Crank Sensor/PCM

[4weeln]

Hello all...
I have a '94 JGC 4.0l all time 4 wheel drive thats been giving me hell. anyways I think I've narrowed it down to ehter a bad crank position sensor or a grounding issue with the PCM. the sensor I'm told is located on top of the bell housing. is this and easy fix? never done it before.

[greasefingers]

What are the symptoms? From my understanding, if the PCM does not receive this signal, then the engine will not start. It is easy to ohm-out. It has a high resistance across the two wires. And yes it is mounted on the bellhousing, but small hands are required. The harness extends out however, making it easy to measure.

[greasefingers]

You can visually see the crank sensor by looking at the bellhousing on the drivers side. There is only about a 2” gap to peek in. The harness however is routed around to the passenger side. The connector is just behind the oil filter and just above the starter motor.

[4weeln]

haha... I've figured out that small hands are required wich I don't have. Anyways
the symptoms are: while not start easily by this I'm mean there will be about 5-10 min of gradual clicking from the fuel pump and auto shutdown relays. while this is happening the check egine light flashes in sync with the clicking this will gradually stop and the check engine light will stay solid for a couple sec. then I can start the jeep but its only gotten worse I'm lucky if she'll even start to click.

[greasefingers]

Well you definitely have an electrical problem rather than a fuel delivery situation. The PCM is opening the ground for the ASD (automatic shut down relay), for some reason. It could be one of several reasons. The crankshaft sensor, camshaft sensor, or the battery is not holding a charge. On some Jeeps, when the start-up voltage is too low, the PCM freaks out well before the battery is rendered useless.