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Unread 06-15-2013, 06:51 PM   #1
jjs825
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1989 YJ Wrangler 
 
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No Spark

1989 wrangler 4.2l. driving home and it died on me tried pop starting it while i was coasting to a stop and nothing. towed it home and poured some fuel in the carb and nothing. checked for spark and i have no spark so i picked up a new coil still nothing. when the key is in the run position i have power to the coil terminals but nothing after that. any suggestions would be greatly appreciated. maybe its possible the new coil i picked up is defective??? it cranks over just doesnt fire up.

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Unread 06-15-2013, 07:24 PM   #2
pete1991YJ
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Hi there and welcome to JeepForum, you've just found one of the best jeep sites anywhere!

I'm not real familiar with the older ignitions, yours the older Renix system while mine is the OBD-1 (computerized). But I do think that yours has an ignition control module, very similar to the old Ford Duraspark boxes. And they say that it burns out often. Might want to have a look at that or wait for somebody with another 1989 with the 4.2.
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Unread 06-15-2013, 07:38 PM   #3
jjs825
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I was actually looking for it today couldnt seem to locate it. i planned on starting there in the am but figured id put up a post hopeful avoid just throwing money at it. thanks for the input.
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Unread 06-15-2013, 08:14 PM   #4
dancytron
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The ICM is underneath the washer fluid and overflow coolant tanks. Take them out and it will be right there.

It could very easily be your problem.
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Unread 06-15-2013, 08:22 PM   #5
jjs825
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Quote:
Originally Posted by dancytron View Post
The ICM is underneath the washer fluid and overflow coolant tanks. Take them out and it will be right there.

It could very easily be your problem.
Awesome!! thanks alot
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Unread 06-15-2013, 08:51 PM   #6
laybackman
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I am vaguely familiar with the old Renix system. I owned an '88 Grand Cherokee years ago. It had a TDC sensor IIRC which is what we now call a crank sensor. If it goes bad you probably don't get any spark (or fuel?) either since the ECM gets no report of flywheel movement so the ECM sends no signal to the ICM which in turn won't fire the coil.

The ICM may very well be the problem. But if you swap it out and it still won't fire I would check the TDC sensor next. It is mounted on the left side of your bell housing much like the cranks sensor is nowadays.
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Unread 06-15-2013, 10:34 PM   #7
dancytron
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It doesn't have a TDC sensor or a crank sensor.
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Unread 06-15-2013, 11:28 PM   #8
jokerchief462
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OK my bad here it is the troubleshooting charts from the FSM for bot the 4.0 and 4.2. This for no spark won't start problem. 7 pages long hope you can use this and follow it. Best I got.
ign-89-4-1.jpg   ign-89-4.2-2.jpg   ign-89-4.2-3.jpg   ign-89-4.2-4.jpg   ign-89-4.2-5.jpg  

ign-89-4.2-6.jpg   ign-89-4.2-7.jpg  
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Unread 06-16-2013, 05:21 AM   #9
laybackman
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Quote:
Originally Posted by dancytron View Post
It doesn't have a TDC sensor or a crank sensor.
You're right! Maybe it was only the 2.5's. They had FI not a carb.

EDIT YET AGAIN. I think there was a 4.0 in the 1989 Jeep Cherokee Wagoneers and it had MPFI.
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Last edited by laybackman; 06-16-2013 at 05:25 AM.. Reason: not the 4.0's!!!
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Unread 06-16-2013, 12:47 PM   #10
rogerv
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Have you found anything yet ? Just out of curiosity what carb are you running ? Did you get the ICM checked to see if it's working properly ?
My last ICM lasted 10 months- switched it over to the GM style. I like $28 better than the $70 advanced auto wants.
I can send photos if you like,
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