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Unread 09-22-2009, 11:14 AM   #1
am9010
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causes for a pcm to fry? went through 2

My 1996 jeep grand Cherokee stalled out one day and i went through enough trouble shooting to realize it was my pcm that was at fault. i tested for power to it through the black connector and continuity. so i replaced it with a junkyard one that IS COMPATIBLE i have a list of serial numbers of pcms which will plug and play and work with my gc. after i put that in it started up re learned its stuff and it worked fora few days till i was driving down a 4 lane freeway on the left lane and it stalled out (33 mts slow you down verrrrry fast at 70mph, it was a ***** shifting lanes to get to the right) just like it did when my previous pcm failed.

so my question is what causes pcms to fry? i have power going to it. i do realize there is a chance i just had bad luck with a junk pcm, however if i didnt and it was a burst of to much voltage going to my pcm wouldn't a fuse or my asd relay blow and close the circuit to pcm before it gets damaged?

any input helps!

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Unread 09-22-2009, 11:19 AM   #2
HighLonesome
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It connects directly to the coil primary, so that is worth a look.
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Unread 09-22-2009, 12:45 PM   #3
am9010
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update: good news my pcm may not be fried, i just found out i do not have power going to it but i have a good ground. i did a continuity test on pin A22 on the black connector because that is the power wire and there was no continuity. pins A31 and 32 both have continuity which are the grounds.

can someone tell me exactly what could stop giving me power to that wire. my asd relay clicks as does every other one
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Unread 09-22-2009, 01:48 PM   #4
BlingBlingZJ
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I dunno its tricky when the PCM starts acting up. I had to pretty much replace every single sensor thinking one of them was shorting out the PCM but it turned out to be the PCM all along.
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Unread 09-22-2009, 02:49 PM   #5
am9010
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son of a *****, i must have been testing my fuse to quickly and didn't realize a 20 fuse blew someone throw a brick at my face, my jeeps running. lol.
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Unread 09-22-2009, 02:54 PM   #6
BlingBlingZJ
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lol .. glad you got it running
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