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Unread 11-24-2011, 11:23 AM   #1
redgolds
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1991 YJ Wrangler 
 
Join Date: Nov 2011
Posts: 10
YJ ignition problems, Please help

Howdy all, I have been lurking in the shadows for a while now reading and searching various things on this great site. I am a new jeep owner. its a 1991 wrangler 2.5l with 33's and a 4 inch lift. nothing special but its fun to drive.

The previous owner installed a new radio. He did an absolute terrible job. Spliced into things cut wires and left them hanging. I got almost all of it figured out and tucked away. But in doing this, my jeep lost its spark. I have voltage going to the distributer but not going to the plugs. My buddy is a caterpillar mechanic. so he came over with a probe of some sort, and hooked it to a green wire with a black stripe that came off the distributer, and he got it to start. We traced the wire through the harness and it leads to the computer. I guess my question is where does the distributor get the signal to fire the plugs? Again, He got the jeep to start and run, ran for maybe 5 minutes but as soon as he took his probe off the wire, the jeep shuts off and has no spark, but when we put power to the green wire with the black stripe, it will start. any help on this situation will be greatly appreciated. sorry for such a long first post. Happy Thanksgiving to all!!!

Jamie

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Unread 11-24-2011, 11:40 AM   #2
jhumphrey
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1998 XJ Cherokee 
 
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Im not sure what he used, as he's a mechanic, so maybe it was some sort of bypass device. My guess, based on what I read, would be that the ICM (ignition control module) is shot OR the ECM (engine control module). It could've happened when one of the wires from under the dash grounded something out. Your ECM is under your dash, on the passenger side. ICM is under the washer fluid tank on the driver side fender.

I would also test the ignition coil, to make sure its working correctly too. Others more seasoned than I will chime in soon

Happy t'giving to you too!
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Unread 11-24-2011, 11:54 AM   #3
redgolds
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1991 YJ Wrangler 
 
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Thanks for the reply J. The "probe" was pretty nifty. It hooked to the positive and negative on the battery. so he could power anything in the jeep by putting power to the wires with the probe.

Is there any way to see if those modules are bad? a test of some sort?
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Unread 11-24-2011, 11:56 AM   #4
Alfons
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1992 YJ Wrangler 
 
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Location: Ontario, Canada
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The wires around the ignition switch may have been modified & in your attempt at re-wiring, you may have left something unconnected. If you can follow a wiring diagram, send me a PM containing your email address & I'll send you a Wiring Section from a Factory Service Manual. This will show you all the harness layout and connections as well as detailed schematics of each circuit and should be what you need to patch up some else's butchering job on your wiring.
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Unread 11-24-2011, 12:09 PM   #5
redgolds
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wiring

You have a Pm Al
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Unread 11-24-2011, 12:59 PM   #6
redgolds
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any one else have any ideas to check?
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Unread 11-24-2011, 01:03 PM   #7
Xpress
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Go back through and re-connect everything?

I seriously hate it when people try to make their own "custom wiring harness" for their sound system and they leave it all messy. I'm not the cleanest guy when it comes to wiring, but at least I tape all of the stereo wires together, and label each one so I know which is which.
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Unread 11-24-2011, 01:49 PM   #8
stevedude19
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Last Friday my amp had a short and fried my ecu. I think if my deck would have had a fuse it would have prevented it. The po aswell did a horrible job with the wiring to the deck
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Unread 11-24-2011, 03:38 PM   #9
redgolds
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yea im kinda anal when it comes to wiring. I try to do the best I can to prevent fuses popping for unknown reasons, and prevent fires or anything like that. Plus it just looks better and easier to trace wires. There where wires just spliced together not taped, bare wires exposed in 2 different spots. I took out over 100 feet of wire that was for the radio and speakers. Thats no bull crap!

I went back through and traced almost every wire under the dash. Thinking I may have cut/smashed a wire somewhere. I didnt find anything. I even went as far as to unhook every wire for the stereo from its power source to see if that helped. It didnt.

The radio I put in, has a fuse and it wasnt blown. I am at my wits end. I hated wiring before messing with this thing, and I even hate it more now!!!!
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Unread 11-24-2011, 03:50 PM   #10
jsawduste
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2006 YJ Wrangler 
 
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Quote:
Originally Posted by redgolds View Post
hooked it to a green wire with a black stripe that came off the distributer, and he got it to start. We traced the wire through the harness and it leads to the computer. I guess my question is where does the distributor get the signal to fire the plugs but when we put power to the green wire with the black stripe, it will start Jamie
Jamie,
let me help you out here. This green/black is the reference voltage for the sensors.

The green/black wires starts at the back of the alternator.

Goes a few inches and then splices. One end of the splice goes to the coil. NOT the Distributor. The other end of the splice goes to the ASD (Automatic Shut Down relay) in the PDC (Power Distribution Center...fuse box) under the hood by the battery.

From the PDC the same wire heads to a big splice and heads to each sensor. Ultimately ending at the ECM.

What your buddy did was bypass the ASD relay with his probe.


Start at the alternator and clean the connection. Follow the wire to the splice and check that.and the connection to the coil. There is a Weatherpack connector that joins the alternator harness to the engine harness. Check that connector and so on till you have reached the ASD.

Somewhere between the alternator and the ASD you are loosing continuity.
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Unread 11-24-2011, 05:28 PM   #11
redgolds
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Jsaw and others that have posted.

Thanks a bunch. I will be checking the wiring tommorrow after work.I plan on cleaning all the connections under the hood with cleaner, and all my grounds, aswell as what you suggested. Thanks again, I will post the out come sometime this weekend.
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Unread 11-24-2011, 05:50 PM   #12
redgolds
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Ok I had to go check your now, i couldnt wait. Jsaw, your right, the green and black wire runs to the coil. but the fool that had this jeep before me cut and spliced a yellow wire between the green wire and the coil. for what reason, I have no freaking clue.

another question here. There is a green wire with a inline glass style fuse that is suppose to run to the starter. It wasnt hooked to the starter the other day. it was laying next to the splice in the wires for the coil. I wonder if this green wire was spliced into the wires running from the coil? What the hell would be the reason if thats the case...??
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Unread 11-24-2011, 06:39 PM   #13
jsawduste
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Post answered in a PM. Good luck dude. Sounds like the PO did a real hack job.
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