The Ford 6.0L Powerstroke PCM (Powertrain Control Module) and FICM (Fuel Injection Control Module) are critical components in managing the engine's performance and fueling. Calibrations for these modules are intrinsically linked and finely tuned to optimize fuel delivery, timing, and other parameters to ensure efficient and reliable operation of the engine.

The majority of the authority for the engine calibration is in the PCM,

while the FICM does the actual work of opening the injectors through an

electronic device called a driver. The driver can be considered a high-

current switch that has no moving parts. The FICM also internally

generates the 48 volts that the 6.0L HEUI system uses.

Here's a brief overview of what each module does:

PCM (Powertrain Control Module): This module controls various

aspects of the engine's operation, including fuel injection timing, air-fuel

ratio, turbocharger boost pressure, and more. It collects data from

various sensors throughout the engine and adjusts settings accordingly

to optimize performance and emissions.

FICM (Fuel Injection Control Module): The FICM is responsible for

controlling the fuel injectors. It regulates the timing and duration of fuel

injection pulses to each cylinder based on inputs from the PCM and

various engine sensors. This ensures proper fuel delivery for combustion.

The FICM is a fully capable ECU for an International engine. It

has the ability to operate the engine independent of the Ford ECU.

So, when the Ford ECU is programmed, it sends requests to the FICM

based off of information like mass fuel desired, rpm, icp, and other

information. The FICM ultimately has the final say. The keys to the fueling

castle, if you will. 

In the FICM, each individual injector is controlled with four driver

inputs.  There are high- and low-side drivers to open and close the coil of

each injector. On later 6.0L engines, the low-side driver is actually shared

among four injectors. This means an injector short to ground on one of

the low-side drivers could produce four different cylinder error codes. The

first ('03) engines had an individual low-side driver for each injector.