is an assembly containing four relays controlling the:
- PCM power;
- fuel pump main power;
- ECT cooling fan low and high speed;
- AC clutch;
controls the voltage fed to the fuel pump, according to "commands" received from the PCM.
The PCM sends a 5% to 50% duty cycle to the fuel pump driver module which then powers the pump at 10% to 100% of full capacity. The FPDM returns a 50% d/c signal to the PCM to indicate all is well.
Signals from the PCM of 0% to 5%, 51% to 67.5%, or 82.5% to 100% are invalid, the FPDM will return a 25% d/c signal to the PCM.
A PCM signal of 67.5 to 82.5% command the fuel pump off, the FPDM will return a 50% d/c signal to the PCM.
More about how that works here
Here are the wiring diagrams for the CCRM and the FPDM/pump
- 2003 GT, UPR X, FRPP 24lb/h, Magnaflow, PP 70mm TB & plenum, Delta Force tuned,
Steeda UDPs, Ralco flywheel, RAM HDX clutch, 3.73s, 262 rwHP/305 lb-ft.
New ride (7/1/2013) 1998 Mercedes SL500-5.0L 32V VVT 326/347 HP/tq