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post #1 of (permalink) Old 11-12-2008, 04:24 PM
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how to test the PCM

I posted in the past about the stinky YJ that I got out of a farm field. I am happy to report that the smell is gone.
My problem is I cant get spark. I have tried the following.

94 YJ 2.5

plugs and wires
distributer cap and rotor
checked coil both primary and secondary res check out
replaced the crank pos sensor
checked all under hood fuses
Replaced emergency shut off relay
I am going down the road of doing a Continuity check of all the wires from the under hood fuse block to the PCM and coil.

All I can see that is left is the PCM.
How can I check if the PCM is working. I tried to put it in self Diagnostic mode but none of the idiot lights came on except the brake light. The jeep dealer said they cant do a diagnostic without the PCM attached to the truck. The car is in a million pces in my garage.
Any help would be appreciated!!

Last edited by wr400f; 11-12-2008 at 06:45 PM.
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post #2 of (permalink) Old 11-12-2008, 04:36 PM
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Kevin, you made it! Welcome to the board! This morning I checked with the full-time, paid IT guy and he said that you weren't even registered. I showed him a screen dump of your profile, and that must have led him to the problem.

Number two, a Jeep isn't a car. You're new to all this, so we'll let it pass this time. Next time you slip you'll be severely beaten with a wet spaghetti!

I'm not up on the new-fangled Jeeps, and don't know the details of troubleshooting the ignition system. So, being ignorant of it all, I'd try to borrow a PCM from a buddy with a running Jeep. Beyond that, someone who knows more about them should chime in soon.

EVERYTHING's easy for the guy who doesn't have to do it.
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post #3 of (permalink) Old 11-12-2008, 05:40 PM
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I had a similar situation a few weeks ago... Here's a link to my post.. I sent mine in through O'rielly's to have it tested to make sure. I have some pics of what they look like inside when they are toast.....

Need some help 91 YJ
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post #4 of (permalink) Old 11-12-2008, 06:53 PM
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Silent Bob
Your a lifesaver... Im assuming that your problem was no spark. Just as you did, I went through the step by step and did it twice because computers just dont go bad often.
The only thing I have on the idiot gauges are seatbelt and brake. (brake just stopped going off). If you dont mind me asking what did the people you went to charge for repairing/replacing your computer. I have quotes of about $189.00 if I send mine in and they repair it or $495.00 to get a reman from the dealer. Hate to sound cheap, however I am always looking for a deal. This rescue project is putting a hole in my savings account.

Thanks for all your help. I tried another forum site and it sucked. Lots of reades but no help.
As far as calling my Jeep a car I dont know what your talking But if I were to make that mistake I can assure you it will never happen again..
post #5 of (permalink) Old 11-12-2008, 07:07 PM
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Yep, no spark. Had a seatbelt light on the dash and that was it.... The $189 sounds about right to send it off and get it fixed. They said it would only take about two weeks but it ended up being three weeks and I complained a bit and they cut it down to $150 ish....
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