5 Signs of A Bad FICM On A Duramax Engine

Wondering what are the signs of a bad FICM on a Duramax engine? The most common sign you can find is hard start.

Often it’s too late by the time you realize that there’s something wrong with your FICM. But if you observe closely, you can find out the symptoms before it’s too late.

The Fuel Injection Control Module (FICM) works as the power and control provider to the fuel injectors. The power side of the FICM ensures the supply of 48 volts of power to the injectors. Without this certain amount of power supply, the fuel supply will be restricted, and the engine will fail to start.

However, you can avoid such a disaster by noticing the signs a bad FICM can cause and preventing them with the necessary steps.

Signs of a Bad FICM on a Duramaxand their Solutions

Before completely going bad, the FICM will show symptoms. These symptoms can be diagnosed with professional tools or with the help of an expert.

A bad FICM fails to provide an accurate amount of voltage to the injectors. Consequently, the engine takes longer to start. Often it cranks but doesn’t seem to start. Rough engine, injector misfire, and excessive smoke are some other signs of a 2005 Duramax bad FICM.

Hard to start

When the FICM fails to provide power to the injectors, the fuel injection takes more time than normal. As a result, the engine takes a longer time.

You can check the batteries and the alternators for any defect. It is possible that the damaged batteries and alternators are failing the FICM. It is always good to check on the batteries to see if they are getting charged properly.

Make sure the batteries and the alternators are fine. Repair and replace them if necessary. This will prevent damage of the FICM.

Loss of power

FICM’s failure often causes loss of power to the engine. It is often mistakenly thought to be the result of a bad injector.

It is necessary to check the FICM before changing the injectors. Disabled power side, or bad Duramax FICM fuse can be the root of the problem.

To solve this problem, take the FICM out and change the power side of the unit. The replacement of the faulty power side should resolve the power loss problem of your vehicle.

Rough Engine

A rough engine is one of the symptoms of bad FICM relay. The engine finally starts after a long time of cranking, but the engine remains rough for quite some time.

In some cases, the roughness stays all the time, making the driving experience uncomfortable.

Take the help of an expert to address and repair the FICM problem. This will cost you money, but it will be more affordable than buying a new FICM.

Injector Misfire

Injector misfire frequently happens while frequently starting the engine or constantly. It causes sputter in the motor and vibration in the car body.

The failure of the Duramax FICM logic side may cause this symptom.

Look for the option to repair the FICM. If it’s beyond repair, replace the FICM. A new FICM will provide proper fuel injection control and help your vehicle perform better.

Excessive Smokes

When the voltage supply is low, the injectors become slow. This can cause excessive power in the tailpipe. The messed-up timing and duration of fuel injection lead to producing the smoke.

You can DIY the power side replacement of the FICM. It is the most cost-effective way to repair the FICM. If that doesn’t seem possible, seeking an expert’s opinion is the best you can do.

Apart from these signs, you may notice your Duramax FICM leaking, which is not that common. Most likely, it is the coolant used for cooling the FICM. The leak may be caused by some daunt or some other damage to the FICM. Sealing the place from where it’s leaking should solve the problem.

If you notice these symptoms in your vehicle, try to get to the root of the problem. If the causes turns out to be the FICM, repair or replace it before it affects your vehicle’s performance.

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Frequently Asked Questions (FAQs)

What causes a FICM to go bad?

The chief reason for a bad FICM is the low voltage of the battery. A dying battery fails to provide proper voltage to the FICM causes problems in fuel injection process. Faulty alternators also can cause the FICM to go bad.

How to tell if FICM is going bad?

There will be certain signs of a bad FICM on a Duramax that will point to the issue. The problem in engine start, rough engine, injector misfire, and excessive smoke are some symptoms of bad FICM.

How do you diagnose a bad FICM?

Bad FICM diagnosis requires professional tools. Seek the help of an expert for the diagnosis. Sometimes, you can find the fault by using a multimeter to measure the voltage supply.

How to test FICM on Duramax?

To test the FICM on your Duramax, the easiest way is to use a multimeter to see the voltage. After removing the FICM cover, connect the negative end of the multimeter and the battery. Attach the positive end to the screw nearest to the driver’s side. If the voltage is less than 48 volts, there might be some problem with the FICM.

Wrapping Up

FICM, although a small part, is very crucial and essential to keep the vehicle running. Damage in the FICM means interrupted fuel injection, which leads to the loss of power and overall performance of the vehicle.

Recognizing the signs of a bad FICM in Duramax and solving and preventing them at the right time can save you.It may be a faulty power side or logic side that can be repaired or need a unit replacement. Solving them quickly will save both your time and money.

Keeping an eye on the weary batteries and alternators will prevent the FICM from damaging.

You can obviously ask the experts for help!

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Ronald Berit

Our chief editor, working 24/7 to ensure the precise and only quality data regarding different trucks.He is mastered with the ins and outs of cargo to off-road trucks of Dodge, Ford, Chevy, Toyota, GMC and more. This truck geek graduatedwitha Bachelor of automobile engineeringdegree and practiced through his own automotive parts repair center.

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