It never ends, replaced battery grounds now no start
03-02-2016, 10:46 AM
#61
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Year: 1999
Model: Cherokee
Engine: 4.0
I'm sure a PCM driver circuit shouldn't be 12 volts, but this vehicle has "live Grounds". I've never tested the coil driver voltage but plenty of sensor ground circuits, which runs around .010 to .020 volts (RUN).
Some relay control coil ground circuit drivers I've tested showed .01 to .02 volts with key to RUN (usually the difference between the CCD Bus (+) and (-) voltages.
As a sample, try pulling the connector off #1 fuel injector and see if the PCM driver circuit wire shows 12 volts (Ign. RUN). See diagram below for the #1 injector wires.
Some relay control coil ground circuit drivers I've tested showed .01 to .02 volts with key to RUN (usually the difference between the CCD Bus (+) and (-) voltages.
As a sample, try pulling the connector off #1 fuel injector and see if the PCM driver circuit wire shows 12 volts (Ign. RUN). See diagram below for the #1 injector wires.
03-02-2016, 12:13 PM
#62
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Year: 1999
Model: Cherokee
Took another reading at the coil connector. Key in run position. Grey .009v. Green .004v. Could that be right?
This is one of many reasons why I try to double check myself. Doing this. Without the benefit of another set of hands, in the dark, and in the elements makes things difficult at best.
When cranked, it wants to start but still no joy...
This is one of many reasons why I try to double check myself. Doing this. Without the benefit of another set of hands, in the dark, and in the elements makes things difficult at best.
When cranked, it wants to start but still no joy...
Last edited by Crow Horse; 03-02-2016 at 12:16 PM.
03-02-2016, 07:49 PM
#67
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Year: 1999
Model: Cherokee
On a hunch (sometimes that's all I have), I replaced the cam position sensor and the crank position sensor (Mopar). No small task, 30-40 mph winds and temps ranged between 20-29. Not fun....
Fired right up. I was really surprised!
Thanks Ken for all your help. I learned a great deal during the ordeal and I really appreciate you spending the time to walk me through the testing....
Oddly enough, the cps tested good however maybe the problem was in the connector. Not sure, but it runs now!
Fired right up. I was really surprised!
Thanks Ken for all your help. I learned a great deal during the ordeal and I really appreciate you spending the time to walk me through the testing....
Oddly enough, the cps tested good however maybe the problem was in the connector. Not sure, but it runs now!
03-03-2016, 05:35 PM
#72
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Year: 1999
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Thanks guys. I couldn't have done it without your help......
My hunch was based on previous experiences with a failing cps. It behaved similarly and I took a gamble. I replaced the cam position sensor as well only because it was from Advanced Auto and they are notorious for premature failure. Now its all OEM Mopar. Cost was $204 for both. New guy at the parts counter and I wasn't able to get the discount they usually throw my way. Pricey, but I'm so glad to get my XJ back on the road. It was a real hardship for me.
Again, thank you, thank you, thank you, thank you for everyone's help......
BTW, I did replace my positive + (battery to starter, battery to PDC) cables and used the military type of battery terminals....
And yes, it still starts, LOL
My hunch was based on previous experiences with a failing cps. It behaved similarly and I took a gamble. I replaced the cam position sensor as well only because it was from Advanced Auto and they are notorious for premature failure. Now its all OEM Mopar. Cost was $204 for both. New guy at the parts counter and I wasn't able to get the discount they usually throw my way. Pricey, but I'm so glad to get my XJ back on the road. It was a real hardship for me.
Again, thank you, thank you, thank you, thank you for everyone's help......
BTW, I did replace my positive + (battery to starter, battery to PDC) cables and used the military type of battery terminals....
And yes, it still starts, LOL
Last edited by Crow Horse; 03-03-2016 at 05:40 PM.
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