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slow_sprinter
User
Sep 30, 2008, 10:04 AM
Post #1 of 4
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1991 Jeep Cherokee
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1991 Jeep Cherokee 6 cyc.
KOEO no check engine light on dash
Engine will not spark. I have fuel pressure, compression, and valve train seems to be working. Noid light on injector does not light up, no spark with a spark tester either.
I am going to hook to scan tool today. What things should I be looking for? I have heard that CKP sensors go bad in these things? I have checked the wiring to the CKP sensor and found no signs of broken or burnt wires.
Thanks for any help!
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DanD
Veteran
/ Moderator
Sep 30, 2008, 10:34 AM
Post #2 of 4
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Re: 1991 Jeep Cherokee
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Can you hear the auto shut down (ASD) relay, clicking on and then off, when the ignition is first turned to the run position?
The ASD is supposed to come on for two or three seconds and then turn off, if there isn’t an ignition (rpm) signal reaching the computer. Once the engine begins to crank and produces an ignition signal the ASD is turned back on by the computer.
When the ASD is on, it supplies power to the ignition coil, alternator field circuit, fuel injectors and the O2 sensor heater. So I would be checking the ASD and whether any of the above items have power to them during that 2 or 3 second time frame?
If so then test if there is power at the items during cranking?
Dan.
Canadian "EH"
(This post was edited by DanD on Sep 30, 2008, 10:36 AM)
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slow_sprinter
User
Sep 30, 2008, 10:39 AM
Post #3 of 4
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Re: 1991 Jeep Cherokee
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Where is the ASD located? Can it be swapped out with a known good relay or is it something totally different? Can you hear it from the driver's seat or do you need to be under the hood to hear it?
Thanks! Appreciate the info.
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DanD
Veteran
/ Moderator
Sep 30, 2008, 11:20 AM
Post #4 of 4
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Re: 1991 Jeep Cherokee
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The ASD is in the power distribution centre under the hood. According to my component locator it is in position “D” of this diagram.
I’m not sure if there’s another relay you can swop out to try in there but if the numbers are the same you should be OK as long as you’re not using the fuel pump relay. Yes most time you can hear the relay click but that doesn't always mean it's working.
Dan.
Canadian "EH"
(This post was edited by DanD on Sep 30, 2008, 11:34 AM)
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