U0074 2018 GMC Sierra Code - Control Module Communication Powertrain Expansion CAN Bus Off Malfunction
Quick Answer
The U0074 diagnostic trouble code (DTC) for a 2018 GMC Sierra indicates a Control Module Communication Powertrain Expansion CAN Bus Off Malfunction. Common causes include Faulty Control Module: A malfunctioning control module can disrupt communication on the CAN bus, Wiring Issues: Damaged or corroded wiring connecting the control modules can cause communication errors, Software Glitch: A software bug or issue in the control modules' programming can lead to communication problems. 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
- U0074 2018 GMC Sierra indicates Control Module Communication Powertrain Expansion CAN Bus Off Malfunction.
- Common causes
- Common causes include Faulty Control Module: A malfunctioning control module can disrupt communication on the CAN bus, Wiring Issues: Damaged or corroded wiring connecting the control modules can cause communication errors, Software Glitch: A software bug or issue in the control modules' programming can lead to communication problems.
- 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 U0074 2018 GMC Sierra Description
The U0074 diagnostic trouble code (DTC) for a 2018 GMC Sierra indicates a Control Module Communication Powertrain Expansion CAN Bus Off Malfunction. This means that there is an issue with the communication system between various control modules in the vehicle related to the powertrain. The CAN (Controller Area Network) bus is a network that allows different modules in the vehicle to communicate with each other. When this communication is disrupted or disabled, it can lead to various performance issues and potential long-term effects if not addressed promptly.
Common Causes of U0074 2018 GMC Sierra
- Faulty Control Module: A malfunctioning control module can disrupt communication on the CAN bus.
- Wiring Issues: Damaged or corroded wiring connecting the control modules can cause communication errors.
- Software Glitch: A software bug or issue in the control modules' programming can lead to communication problems.
- Electrical Problems: Issues with the vehicle's electrical system, such as a weak battery or alternator, can affect communication between modules.
Symptoms of U0074 2018 GMC Sierra
- Check Engine Light: The most common symptom associated with this code is the illumination of the check engine light on the dashboard.
- Loss of Power: The vehicle may experience a loss of power or reduced performance while driving.
- Poor Fuel Economy: The engine may not be operating efficiently, leading to decreased fuel economy.
- Transmission Issues: Problems with shifting gears or erratic transmission behavior can occur.
- Rough Idling: The engine may idle roughly or inconsistently.
How to Fix U0074 2018 GMC Sierra
- Diagnose the Issue: Use a diagnostic scanner to retrieve the specific codes and pinpoint the source of the communication problem.
- Check Wiring and Connections: Inspect the wiring harnesses and connectors for any damage or corrosion, repairing or replacing as needed.
- Update Software: If a software glitch is suspected, updating the control modules' software may resolve the issue.
- Test Control Modules: Test the control modules to ensure they are functioning properly and communicating effectively.
- Clear Codes and Reset: After making any repairs, clear the codes and reset the system to see if the issue has been resolved.
Cost to Fix U0074 2018 GMC Sierra
The cost of repairing a U0074 code on a 2018 GMC Sierra can vary depending on the specific issue causing the communication malfunction. On average, the repair costs can range from $200 to $500, including parts and labor. However, it's important to note that diagnosis time and labor rates at auto repair shops can vary, so it's recommended to get estimates from local shops for a more accurate cost assessment.
Tech Notes for U0074 2018 GMC Sierra
- 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.
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Frequently Asked Questions about U0074 2018 GMC Sierra Code
1. What does the OBDII code U0074 mean on a 2018 GMC Sierra?
The U0074 code indicates a "Control Module Communication Powertrain Expansion CAN Bus Off Malfunction," meaning there is an issue with the vehicle's communication network.
2. What are common symptoms of code U0074 on the 2018 GMC Sierra?
Symptoms may include the check engine light turning on, erratic transmission behavior, loss of communication with certain control modules, or the vehicle failing to start.
3. What causes the U0074 code on a 2018 GMC Sierra?
Common causes include damaged or shorted wiring in the CAN bus system, a faulty control module, loose connections, or a malfunctioning CAN bus communication line.
4. Can a weak battery cause the U0074 code on a 2018 GMC Sierra?
Yes, a weak or failing battery can cause voltage issues, potentially leading to communication errors like the U0074 code.
5. How do you diagnose the U0074 code on a 2018 GMC Sierra?
Diagnosis involves using a scan tool to check for additional codes, inspecting wiring and connectors in the CAN bus system, and testing control module power and ground connections.
6. Is the U0074 code serious on a 2018 GMC Sierra?
Yes, it can be serious as it impacts communication between critical modules, possibly leading to drivability issues or a complete loss of vehicle function.
7. How do you fix code U0074 on a 2018 GMC Sierra?
Repairs may include fixing or replacing damaged wiring, reconnecting loose connectors, replacing a faulty control module, or resetting the system after repairs.
8. Can driving with the U0074 code cause further damage to my GMC Sierra?
Yes, ignoring the code could lead to further electrical or module damage, as well as potential safety issues if the problem disrupts critical systems.
9. What tools are needed to troubleshoot the U0074 code on a 2018 GMC Sierra?
A diagnostic scan tool, a multimeter for testing electrical continuity, and a wiring diagram of the CAN bus system are essential for troubleshooting.
10. How much does it cost to fix the U0074 code on a 2018 GMC Sierra?
The cost varies depending on the issue, but it can range from $100 for minor wiring repairs to over $1,000 if a control module needs replacement and reprogramming.
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