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-   -   Jump mistake now crank no start (https://www.cherokeeforum.com/f5/jump-mistake-now-crank-no-start-230262/)

rbridgham 10-19-2016 08:19 AM

Jump mistake now crank no start
 
It was very dark out this morning and I made the mistake of crossing jumper cable wires on my 99 Grand Cherokee. (The Cherokee has the bad battery.)
I was able to jump it yesterday afternoon. When I try to start it after the mishap I get a crank, no start situation. All lights work fine but I noticed the fuel gauge and battery gauge are not doing anything.
Can I please get a productive recommendation of things to troubleshoot such as fuses or whatnot? Anything serious and this bad boy is going to the scrap heap as I am sure that it is cursed.
Thank you so very much.

dave1123 10-19-2016 10:14 AM

My recommendation is to take the PCM to someone and get the power supply tested. There's an internal power supply stage for the 5 volts for the electronics. You may have damaged it with the reverse polarity or triggered a fail-safe function.

Jeepin'_Aint_EZ 10-19-2016 10:52 AM

My question would be, how long/how many times did you crank it with reversed polarity? More than likely, like Dave said, the PCM is how I like my bacon..... crispyyyyy

Ender 10-19-2016 10:57 AM


Originally Posted by Jeepin'_Aint_EZ (Post 3319103)
My question would be, how long/how many times did you crank it with reversed polarity? More than likely, like Dave said, the PCM is how I like my bacon..... crispyyyyy

I second this... bad mistake :oops:

caged 10-19-2016 06:32 PM

yep. smell your pcm, i bet it stinks now. you may even see the burnt jelly in there.

Bustedback 10-19-2016 07:51 PM

Check the fuses.

97grand4.0 10-22-2016 10:11 PM


Originally Posted by Bustedback (Post 3319290)
Check the fuses.

Yep. Grab your DVM and backprobe the fuses in the fuse block under the hood. Make sure everything has voltage that is supposed to first, key on engine off. PCM is sure a suspect but let's do the basics

94zj318 10-23-2016 06:37 PM

I accidentally fried my '94 ZJ's PCM by doing that, and blew all of the fuses and relays... gotta be careful about what you're doing, you most likely fried your PCM. :(

dave1123 10-23-2016 09:23 PM

Don't blame the jeep for a mistake YOU make!

NewbJeep 10-24-2016 07:06 AM

Geez man glad you're ok. You may have fried your pcm but at least your battery didn't explode in your face

caged 10-24-2016 07:55 AM

yep, the guy that did that at my shop, used my new TJ to jump his 95 xj. at least he hooked the cables up properly on my TJ. not that it matters, but my jeep still ok. this was many years ago.
it fried his pcm, and blew his buss fuse for his alternator.
you could tell where it blew in his pcm when you take the cover off. it was like toasted jelly and stunk like melted crap.

and yeah, you're lucky the battery held up.


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