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HHalverson 06-07-2013 03:40 PM

89 Jeep no crank
Hi all, A friend of mine has a 89 Wrangler with a 4.2 and Manual trans. The issues started about a year ago when. Whenever you turned on the Headlights the engine would sputter out, Backfire and die But, if you turned on the heater then it would smooth out and run.

Now the engine wont crank at all. I checked the battery which is good. You can jump across the starter relay and the engine will turn over. When you turn the key the seat belt warning light comes on. When you turn it the the cranking position the blinker dash indicator comes on. No fuel pump. I put a test light on the fuse in the fuse box. With the switch off the light is off. When you turn the ignition on the test light, lights up. So the ignition switch is good. I have checked all of the grounds in the engine compartment and they have been cleaned.

I pulled the ICM and took it to NAPA and it tested good. I have no clue where to go next. Is there any way to test the MCU with just a test light and a volt / ammeter?
Any ideas would be much appreciated. Thanks,

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