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Old 12-30-2010, 06:21 PM
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94 Wrangler PCM questions

My 94 yj wrangler 2.5L 4 cyl wouldn't start. I pulled a plug and checked but had no spark. So far i have replaced the rotor, the dist. cap, ign coil, dist. pick up sensor, (CPS) crankshaft position sensor and I still dont have a spark. everything cranks fine and I also have the smell of gas out the exhaust. when I turn the ignition on, I only have the seat belt indicator lamp and brake light. These lights are normal but i dont have the check engine light or up-shift at any time or other warning lights. I checked all fuses under the dash and also the fuse box infront of the battery both visually and with a continuity tester and they are all good. I also exchanged the auto shut down cube, but i still dont have a spark. I dont have a computer error code unit to use.
I unplugged the 60 plug wiring harness that goes to the pcm and have tested the ones that seem related to my problem including cavity 4,5,9,11,12,20-24,32,44,54, and 57. I tested for voltage always hot, Ignition on, and cranking.
Im confused as to why K19 (ignition) doesnt have voltage always or ign on, but do have while cranking. I would think it should always have voltage to K19.
At 21-24 i dont get a test light. should I?
Can someone explain to me how to properly test for the 5 volts at sensors please?
Can you please help me trouble shoot it from here. Trying to get this going with my dad and were going crazy!!! Please help with any trouble shooting suggestions. Thank you VERY much.

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Old 12-31-2010, 03:22 PM
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testing 5 volt reference voltace should better be done with a DVOM that has at least 10 megohms of internal resistance. Be sure yours is or you might destroy the PCM and not realize it. Checking to see if you have voltages in and out including reference voltage is the place to start. Any voltage missing as an output from the PCM indicates a defective PCM. I think yours is given you have replaced everything else that would cause the issue.
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