Working on a ’99 Grand Cherokee. I have been troubleshooting a no crank, and I have verified that the battery is fine. It starts once in a blue moon on its own. I have checked the starter, relays, fuses, and switches. I replaced the ignition switch since it was old, and it was very hit or miss. I have also cleaned the battery terminals, grounds, and posts. Since replacing the switch, I am getting the full 12 V on the yellow wire when the key is turned to START; however, I am not seeing any voltage across fuse 31, labeled Starter Relay. I just wanted to double-check that I should indeed be getting 12 V there when the key is turned. Looking at the wiring diagrams, it seems like the ignition signal goes to the junction box, then runs to the fuse, and there is no other circuit that interferes with this. I have been looking everywhere for confirmation but have yet to find anything. All help would be appreciated!
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brandishing_bob
No Start/No Crank
Working on a ’99 Grand Cherokee. I have been troubleshooting a no crank, and I have verified that the battery is fine. It starts once in a blue moon on its own. I have checked the starter, relays, fuses, and switches. I replaced the ignition switch since it was old, and it was very hit or miss. I have also cleaned the battery terminals, grounds, and posts. Since replacing the switch, I am getting the full 12 V on the yellow wire when the key is turned to START; however, I am not seeing any voltage across fuse 31, labeled Starter Relay. I just wanted to double-check that I should indeed be getting 12 V there when the key is turned. Looking at the wiring diagrams, it seems like the ignition signal goes to the junction box, then runs to the fuse, and there is no other circuit that interferes with this. I have been looking everywhere for confirmation but have yet to find anything. All help would be appreciated!
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Take a look at this it might help
Now beside that with my WJ i had this problem, no start one day than would start and be fine for couple of day and than no signs of life again, everything turning on just no turnover.
In the end it was the starter probably the built in solenoid….one day got mad picked up little hammer banged on the starter and it turned on…..for 3 weeks I knew whenever stopping somewhere 2 seconds reached under the starter couple of slap turned right on, till I change it and everything back to normal.
I hope it helps for now if I find anything else I’ll post it.
Now beside that with my WJ i had this problem, no start one day than would start and be fine for couple of day and than no signs of life again, everything turning on just no turnover.
In the end it was the starter probably the built in solenoid….one day got mad picked up little hammer banged on the starter and it turned on…..for 3 weeks I knew whenever stopping somewhere 2 seconds reached under the starter couple of slap turned right on, till I change it and everything back to normal.
I hope it helps for now if I find anything else I’ll post it.
Now that i think about it take a look at the neural safety switch too! Had that problem too! Mine was just a cut wire! Here is a reference location video!
Just a little update. I can jumper pins 30 and 87 on the relay with the key on run to start the jeep. Checking more in depth, I see that when the key is turned to START, with the meter on pin 86 of the relay and the other end on ground, I get 12V. For pin 88 I get no continuity on ground anywhere. Going to look into this further!
Which engine do you have? I believe PCM provides ground to activate the relay so the ground path is not always available. The PCM requires the trans in Park or Neutral before it completes ground. Neutral Safety Switch (4.0) or Transmission Range Selector (4.7) are common failure points. NSS is an easier fix, TRS is harder.
Try starting in Neutral, wiggle the gear selector, crawl under and look for broken wires going to transmission...
Try starting in Neutral, wiggle the gear selector, crawl under and look for broken wires going to transmission...
any luck on figuring this out? i am having the same issue, i have full power with key in on position but it will not crank over no matter what. i tried bypassing the relay by jumping the starter that way but it still will not crank, tried manually jumping the starter with a screwdriver with the key in the runs position to no avail, verified the starter is good (also replaced with new one), verified fuses are good, and verified the neutral safety switch also appears to be working correctly.
blueboarwf, the accepted convention is to start a new thread, and possibly post a link to a similar thread (like this one) when soliciting a question. Personally, when I see the original post was really old, I almost never click on the thread to even see if I can offer potentially useful advice. Just saying.
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