AutoCodes – Generic – U18CC

U18CC Code - Transmission Range Control Module Lost Communication With ECM On Powertrain Expansion Bus

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: U18CC indicates Transmission Range Control Module Lost Communication With ECM On Powertrain Expansion Bus.
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 660

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 09, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code U18CC 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 U18CC - Transmission Range Control Module Lost Communication With ECM On Powertrain Expansion Bus - AutoCodes.com — U18CC Code - Transmission Range Control Module Lost Communication With ECM On Powertrain Expansion Bus

What does this mean?

What are the Possible Causes of the DTC U18CC?

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 U18CC?

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 U18CC 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 U18CC code?

Need more information on how to fix the U18CC code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the U18CC code diagnosed by a professional: Find a repair shop in your area

Information for Specific Makes

U18CC Buick — Transmission Range Control Module Lost Communication With ECM On Powertrain Expansion Bus
U18CC Cadillac — Transmission Range Control Module Lost Communication With ECM On Powertrain Expansion Bus
U18CC Chevrolet — Transmission Range Control Module Lost Communication With ECM On Powertrain Expansion Bus
U18CC GMC — Transmission Range Control Module Lost Communication With ECM On Powertrain Expansion 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 U18CC Code

What does the OBDII code U18CC indicate?

The OBDII code U18CC indicates that there is a lost communication issue between the Transmission Range Control Module and the Engine Control Module on the Powertrain Expansion Bus.

What are the common symptoms of the U18CC code?

Common symptoms include transmission shifting issues, erratic behavior of the transmission, warning lights on the dashboard, and potentially poor engine performance.

What are the possible causes of the U18CC code?

Possible causes include faulty wiring or connectors, a malfunctioning Transmission Range Control Module, issues with the Engine Control Module, or problems with the Powertrain Expansion Bus itself.

How can I diagnose a U18CC code?

To diagnose a U18CC code, check the vehicle's wiring and connectors for damage or corrosion, use a scan tool to check for related codes, and verify communication between the Transmission Range Control Module and Engine Control Module.

What repairs can be performed to fix the U18CC code?

Repairs may include repairing or replacing damaged wiring or connectors, replacing a faulty Transmission Range Control Module, updating or replacing the Engine Control Module, or addressing any issues with the Powertrain Expansion Bus.

Can I drive my vehicle with the U18CC code?

While it may be possible to drive the vehicle, doing so can cause transmission issues and could lead to further damage. It is advisable to address the code as soon as possible.

Is it necessary to reset the check engine light after fixing the U18CC code?

Yes, after repairs are made, it is recommended to clear the code and reset the check engine light using an OBDII scanner to ensure the issue has been resolved.

How much does it typically cost to repair the U18CC code?

Repair costs can vary widely, ranging from $100 to over $1,000 depending on the underlying issue, parts required, and labor costs. It's best to get a detailed estimate from a qualified mechanic.

Can a faulty battery cause the U18CC code?

Yes, a weak or failing battery can lead to communication issues between modules, potentially triggering the U18CC code. It's important to ensure the battery and charging system are in good condition.

Are there any specific vehicle makes or models prone to the U18CC code?

Certain makes and models may experience this code more frequently due to design and manufacturing quirks, but it can occur in any vehicle equipped with OBDII systems. Always consult manufacturer-specific forums or resources for more targeted information.