Author Topic: Trouble shooting  (Read 9708 times)

BennyLT

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Trouble shooting
« on: February 12, 2008, 08:17:44 am »
Ignition system:

Background:  Installing a rebuilt 4.2L in 1989 wrangler.  (I bought a project in process and i'm finishing the install)

Problem: Turns over but wont start using its own ignition system.  (Starts and idles fine using a rescue box bypassing the coil)

while sitting with the battery hooked up the coil has constant power (not sure if is is supposed to or not) it also gets very hot to the touch. 

Where is the ignition module and what does it look like? maybe its a problem with that.   I think i have all the required wires and hoses hooked up.  i still have some things to attach but i think they are all secondary systems that shouldnt have anything to do with starting. ???

Jeep came with a spare ignition switch (plastic box that attaches to the column).  Could the problem be in that switch, maybe the PO was planning on changing it. 

Thanks for your ideas in advance!
89 YJ - work in process
4.2L - bored 60 over - tow cam
Jasper auto trans
Still needs some things to be done before she is ready for the road/trail.

SteveTheFolkie

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Re: Trouble shooting
« Reply #1 on: February 12, 2008, 11:32:39 am »
while sitting with the battery hooked up the coil has constant power
if your key is turned off there shouldn't be power to the coil.  With the key in the "on" or "run" position there should.  The coil is overheating because it's not being allowed to discharge the energy being fed into it.

 What, by the way, is a "rescue box" - pardon my ignorance, just not a familar term to me.

BennyLT

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Re: Trouble shooting
« Reply #2 on: February 12, 2008, 01:05:14 pm »
while sitting with the battery hooked up the coil has constant power
if your key is turned off there shouldn't be power to the coil.  With the key in the "on" or "run" position there should.  The coil is overheating because it's not being allowed to discharge the energy being fed into it.

 What, by the way, is a "rescue box" - pardon my ignorance, just not a familar term to me.

So i wonder if it is a problem with the switch or the module?   i'll change the switch first since i already have one of those.  then go from there.  Another forum suggested that i do the nutter bypass.  but thats their answer for everything. 

A rescue box is a device that can be placed between the battery and the distributor.  it eliminates the ECU, ignition module, and coil (in cases where the coil is seperate)  basically it is a self contained ignition computer and coil.  Its used so a vehicle that has shorted out, or has any number of other ignition problems can be "rescued" and driven back to the shop for repairs.  Usually used for Large vehicles where towing can be slow and costly.  its pretty cool.  I wish i could just bolt that in under the hood and be done with it.  ha ha. 
89 YJ - work in process
4.2L - bored 60 over - tow cam
Jasper auto trans
Still needs some things to be done before she is ready for the road/trail.

BCjeeper

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Re: Trouble shooting
« Reply #3 on: February 12, 2008, 04:34:39 pm »
Sounds like the ignition module. Drivers side fender under the coolant recovery bottle. Jim
Jim Neidrich

Rick_Bear

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Re: Trouble shooting
« Reply #4 on: February 12, 2008, 10:01:25 pm »
Not a very large photo, but here is what your ignition module looks like.
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BennyLT

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Re: Trouble shooting
« Reply #5 on: February 13, 2008, 09:22:12 am »
Not a very large photo, but here is what your ignition module looks like.


Perfect.  Thanks Rick.   The manual i have has the wiring diagrams but not good descriptions of where to find the circuits. 
89 YJ - work in process
4.2L - bored 60 over - tow cam
Jasper auto trans
Still needs some things to be done before she is ready for the road/trail.