An Injector Control Module (ICM) is a device that provides the proper voltage to the fuel injectors in the 6.0 Ford Powerstoke Diesel. This voltage is crucial to the performance of the fuel injectors, and thus, the engine itself. The part may interchangeably be called a Fuel Injection Control Module (FICM).
It should be noted that the 7.3 Ford Powerstroke Diesel utilizes an injector drive module (IDM).
A minimum of 48 volts is required to operate the engine properly. Voltage of lower than 48 volts will result in a variety of operating problems. These problems can be challenging to find if you don’t recognize the potential problem as being the ICM and low voltage. Keep in mind the engine may still run at lower than 48 volts, but its drive-ability will be affected. Eventually, if voltage is reduced too low, the engine will fail to run.
Check the output voltage on the ICM by removing the bolts on the cover. Once the cover is off, use the screw under the cover as the positive. If the voltage does not read 48 volts (or very close to it) it should be replaced. Many replacement ICM’s offer slightly higher voltage than the 48v required for proper operation. These ICM’s may provide better fuel mileage along with an improved throttle response.
When checking the ICM it is also a good opportunity to check for corrosion in and around the ICM, its connections and at the wiring harness. To check the condition of the harness, tug on it slightly while the engine in operating. If you notice a change in the engine’s operation when you tug, it is likely there is a problem with the harness. The only fix for a bad harness is replacement.