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Rockridge 4WD IS Taking Zone Offroad Suspension Lift Kits BLACK FRIDAY SPECIALS!! You asked, we deliver!Rough Country Lift Kits and Parts!

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Unread 11-01-2012, 11:56 PM   #1
grandlakejeeper
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Join Date: Nov 2001
Posts: 13
No Spark- and Nutter Bypass

89 YJ with 4.2; 130K miles. Just died this week; cranks with good fuel and battery but just no spark at either plugs or top of distributor. Coil ohms withing specs. Power at coil is 12 V but only 6V at top of distributor. Gauges horn everything seems to work with the exception of the ignition key buzzer that did before this; not sure if relevant.

My question is whether the ignition control module is the likely culprit even though engine has been Nuttered. I hate to undo the splices to take it to the parts shop for testing if any other cause is more likely.

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89 Wrangler; 4.2 13.5 x 33 SSTs; Ramsey Winch
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Unread 11-02-2012, 08:27 AM   #2
Mark05059
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1989 YJ Wrangler 
 
Join Date: Mar 2009
Location: quechee Vermont
Posts: 4,351
yes your looking at an ICM change.
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1998 ZJ 5.2 Auto

1989 Wrangler Black Bone Stock 2.5l 5spd
/l , [____],
|---L--[]lllllll[]-
()_) ()_)==O=)_)
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Unread 11-02-2012, 09:28 AM   #3
90DesertTanYJ
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1990 YJ Wrangler 
 
Join Date: Jun 2012
Location: Jacksonville, FL
Posts: 750
Definitely sounds like the ICM. If you still have the original wire harness connector, you can repin it and restore it. I went ahead and took the connector apart and removed the old wire and soldered the harness wires back in. It was kinda a PITA but now everything is plug and play again. I also made the new purple and orance wires long enough to mount the ICM higher up on my fender. Its a lot better than tucked under the coolant and washer bottles.

Also since the ECM is now doing nothing, you can take that out as well if your feeling froggy
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Unread 11-02-2012, 11:25 AM   #4
grandlakejeeper
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Join Date: Nov 2001
Posts: 13
ICM and ECM

Thanks. Bought a new ICM today and plan to install this evening. The last post, however, has me puzzled. I have read so many post overs the last two days about coils, distributors, ICMs, and ECMs, SSIs, and MPUs. If the ICM is the part below the coolant reservoir that "controls" spark even after a Nutter bypass, then I assume the ECU is the part on the passenger side above the heater that no longer has any purpose. It is unlikely I will take time to remove it but it would be nice to know whether I need to even think about it in the future if I have another problem. Thanks for the help.
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89 Wrangler; 4.2 13.5 x 33 SSTs; Ramsey Winch
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Unread 11-02-2012, 04:01 PM   #5
Mark05059
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1989 YJ Wrangler 
 
Join Date: Mar 2009
Location: quechee Vermont
Posts: 4,351
yes the ecm above the heater is no longer required. It can stay there or you can remove it. Makes no difference.
__________________
1998 ZJ 5.2 Auto

1989 Wrangler Black Bone Stock 2.5l 5spd
/l , [____],
|---L--[]lllllll[]-
()_) ()_)==O=)_)
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Unread 11-04-2012, 07:14 AM   #6
grandlakejeeper
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Join Date: Nov 2001
Posts: 13
Installed ICM. Runs like a top. I started having starting trouble last weekend so I guess it was going bad. I know we don't like putting out money except for the fun mods but suggest that if your YJ is still running the original ICM, you might want to replace it. Cheap insurance to avoid getting stuck on the trail or a highway. I was lucky - mine died while pulling into my driveway. Same thing with a starter if you hear if starting to slow down on a start and you know the battery is fully charged. Thanks to those who responded.
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89 Wrangler; 4.2 13.5 x 33 SSTs; Ramsey Winch
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