zero volt ficm

[eabrust]

Originally Posted by International350

Had problem with my truck shutting off while driving. It would shut off, crank back up after 30min and a day later do same thing. Did for about 2 weeks now no start. Ficm is reading zero volts on all the 4 screws. Replaced ficm, all fuses, all relays, and still reading zero. checked the wiring and am geting volts to ficm. After reading FICm diagram it reads that ficm wont sync if crankshaft sensor is bad. Does that mean that it will register zero? any other thoughts?

International,

Sounds like a chafed wire somewhere, or bent pin on connectors, if you've been through all fuses. I don't believe the crank sensor is issue. By sync, they mean the FICM won't pick up timing in relation to the engine to fire correctly, but that won't prevent a power up, it will only prevent any injectors from firing.

As I follow the schematic, the first thing that happens at key on, is a 12V 'key on' signial is provided to the FICM. The FICM then must internally power the logic (make sure the FICM logic fuse is good), and then the FICM commands the MPR output ( which engages the main relay to power the FICM power side. Sounds like you are measuring the key on signal getting to FICM, but it isn't engaging the relay for main power?

I assume you've been looking at the FICM Guide pdf that can be found via googling (I'd attach it, but it's 5MB).

If your truck was intermittently dying, and then restarting after cool down, it could also be an internal board fault or solder joint in the FICM that is temperature sensitive (or was till it finally failed for good).

Good luck working it out.

Eric