1998 Jeep Grand Cherokee 98 Jeep Grand Cherokee wont start

Tiny
IHATEJEEPS19
  • MEMBER
  • 1998 JEEP GRAND CHEROKEE
  • 5.2L
  • V8
  • 4WD
  • AUTOMATIC
  • 187,000 MILES
Got the jeep about 5 months ago, it ran fine, had a couple of problems (coolant sensor is bad, had to replace the fuel pump and a tranny line). The day after the fuel pump was fixed, I began having problems with it not starting, it would crank but not start up. We replaced the crankshaft position sensor thinking that would fix the problem. It fixed it for about 3 weeks then I started having the same exact problem. My boyfriend would shake the wiring harnesses and unplug the plugs that connect into the computer then plug them back in. It worked about 4 times then it wouldnt start up, no matter how much he shook the wiring harnesses and unplugged the plugs. He checked the computer but all it read was that the coolant sensor was bad. Im completely at a loss. Someone help please!
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Wednesday, August 19th, 2015 AT 1:48 PM

3 Replies

Tiny
CARADIODOC
  • EXPERT
First you have to understand what you're doing by disconnecting stuff. Any time the battery or Engine Computer are disconnected, the computer loses its memory. The fuel metering data will be rebuilt as soon as you start driving, but not "minimum throttle". Until that is relearned, the computer won't know when it has to be in control of idle speed. The engine may not start or stay running unless you hold the accelerator pedal down 1/4", you won't get the nice idle flare-up to 1500 rpm at start-up, and it will tend to stall at stop signs. To meet the conditions needed for the relearn to take place, drive at highway speed with the engine warmed up, then coast for at least seven seconds without touching the pedals.

Anything that removes power from the Engine Computer also erases any diagnostic fault codes, so you're losing that valuable information. Some fault codes related to no-starts will not set just by cranking the engine. They set while a stalling engine is coasting to a stop. That means the computer may have detected a problem and set a fault code directing you to the circuit that needed further diagnosis, but you erased the codes by disconnecting the battery.
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Wednesday, August 19th, 2015 AT 3:49 PM
Tiny
JETSFAN44
  • MEMBER
I had the same thing for months. Replace the computer. Advance auto 250.00. Mine has been three years and no problems after replacing it.
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Friday, September 4th, 2015 AT 8:06 AM
Tiny
CARADIODOC
  • EXPERT
If shaking the wiring affects the problem, how will replacing the computer solve that?
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Sunday, September 6th, 2015 AT 8:04 PM

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