AutoCodes – GMC – U18A2 2017 GMC Sierra

U18A2 2017 GMC Sierra Code - Lost Communication with Fuel Pump Driver Control Module

Quick Answer

Devices connected to the serial data circuits monitor for serial data communications during normal vehicle operation. Common causes include Faulty Fuel Pump Driver Control Module, Fuel Pump Driver Control Module harness is open or shorted, Fuel Pump Driver 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: U18A2 2017 GMC Sierra indicates Lost Communication with Fuel Pump Driver Control Module.
Common causes: Common causes include Faulty Fuel Pump Driver Control Module, Fuel Pump Driver Control Module harness is open or shorted, Fuel Pump Driver 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 529

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 Apr 14, 2023

Description
Possible Causes
How To Fix
Tech Notes
Cost to Diagnose
FAQs
Comments
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Code U18A2 2017 GMC Sierra 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 U18A2 2017 GMC Sierra - Lost Communication with Fuel Pump Driver Control Module - AutoCodes.com — U18A2 2017 GMC Sierra Code - Lost Communication with Fuel Pump Driver Control Module

What does this mean?

What are the Possible Causes of the DTC U18A2 2017 GMC Sierra?

Faulty Fuel Pump Driver Control Module
Fuel Pump Driver Control Module harness is open or shorted
Fuel Pump Driver Control Module circuit poor electrical connection

How to Fix the DTC U18A2 2017 GMC Sierra?

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 does this mean?

Code Tech Notes

There is a Factory Service Bulletin for the following Chevrolet Models:

- 2014-2018 Chevrolet Silverado
- 2015-2018 Chevrolet Suburban
- 2015-2018 Chevrolet Tahoe

If the Diagnostic Trouble Codes (DTC) P2635, U0074, and/or U18A2 are set, it may be found that the actual fuel pressure (low-pressure system) will be reading substantially higher than desired fuel pressure, in this case, the cause of the problem is a loss of communication between Engine Control Module (ECM) and Fuel Pump Control Module (FPCM).

- Diagnose for any communication DTCs set (U0074 would take priority over U18A2 if both set) before addressing DTC P2635.
- If DTC P2635 is not resolved by correcting the communication DTCs, only then should diagnose the DTC P2635.
- It has been found that a communication issue between the FPCM and ECM can potentially induce DTC P2635 and result in a pressure differential between actual and desired fuel system pressures.
- If the actual fuel pressure is substantially higher than desired (10 psi / 70 kPa or more), replacement of the fuel pump control module or fuel system components typically will not resolve this issue.
- If the actual fuel pressure is substantially lower than desired (10 psi / 70 kPa or more), this Factory Service Bulletin would NOT apply. It would be recommended to diagnose low actual fuel pressure.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the U18A2 2017 GMC Sierra 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 U18A2 2017 GMC Sierra code?

Need more information on how to fix the U18A2 2017 GMC Sierra code? Get Access to Factory Service Manuals

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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 U18A2 2017 GMC Sierra Code

1. What are common symptoms of OBDII code U18A2 in a 2017 GMC Sierra related to lost communication with the Fuel Pump Driver Control Module?

- Common symptoms include issues starting the vehicle, engine stalling, and fuel pump malfunctions.

2. What are possible causes of OBDII code U18A2 in a 2017 GMC Sierra indicating lost communication with the Fuel Pump Driver Control Module?

- Possible causes may include a faulty fuel pump driver control module, damaged wiring or connectors, or a communication network problem.

3. How can I diagnose the OBDII code U18A2 in a 2017 GMC Sierra to determine the exact cause of lost communication with the Fuel Pump Driver Control Module?

- Diagnosis typically involves using a scan tool to check for additional trouble codes, inspecting the wiring and connectors for damage, and testing the fuel pump driver control module.

4. Is it safe to continue driving a 2017 GMC Sierra with the OBDII code U18A2 indicating lost communication with the Fuel Pump Driver Control Module?

- It is not recommended to continue driving the vehicle as it may lead to potential fuel system issues and engine performance problems.

5. Can I reset the OBDII code U18A2 in a 2017 GMC Sierra related to lost communication with the Fuel Pump Driver Control Module without fixing the underlying issue?

- While you can clear the code temporarily, it is essential to address the root cause to prevent further complications and ensure the proper functioning of the fuel pump system.

6. Are there any DIY repair tips for resolving OBDII code U18A2 in a 2017 GMC Sierra due to lost communication with the Fuel Pump Driver Control Module?

- DIY repair tips may include checking and repairing any damaged wiring or connectors, ensuring proper grounds, and consulting the vehicle's service manual for specific troubleshooting steps.

7. How much does it typically cost to repair OBDII code U18A2 in a 2017 GMC Sierra associated with lost communication with the Fuel Pump Driver Control Module?

- The repair cost can vary depending on the exact cause of the issue, but it may involve replacing the fuel pump driver control module, repairing wiring, or addressing communication network problems.

8. Can extreme weather conditions or environmental factors trigger the OBDII code U18A2 in a 2017 GMC Sierra related to lost communication with the Fuel Pump Driver Control Module?

- Yes, extreme temperatures or moisture exposure can sometimes contribute to electrical issues leading to communication failures with the Fuel Pump Driver Control Module.

9. Is the OBDII code U18A2 specific to 2017 GMC Sierra models with regards to lost communication with the Fuel Pump Driver Control Module?

- While the specific code may vary between vehicle makes and models, the underlying issue of lost communication with the Fuel Pump Driver Control Module is a common problem in many vehicles.

10. How urgent is it to address the OBDII code U18A2 in a 2017 GMC Sierra indicating lost communication with the Fuel Pump Driver Control Module?

- It is recommended to address the issue promptly to prevent potential fuel system failures, engine performance issues, and further damage to the vehicle.