AutoCodes – Chevrolet – U18AA Chevrolet

U18AA Chevrolet Code - Transmission Range Control Module Lost Communication With Engine Control Module

Quick Answer

Devices connected to the serial data circuits monitor for serial data communications during normal vehicle operation. Common causes include Faulty Engine Control Module (ECM), Engine Control Module harness is open or shorted, Engine 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: U18AA Chevrolet indicates Transmission Range Control Module Lost Communication With Engine Control Module.
Common causes: Common causes include Faulty Engine Control Module (ECM), Engine Control Module harness is open or shorted, Engine 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 590

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 U18AA Chevrolet 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 U18AA Chevrolet - Transmission Range Control Module Lost Communication With Engine Control Module - AutoCodes.com — U18AA Chevrolet Code - Transmission Range Control Module Lost Communication With Engine Control Module

What does this mean?

What are the Possible Causes of the DTC U18AA Chevrolet?

Faulty Engine Control Module (ECM)
Engine Control Module harness is open or shorted
Engine Control Module circuit poor electrical connection

How to Fix the DTC U18AA Chevrolet?

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 U18AA Chevrolet 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 U18AA Chevrolet Code

1. What are the common symptoms of OBDII code U18AA in a Chevrolet related to the Transmission Range Control Module?

- Common symptoms include issues with shifting gears, transmission slipping, hesitation during acceleration, and the transmission going into limp mode.

2. What can cause the Transmission Range Control Module to lose communication with the Engine Control Module in a Chevrolet?

- Possible causes include wiring harness issues, loose or corroded connections, a faulty transmission range control module, or a problem with the engine control module.

3. How can I diagnose the U18AA trouble code in a Chevrolet related to the Transmission Range Control Module?

- Diagnosing this code usually involves performing a thorough inspection of the wiring, connectors, and modules involved, as well as using a diagnostic scan tool to retrieve specific fault codes.

4. Is it safe to continue driving my Chevrolet with the U18AA code related to the Transmission Range Control Module?

- It is not recommended to continue driving the vehicle when this code is present, as it can lead to drivability issues and potential safety hazards.

5. What repairs are typically needed to fix the U18AA code in a Chevrolet related to the Transmission Range Control Module?

- Repairs may involve repairing or replacing damaged wiring, repairing connectors, replacing the transmission range control module, or addressing any underlying issues with the engine control module.

6. Can a DIY enthusiast fix the U18AA trouble code in a Chevrolet related to the Transmission Range Control Module?

- While some basic troubleshooting steps can be taken by enthusiasts, diagnosing and repairing this code often requires specialized tools and knowledge best left to professional technicians.

7. How much does it cost to repair the U18AA code in a Chevrolet related to the Transmission Range Control Module?

- The cost of repair can vary depending on the exact cause of the issue and the labor rates in your area, but it is advisable to budget for diagnostic fees, parts replacement, and labor costs.

8. Will resetting the trouble codes make the U18AA code related to the Transmission Range Control Module go away in a Chevrolet?

- Resetting the codes may temporarily clear the warning light, but if the underlying issue is not addressed, the code is likely to return once the system detects the problem again.

9. Can extreme weather conditions affect the occurrence of the U18AA code in a Chevrolet related to the Transmission Range Control Module?

- Extreme weather conditions, such as heat or cold, can sometimes exacerbate existing electrical issues and lead to communication errors between modules, potentially triggering the U18AA code.

10. Are there any recalls or service bulletins related to the U18AA code in Chevrolet vehicles with Transmission Range Control Module issues?

- It's advisable to check with a Chevrolet dealership or online databases to see if there are any recalls or service bulletins addressing the U18AA code specifically for your vehicle model and year.