Does your Duramax have a problematic FICM?A bad FICM on a Duramax can cause your vehicle to experience poor performance. Some signs of a bad Duramax FICM include difficulty starting, the engine running roughly, and misfiring injectors.
Herein is a detailed look atsigns of a failing Duramax FICM and effective fixes.
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What Does a Duramax FICM Do?
The Duramax FICM (Fuel Injection Control Module) controls how the fuel injectors function by sending electrical impulses to open or close the valve. It sends 48 volts to the injector coil, allowing the valve to open and release fuel into cylinders.
Duramax FICM Problems
Problems with your Duramax FICM may range from:
- Bad connection
- FICM wiring harness issue
- A fried FICM
- Bad or low battery
A wiring harness issue can also result in a voltage problem, blowing the FICM.
What Causes FICM Problems on a Duramax?
The leading cause of FICM problems on a Duramax is a dead battery. The low voltage in your dead battery increases the current reaching the FICM.
When the current increases, it’s likely to damage the FICM’s circuitry. With a damaged FICM power supply, there will be insufficient power to start or run your engine.
How Do You Know If You Have a Bad FICM?
Below are various signs that will help you know that you have a bad FICM:
Hard to Start
A bad FICM won’t provide adequate power in the injectors to control fuel injection. As a result, there will be no fuel to burn and power the engine.
If the injection process takes longer to release fuel into the cylinders, you’ll experience an engine that’s hard to start. Failure to fix a bad FICM can aggravate the problem.
You’ll need to inspect the battery and alternator to see if they supply power to the FICM. If not, charge the battery. You may also have a bad battery and alternator, so check and replace them if they’re faulty.
Engine Runs Roughly
If you have a bad FICM but your engine starts, you may notice that the engine doesn’t run smoothly. Sometimes, the engine will start after a few attempts and run rough throughout the drive. When this happens, your FICM power supply is faulty and doesn’t supply the needed power.
You can fix this issue by repairing the FICM power supply.
Sudden Loss of Power
A sudden loss of power to your engine can result from a bad FICM. Most people mistake this problem, believing they’re dealing with a bad fuel injector. While this can cause sudden power loss to the engine, check the FICM unit for any failure.
If your FICM is the culprit, the issue may result from a faulty fuse or a problem with the power side. Check the power side or the fuse of your FICM. If they appear damaged, consider replacing them.
Misfiring Injector
Another sign of a bad FICM on a Duramax is when the fuel injector keeps misfiring. When this happens, the engine can sputter and cause excessive vibration in your vehicle. The injector misfires when starting the engine or running it.
If the FICM is the cause of the misfiring fuel injector, the culprit is usually the module’s logic side. The logic side of the FICM sends messages to the injectors. If the information is wrong, the injector will misfire.
You can solve this problem by repairing the logic side of your Duramax FICM. If the problem is beyond repair, change the FICM. Installing a new FICM allows for proper control of fuel injection.
Excessive Smoke
Excessive dark smoke from the exhaust indicates that your engine’s internal component, including the FICM, is faulty. A bad FICM causes a low-voltage power supply to the fuel injectors.
When this happens, the injectors become slow and disrupt the timing of fuel injection and combustion. This results in the release of excessive smoke from the vehicle’s tailpipe.
To fix this issue, determine the cause of low voltage. If it’s the FICM, its power side is the culprit and needs replacement. This is a cost-effective method instead of replacing the entire FICM.
What Codes Will a Bad FICM Throw on a Duramax?
When a Duramax FICM is bad, it sends codes such as U-0105, P0611, P0335, and P0340. These codes indicate the following:
- U-0105: This code indicates lost communication with your FICM.
- P0611: This code indicates a non-voltage modified FICM. It means the relay system is experiencing internal issues.
- P0335: The code indicates the CPK circuit is faulty
- P0340: The code indicates the CPM circuit is faulty
- P1379: It means the system voltage is out of range
- P1378: It means the FICM voltage is low
Fixing the FICM Problems
Most of the Duramax FICM warning signs start to occur before the entire component goes bad. If you detect them earlier, it’s advisable to fix them. So, let’s discover how you should have each problem fixed.
- Voltage issue: A voltage issue arises from a bad connection or damaged wires. Inspect the FICM system for bad connections, and if any, secure them by unplugging and plugging them back firmly. In the case of damaged wires, replace them.
- Bad or low battery: Try charging your battery until it’s full. Use a multimeter to check if it’s fully charged. If it doesn’t charge, consider replacing it.
- FICM wiring harness problem: Inspect the harness for signs of wear and tear. If it appears damaged, replace it.
- Fried FICM: Voltage issues can blow out your FICM, especially the fuse or power side. Replace them if they appear blown out.
Can You Fix the FICM Problem Yourself?
You can fix FICM issues that arise from a bad battery or alternator. In this case, you only need to replace the battery or alternator. However, if the problem is with the FICM, you’ll need some mechanical skills to fix it.
To avoid relying on guesswork and causing more problems, call a specialist to fix a bad FICM on a Duramax.
Where To Get the Best Duramax FICM Repairs
Do you have a bad Duramax FICM and don’t know where to find the best repair center? Below are several repair centers and dealers you can reach out to and have your FICM repaired or replaced.
- GoECM – Houston, Texas
- SIA Electronics – North Minnie Ave, Tilden, Illinois
- Auto-Truck Services, Inc – Juanita, Colorado Springs
- Stauffer Diesel Inc – New Stanton, Pennsylvania
- Diesel Care and Performance Inc. – Memphis, Tennessee
