# 96 Jeep Grand Cherokee won't start



## wrangler

Bad ignition or relay? It shouldn't affect the windows if it is the pump, in fact, shouldn't start at all if the pump is out. Google the problem and see if there isn't a jeep site. My gf's car had an odd problem where it would not start when all else was fine... after searching I found it was an anti-theft problem where the sensor would not recognize the key and you had to let it sit with the ignition on for 10 mins then try again. TG for the internet!


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## bigburb

I had this problem with my 98 jeep I6, wound up getting a new computer from the dealer to fix it. the solder joints inside the computer go bad over time, in my case it would kill the power to all the engine's sensors at the same time and die. Another time it wouldn't start it wasn't supplying power to the starter relay. try removing and cleaning the harnesses that go into the computer with some electrical cleaner, see how it does after that.


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## gotboost

Sounds like the vec thinks the alarm is on thats about the right time frame to shut down the fuel pump relay,hold your hand on the relay while someone eles starts the vec as the key is turned to start the relay will power up which you can feel if it shuts off after a couple seconds and you feel the relay click,you have an alarm problem,which could be in the pcm


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## bigburb

also check the ASD relay to see if its working, it'll be labeled in the fuse box. it and all the other relays are the same so you can switch it with the wiper relay or something to see if it works.


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## shanekw1

Check your fuel filter.


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## DIYtestdummy

If you could tell me which engine, trans, and trim package you have I could probably help. Sounds to me like a Crank Position Sensor, starter kill module, fuel pump, relay for the previous 2, ignition switch, air bag sensor, computer or trans shift computer if automatic,...

Been working on and modifying Jeeps the past 13 years... :jester:

Oh, and you could send her to my "junk yard!"


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## KHouse75

I have a 98.

Some things I can think of:

Key without resistor.
Bad ASD Relay.
Screw for PCM cover shorting out the circuit board (Came across this while searching for another problem a few years ago)
Alarm system is activated.


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## Bigfoot

I'm going to go out on a limb here and say your Idle air controller is sticking. It's bypass air for when the throttle plate is closed on the throttle body. The computer adjusts it so you have the minimum air needed at start up or when the motor is idling or anytime the throttle plate is closed.
May also be tied in with what appears to be an intermittent electrical problem. The idle air controller needs all the juice it can get to function properly.
Before I'd replace the IAC, I'd try squirting some oil into the opening, sometimes this is enough to loosen the crud and get it to working properly again.
The electric problem may be the power supply for the PDC (power distribution center/fuse box under the hood) the nut holding the cable ring (main power source) to the common power bus has been know to come loose. Or just plan old loose or dirty connections for the battery and engine block ground.


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## handiyman

*96 Jeep Cherokee Sport I-6 4WD Auto*



DIYtestdummy said:


> If you could tell me which engine, trans, and trim package you have I could probably help. Sounds to me like a Crank Position Sensor, starter kill module, fuel pump, relay for the previous 2, ignition switch, air bag sensor, computer or trans shift computer if automatic,...
> 
> Been working on and modifying Jeeps the past 13 years... :jester:
> 
> Oh, and you could send her to my "junk yard!"


 Here Goes (son's Jeep) Son turned key and it went all the way forward. No start. First move - call dad. Dad (me) spends half day discovering what anti-tamper torx bits are. For a mere C-note, bought and replaced both ignition switch and lock cylinder. Turning key was very tight and mushy, but started right up. Son drove it for a day (has a pool maintenance route). Had several starts he says were "weak starts." Day 2:jeep won't start. First move - call dad. Took starter switch back and got 2nd new one. Installed, turned key (again a little tight and mushy) Jeep started right up. Running fine. Turned key off. Turned key back on and nothing. Dead again. This is day 5. Both of us can now remove/install ignition switch blindfolded with boxing gloves on at record speeds. Several times he has gotten it to start, and it runs for several seconds and dies. Can't bring it to your junk yard in Arizona unless I can get it to start and run in Texas.


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## MALCO.New.York

Fuel Pump????


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## bigburb

only a bad computer could be that flaky. same thing with my jeep, there didn't seem to be a pattern to it, as soon as i replaced something it would start and run great for a while but as soon as i handed the keys to my wife she would get stranded somewhere. 

you might want to try replacing your CPS sensor (go with factory sensor only), but if its not throwing any codes for this then more than likely its your computer. 

go with a dealer remanufactured computer only! i bought one from a company called auto computer exchange because it was cheaper but went through 2 defective computers before i went to the dealer.


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## jordy3738

I had a 93 jeep that used to go through spark plugs like crazy. It seamed like every six to eight months I had to but a new set in.

Every time there would be a hesitation or the thing would start running a little rough, I'd always start with changing the plugs.


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## Bigfoot

handiyman said:


> Here Goes (son's Jeep) Son turned key and it went all the way forward. No start. First move - call dad. Dad (me) spends half day discovering what anti-tamper torx bits are. For a mere C-note, bought and replaced both ignition switch and lock cylinder. Turning key was very tight and mushy, but started right up. Son drove it for a day (has a pool maintenance route). Had several starts he says were "weak starts." Day 2:jeep won't start. First move - call dad. Took starter switch back and got 2nd new one. Installed, turned key (again a little tight and mushy) Jeep started right up. Running fine. Turned key off. Turned key back on and nothing. Dead again. This is day 5. Both of us can now remove/install ignition switch blindfolded with boxing gloves on at record speeds. Several times he has gotten it to start, and it runs for several seconds and dies. Can't bring it to your junk yard in Arizona unless I can get it to start and run in Texas.


