AutoCodes – GMC – U18CC GMC

U18CC GMC 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 GMC 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 641

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 GMC 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 GMC - Transmission Range Control Module Lost Communication With ECM On Powertrain Expansion Bus - AutoCodes.com — U18CC GMC 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 GMC?

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 GMC?

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 GMC 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 U18CC GMC Code

1. What are the common symptoms of OBDII code U18CC GMC?

The common symptoms of code U18CC GMC include issues with shifting gears, engine stalling, poor acceleration, and the transmission getting stuck in a single gear.

2. What are the possible causes of code U18CC GMC?

The possible causes of code U18CC GMC include faulty transmission range control module, communication issues between the transmission module and engine control module, damaged wiring or connectors, and software glitches.

3. How can I diagnose code U18CC GMC?

Diagnosing code U18CC GMC typically involves using a professional OBDII scanner to retrieve the trouble codes, performing a thorough inspection of the wiring and connectors, and testing the communication between the transmission range control module and the engine control module.

4. Can I still drive my vehicle with code U18CC GMC?

It is not recommended to drive your vehicle with code U18CC GMC as it can lead to further damage to the transmission system and potentially cause safety hazards on the road.

5. How can I repair OBDII code U18CC GMC?

Repairing code U18CC GMC may involve replacing the transmission range control module, repairing or replacing damaged wiring and connectors, updating the software, and ensuring proper communication between the modules.

6. Is it safe to reset the trouble codes related to U18CC GMC without fixing the underlying issue?

Resetting the trouble codes without fixing the underlying issue is not recommended as the problem will likely persist, leading to potential safety risks and further damage to the vehicle's transmission system.

7. How much does it cost to repair code U18CC GMC?

The cost of repairing code U18CC GMC can vary depending on the specific issue, the labor rates of the repair shop, and the cost of replacement parts. It is advisable to get a diagnostic from a professional technician to determine the exact repair cost.

8. Can a DIY enthusiast fix code U18CC GMC at home?

While some simple repairs like checking and cleaning connectors or replacing fuses can be done at home, diagnosing and repairing complex issues related to code U18CC GMC may require specialized tools and expertise best handled by a professional mechanic.

9. How long does it take to repair code U18CC GMC?

The repair time for code U18CC GMC can vary depending on the specific issue, availability of parts, and the workload of the repair shop. It is recommended to consult with a technician for a more accurate estimate of the repair duration.

10. Are there any preventive measures to avoid code U18CC GMC in the future?

Regular maintenance, such as checking and cleaning connectors, ensuring proper wiring integrity, and updating software as recommended by the manufacturer, can help prevent code U18CC GMC from occurring in the future.