90 xj I've tried everything and still NO SPARK!
08-05-2012, 08:13 PM
#31
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Year: 1990
Model: Cherokee
Engine: 4.0
Does this have an Automatic shut down relay?
Also where would you start looking for a kill switch associated with the alarm and what would it look like. Any who thanks a lot for all your input. It is much appreciatd.
Also where would you start looking for a kill switch associated with the alarm and what would it look like. Any who thanks a lot for all your input. It is much appreciatd.
08-05-2012, 08:46 PM
#32
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Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
It doesn't show in the wiring diagram what type of signal travels down the yellow wire from the ECU to ICU. You do have ignition power at the 14gauge wire on the other side of th eICU, don't you?
08-06-2012, 07:32 AM
#33
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Year: 1990
Model: Cherokee
Engine: 4.0
I do have power to the other side of the ICM. I pulled the coil and tested voltage there and it measures 12v as well.
08-06-2012, 04:13 PM
#36
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could be a micro toggle switch hidden under the Knee bolster panel .
08-06-2012, 04:13 PM
#37
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Year: 1990
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08-06-2012, 04:34 PM
#39
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Year: 1990
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08-06-2012, 06:34 PM
#41
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Engine: 4.0,2.5
Did you verify that you are getting .4-.5 ACV from the CPS, unplugged, cranking? It only takes a minute, and without that she aint gonna go. I get about 5v DC from that second, rearward yellow wire at the ICU from the ECU Btw. It will start and run with the wires to the dizzy unplugged. Unlikely your problem is there.
Also Btw, you can refer to Cruisers writings in the link in my signature.
Also Btw, you can refer to Cruisers writings in the link in my signature.
08-06-2012, 11:55 PM
#43
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Year: 1990
Model: Cherokee
Engine: 4.0
Originally Posted by Zoekat
that is correct, I do not have any spark directly from the coil.
Also, you are grounding the plugs and cranking right?
08-07-2012, 12:00 AM
#44
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Year: 1989
Model: Cherokee
Engine: 4.0l 6 cylinder
Originally Posted by Parsnip
Its either a ground out, fried ecu or cps.
Also, you are grounding the plugs and cranking right?
Sounds like cps but u may have already dealt with that
08-07-2012, 12:37 AM
#45
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Model: Cherokee
Either the ECU pulls that yellow wire up to +5 or +12V and sinks it to ground to fire the ignition, or it idles it at ground potential and puts out a +5 or +12V pulse to fire the ignition. Problem is neither signal appears to be present, the OP measured nothing at all.
If there is no signal on that yellow wire I'd think either the ECU is bad, or one of the input signals it needs to fire the ignition is missing.
Below is the 1990 ECU connector pinout.
OP has already replaced the CPS. What else here does the ECU need to fire the ignition?