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Signs of a Bad FICM on a Duramax

Signs of a Bad FICM on a Duramax

It is not difficult to check bad FICM as you have to use a voltmeter to determine the voltage that needs to be more than 48 volts, ideally. Moreover, it is better to recognize and solve the problem in the vehicle’s component to prevent it from getting worse, as you can replace or repair the faulty FICM to make it functional.

Signs of a bad FICM on a Duramax include misfiring injectors, difficulty starting a vehicle, and a smell of fuel that is strong enough to be detected. Moreover, a clicking sound is produced, and a cloud of smoke begins to release from the tailpipe. Furthermore, it causes loss of power, rough idling, and overheating of the system, leading to poor fuel economy. 

FICM stands for Fuel Injector Control Module, an electronically controlled unit inside the engine. It controls the functioning of fuel injectors by opening and closing the valve.

They are usually on the diesel engine like Duramax, designed by General Motors and installed in vans, pickups, and SUVs.

This module is mounted with brackets and located on the surface above the valve cover on the driver’s side. It can go bad or gets cranky sometimes when there are issues in the wiring.

Furthermore, weak batteries can be responsible for loss of function, providing low voltage and damaging the internal circuitry, and the symptoms begin to appear.

A few visible symptoms of a bad FICM on Duramax indicate an internal issue with the module that needs to be fixed to restore its function.

Difficulty in starting a vehicle 

The vehicle cannot start when there is an issue with FICM because this module controls the injection of fuel that has to be burnt to produce power to allow its movement.

This injection process takes more time than usual when the module is not capable of providing power resulting in a delay in the engine’s functioning.

Proper detection of battery health is essential when you find the vehicle hard to start, as weak and damaged batteries can make them faulty.

You have to check the batteries regularly to keep them functional and replace them if these are responsible for the loss of function in FICM.

Misfiring injectors 

The injectors transfer fuel into the combustion chamber to form a combustion mixture. A valve on the nozzle efficiently controls the amount of diesel fed into the chamber.

Diesel reaches the injectors when pushed by the fuel pumps and reaches there through fuel lines. Any issues in the FICM lead to uncontrolled diesel volume in the chamber, leading to misfires.

It can also happen due to dirty injectors not being cleaned regularly, but the module problems can also make them cause a misfire.

Moreover, this issue is seen when you try to start the engine as it leads to the generation of vibration in the vehicle and causes sputtering of the motor.

It is better to identify the problems and repair or replace the Duramax FICM if it cannot be repaired.

Furthermore, the replacement can help revive the engine performance when the injectors can control fuel volume.

Strong fuel smell and clicking sound 

One of the most prominent systems for a bad FICM is the strong smell of fuel from the exhaust system that can be easily detected when you are standing close to the vehicle.

It smells like a chemical having a pungent smell, like varnish, that can irritate you. Moreover, a particular sound will be produced that sounds like a working typewriter.

In addition, it can produce a clicking or knocking sound whenever you try to start the vehicle and indicates a need for fixing the bad FICM.

Furthermore, all of these symptoms, including loud sound, overheating, disturbance in engine performance, and poor fuel economy, are amplified in cold weather.

Sending failure codes and overheating

The FICM relay is controlled electronically, giving the engine power for combustion and making it run. It begins to send codes when there are issues in the relay system.

Moreover, you will get a code U-0105, which means the Lost Communication with FICM indicates a need to repair the damaged components.

In addition, you can also get a 611 code which stands for non-voltage modified FICM indicating problems in the relay system that is facing some internal issues.

However, the problem can be with the logical unit if there is no voltage and a disruption in power delivery is observed.

Furthermore, it can also cause overheating of the engine when the unburnt fuel particles reach after some time due to delayed injection.

Therefore, you have to figure out the issue with the relay system quickly when you see the failure codes to protect the engine from overheating and other related problems.

Rough idling

The engine begins to show rough idling for some time when the FICM goes bad, but it can stay for long, resulting in an uncomfortable riding experience.

Accordingly, the engine works slowly, leading to a decrease in the RPMs. It will be at risk of damage due to the partial combustion of diesel as the unburnt fuel begins to build up on the walls of the cylinder.

In addition, it can negatively impact the engine’s components, like the exhaust system and spark plugs, when used in the same way for the long term.

Loss of power is a symptom of bad FICM on a Duramax, so you have to check the control module before changing the injectors randomly.

You can fix it by replacing the faulty power side or power side unit.

Furthermore, it is essential to repair the fuel injector’s control module.

Poor fuel economy 

Any issues in the FICM affect the combustion process, as the required amount of diesel cannot enter the chamber for burning.

Moreover, it will ultimately affect the vehicle’s performance, which means there will be poor fuel economy.

The weak batteries produce a low voltage that is insufficient for quick opening of the injector valve, which means the engine will lose power due to less fuel in the combustion chamber.

The retardation of injection timing causes the slow injection of fuel, which gets wasted due to entry at an incorrect time when the combustion process is complete.

So, the bad FICM is related to poor fuel economy because the amount of wasted diesel is greater than that which is combusted to produce power.

Excessive release of smoke 

The release of smoke is a common symptom that indicates an issue with the engine’s internal component, which can be FICM.

Smoke will produce when there is a disruption in the timing of combustion and fuel injection duration, leading to the release of white smoke from the tailpipe.

The duration of injectors to release the diesel gets disturbed when there is no proper voltage supply, as the electrical impulses are responsible for the opening of valves.

Furthermore, the only solution is to provide a voltage to FICM through other means or seek professional help to figure out the issue and fix it.

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