 A few basics, the ignition switch activates various relays. As soon as the key is turned, the computer closes the fuel pump relay (for a few seconds) to prime the injector rails and closes the ASD relay supplying current to the ignition coil and alternator (among other things). As soon as it starts and the computer gets a pulse signal from the crank position sensor and the sync sensor, it closes the fuel pump relay again, pressurizing the fuel rail, then signals (pulses) the ignition coil to make spark.
If the crank position sensor is bad it will usually supply no fuel or spark. Though if the crank position sensor is weak or partially shorted, function can be iffy.
Export models have modules that interrupt the ASD (auto shut down) circuit. It works with the remote door lock opener as an anti-theft device.
You have to figure out if you are getting fuel, getting spark and getting air. The idle air controller is a piston controlled by the computer that bypasses air around the throttle plate, during start and at idle when the throttle plate is closed (your foot is off the gas pedal).
I've had my 96 start intermittently and run like crap (barely run) when it did start. It turned out to be short in the crank position sensor.
I also had it do just about the same, whne there was a bad connection at the module, worked by the key fob door opener. The bad conection at the door opener/anti-theft interruptor was for the ASD relay.
I've also had my IAC stick closed and the motor would often not start and if it did start would stall almost immediately. A little cleaning and spray oil lubrication cured that.
I've also heard a bad sync sensor, will do the same thing or at least much the same results, though I've never had that problem myself.
Could be other things, but these are a few of the more common. If it is a fuel issue, there is a pressure fitting on the fuel rail, where the pressure can be measured. Could be as simple as a bad coil to cap cable that is partially shorted or open, or a really badly worn distributor cap.
NAXJA.org has a bunch of info for most anything Cherokee related. Using the search function will likely turn up enough reading for weeks. Alldata.com has most all of the tests you can do, locations for most all of the sensors and wiring diagrams for a fee. Worth it in my oppinion. PM me for some PDF. info that may be helpful.


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## DIYtestdummy

Bigfoot said:


> A few basics, the ignition switch activates various relays. As soon as the key is turned, the computer closes the fuel pump relay (for a few seconds) to prime the injector rails and closes the ASD relay supplying current to the ignition coil and alternator (among other things). As soon as it starts and the computer gets a pulse signal from the crank position sensor and the sync sensor, it closes the fuel pump relay again, pressurizing the fuel rail, then signals (pulses) the ignition coil to make spark.
> If the crank position sensor is bad it will usually supply no fuel or spark. Though if the crank position sensor is weak or partially shorted, function can be iffy.
> Export models have modules that interrupt the ASD (auto shut down) circuit. It works with the remote door lock opener as an anti-theft device.
> You have to figure out if you are getting fuel, getting spark and getting air. The idle air controller is a piston controlled by the computer that bypasses air around the throttle plate, during start and at idle when the throttle plate is closed (your foot is off the gas pedal).
> I've had my 96 start intermittently and run like crap (barely run) when it did start. It turned out to be short in the crank position sensor.
> I also had it do just about the same, whne there was a bad connection at the module, worked by the key fob door opener. The bad conection at the door opener/anti-theft interruptor was for the ASD relay.
> I've also had my IAC stick closed and the motor would often not start and if it did start would stall almost immediately. A little cleaning and spray oil lubrication cured that.
> I've also heard a bad sync sensor, will do the same thing or at least much the same results, though I've never had that problem myself.
> Could be other things, but these are a few of the more common. If it is a fuel issue, there is a pressure fitting on the fuel rail, where the pressure can be measured. Could be as simple as a bad coil to cap cable that is partially shorted or open, or a really badly worn distributor cap.
> NAXJA.org has a bunch of info for most anything Cherokee related. Using the search function will likely turn up enough reading for weeks. Alldata.com has most all of the tests you can do, locations for most all of the sensors and wiring diagrams for a fee. Worth it in my oppinion. PM me for some PDF. info that may be helpful.



That's pretty much what I posted a week ago, but I must've hit the wrong button and sent it into cyberspace. IAC will stick (like mine is now), but I never heard of it making the engine stall. It WILL make the idle high if it's bad. If your intake is clogged - maybe, but that's not the IAC's fault. Now the TPS will make it stall, but it would have gotten progressively worse, not just all of a sudden and it would run like crap if it did start. Seafoam it! Good stuff.

I'm going with CPS still if it's still that flaky. Could also be the NSS switch if it's an automatic. Starter solenoid could be bad too - get the starter/solenoid combo; it's cheaper. Electronics are funky and you'll probably not find the fix right away, so start cheap. Could be a shorted start wire to the fusible link - aaah, that one drove me nuts for the longest time!

NAXJA.com, Jeepsunlimited.com (notsogreat these days), and there are many more good ones that I don't visit since I have a new money pit that costs more and takes most of my time.

:whistling2:


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