18AC code present?

- It is not recommended to drive the vehicle with the U18AC code active, as it can lead to transmission issues and potential safety concerns. It is best to address the problem promptly.

5. How can I repair the U18AC code in my Buick?

- Repair options may include repairing or replacing damaged wiring or connectors, replacing the transmission range control module or chassis control module if faulty, and ensuring proper communication on the CAN bus system.

6. Are there any DIY tips for addressing the U18AC code in my Buick?

- DIY tips may include visually inspecting wiring and connectors for damage, checking for loose connections, and ensuring all modules are securely connected. However, complex repairs may require professional assistance.

7. How much does it typically cost to repair the U18AC code in a Buick?

- The cost of repairing the U18AC code can vary depending on the specific cause of the issue, the extent of the repair needed, and labor rates. It is advisable to obtain quotes from reputable mechanics or dealerships.

8. Can the U18AC code be intermittent in a Buick?

- Yes, the U18AC code can be intermittent, meaning it may come and go based on certain conditions or communication failures between modules. It is important to address intermittent issues promptly to prevent further complications.

9. Will resetting the OBDII code U18AC make it go away permanently?

- Simply resetting the code may temporarily clear the check engine light, but it will not fix the underlying issue causing the U18AC code. It is crucial to diagnose and repair the problem to prevent future occurrences.

10. Is the U18AC code common in Buick vehicles?

- The U18AC code related to transmission range control module lost communication with chassis control module on the chassis expansion CAN bus is specific to certain Buick models and may not be as common as other OBDII codes.