94 GC No Fire Low Voltage to Pump

[docscomputers]

Originally Posted by dksob81

Yes we are talking about the same things the PICK-UP COILD (in the distributor) is also known as the CamShaft Position Sensor.

To test the operation of the camshaft position sensor,

(1) Connect the positive (+) voltmeter lead into the
sensor output wire. This is at done the distributor
wire harness connector. For wire identification, refer
to Group 8W, Wiring Diagrams.
(2) Connect the negative (-) voltmeter lead into the
ground wire. For wire identification, refer to Group
8W, Wiring Diagrams.
(3) Set the volt meter to 15 VDC (or the closes to 12VDC, but no less then 12 VDC) While observing the Voltmeter crank the engine, the voltage should fluctuate between 0 volts and 5 volts.

Signal/output Wire - GREY/BLACK
Sensor Ground - BLACK/LIGHT BLUE


Did you try leaving the key in the ON position to see if the CHECK ENGINE light eventually comes on and start the jeep?

I was going to try that but didn't see much scence if the coill was open, I picked up a new coil tody and test the leads and it had a 786 ohm reading. But I will try the crank test tomorrow to see if it is pulsing power to the pickup coil just to make sure it is getting power to it. That would be a wise thing to do I guess. I Tried leaving the key on and like I said if it is cold out it will not do anything, If it warms up a little than it works.

[dksob81]

well that wouldn't explain the CHECK ENGINE light not coming on, unless the CHECK ENGINE light bulb is blown.

[docscomputers]

Well I Managed to get the pickup coil on yesterday and the jeep would at least start, But it still is not 100% It was warm outside so not sure if the temp had anything to do with it or not. But heres what a got. The fuel pump is running constantly for about 5 minutes and you can here the relay ticking constanly the hole time, When the check engine lite comes on it will start. Yesterday after running it for a couple hours it just shut off and would not start back up, Any Ideas? What else could cause that? I did put a used pump on it and I took the new cps back for refund. Both the old and the new cps tested ohm at around 800+ and the old pickup coil will now get a intermitent ohm reading, willl not read when it is cold but soon as you warm it up it reads 700+ ohm.

Confused
Tom

[docscomputers]

Funny thing, I tested the voltage coming from the CPS to Pickup Coil and I have a constant 4.96v with key off and out of ignition. No fluxuation in voltage after cranking engine.

Tom

[dksob81]

You shouldn't even have any voltage to either with the key in the OFF position.

[docscomputers]

That's what I was thinking. Must me a dead short in some wiring harness somewhere. Something pulling voltage in the ignition maybe like the key is stuck on or maybe a bad switch. I gues I'm got to get in to wire test mode and see what I can figure out. This jeep also has a DEI Valet 471T Remote Start in it. May be something there. Have any suggestions?

Tom

[dksob81]

The remote starter could be the problem.
Check for broken wires at the PCM connection, I have had a few wires break here.

[xj31]

I still think it sounds like a bad pcm,especially since you said"The fuel pump is running constantly for about 5 minutes and you can here the relay ticking constanly the hole time, When the check engine lite comes on it will start."
I have seen this quite a few times.I know you said you replaced the computer but where did you get it from?

[docscomputers]

The PCM is a junkyard model. Trying to keep from spending a lot of money on it. How do you do a self diagnostic on the jeep or do you have to have a PC Diagnostic Code Reader? Think I should try another?

Tom

[dksob81]

Whats the part # on the PCM? I have a KNOWN GOOD PCM for a 94 Laredo 5.2L engine.

[docscomputers]

I'll Check the part number a little later today but I do not think they will be the same, Mine is a 4.0L

Tom

[docsplace]

The Numbers off the PCM are 56026993 10.0941-0902.4 3X1 910

I haven't had a chance to work on that for a few days so I have nothing new to report other than i'm going to try to hook up the old pump temperarely outside the tank to see if it will initiate and just try to see if I can find some broken wires, Still don't understand the constant 5v to the Pickup Coil.

[docsplace]

Originally Posted by dksob81

Whats the part # on the PCM? I have a KNOWN GOOD PCM for a 94 Laredo 5.2L engine.

dksob81 What are the numbers off your PCM and What is your price?

Thanks
Tom

[dksob81]

the part # is 56026113, but I doubt if it will work because it is for the 5.2L engine.

[bringselpup]

56026993 doesn't seem to match what I'm seeing you need. Is that the Junkyard computer or the original one before you swapped?

Look here http://www.autopart.com/ecc/ECC1994J...NDCHEROKEE.htm

They will rebuild the original one for $149.00 also

http://www.autopart.com/ecm/chrysler.htm