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Help us help you. By posting the year, make, model and engine near the beginning of your help request, followed by the symptoms (no start, high idle, misfire etc.) Along with any prevalent Diagnostic Trouble Codes, aka DTCs, other forum members will be able to help you get to a solution more quickly and easily!

1993 jeep crank no start

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2 years 1 month ago #62793 by Dunncr
1993 jeep crank no start was created by Dunncr
I have a 1993 jeep grand Cherokee 4.0l no start. Long story short I found one of the 2 5v ref circuits with 15.5v. Has anyone seen this before? I ended up cutting the wire and still has the 15.5v coming from the pcm. I assume the pcm is bad but I was just wondering if anything else could cause this. 
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  • Noah
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2 years 1 month ago #62798 by Noah
Replied by Noah on topic 1993 jeep crank no start
15.5 Volts DC? Do you have a battery charger on it?
It's hard to get more than battery voltage on a reference circuit.
"Ground cannot be checked with a 10mm socket"

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2 years 1 month ago #62810 by Chad
Replied by Chad on topic 1993 jeep crank no start
The first thing I would check is the PCM Powers and, especially, Grounds. The voltage regulator, internal to the PCM, requires a good ground to reduce system voltage to 5 volts.

15.5 Volts DC? Do you have a battery charger on it?

It's hard to get more than battery voltage on a reference circuit.


I remember a ScannerDanner Premium video where a Ford Explorer had 29 volts on the PCM power feed.    
"Knowledge is a weapon. Arm yourself, well, before going to do battle."
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I have learned more by being wrong, than I have by being right. :-)

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2 years 1 month ago #62865 by Noah
Replied by Noah on topic 1993 jeep crank no start
I remember that. I went to work the next day and pulled that fuse on Ranger and got the same results. Then a friend of mine a few years later excitedly showed me a case study he was working on with the same issue, lol.
Curious to know how this one plays out...
"Ground cannot be checked with a 10mm socket"

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