Replaced crank position sensor. Jeep Cherokee still won't start.

Turbodan

Turbodan

Forum Member
Saturday I was driving home and the check engine light came on. Got home and parked it. 3 hours later got in it and would not start. Borrowed a scan tool and got a Crank sensor error. I disconnected the battery and then climbed underneath to install a new sensor. Reconnected the battery which cleared the engine light. Tried starting it. Would not fire up. Does not seem to be getting spark from the coil. No check engine lights have come up. What should I do/replace next? This is on a 1999 with a 4.0. Is there fuses or relay fuses that might cause this.
 
first thing you should do is stop creating new threads for every question, haha

how long was the battery disconnected? if less than 30 minutes it could still retain memory.

next, check for voltage at the sensor (harness side). If present, check for voltage which the sensor is connected. There is a chance you got a bad sensor. its happened to me before.

if no voltage is present trace wire and verify its good all the way back to the ecu. If still no voltage, check for voltage at the ecu itself. if not present, replace the ecu.

also, check for input voltage/spark at the coil. as I asked in the first thread, what condition is the coil in?
 
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times like this make me glad my 4.0 is an indestructible 1994. 175k and still runs like new
 
avbcon12 said:
same engine other than a revised (better) intake manifold...
Click to expand...
theyve got worse pistons which are known to brake the shirts off and grenade the motor as well as the coil on plug setup, which when it works is awesome, but ive seen alot of people have problems with the higher mileage ones. i prefer the distributor, IMO, you dont need COP on a motor with a 5k redline
 
Turned out to be the pickup coil under the distibutor cap. The little magnet on the unit fell off. Ended up changing the coil also.
 
cjmatt said:
theyve got worse pistons which are known to brake the shirts off and grenade the motor as well as the coil on plug setup, which when it works is awesome, but ive seen alot of people have problems with the higher mileage ones. i prefer the distributor, IMO, you dont need COP on a motor with a 5k redline
Click to expand...

COP doesnt start until 2000.
1995: new cylinder head (better flowing than previous models, upped from 178hp to 190)
1996: new block, better webbing, stronger and has a stud girdle for crank.
1998: new cylinder head again, not as good as previous years, flows less for emissions.
2000: some distributorless
2001: all distributorless

basically, you want a 95-97 head with a 96-01 block, or just a 96/97 jeep. ignition is really a toss up. ive had many jeeps with both and they seem the same to me. although its a hell of a lot more $$ to replace the COP if it fails than a coil or wires.



Turbodan said:
Turned out to be the pickup coil under the distibutor cap. The little magnet on the unit fell off. Ended up changing the coil also.
Click to expand...

Cool! glad you figured it out
 
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avbcon12 said:
COP doesnt start until 2000.
1995: new cylinder head (better flowing than previous models, upped from 178hp to 190)
1996: new block, better webbing, stronger and has a stud girdle for crank.
1998: new cylinder head again, not as good as previous years, flows less for emissions.
2000: some distributorless
2001: all distributorless





Cool! glad you figured it out
Click to expand...
what years did they switch pistons. ive heard numerous stories of guys dropping piston skirts on 97+ 4.0s never on older ones
 
hmm, I dont know that one.


I also forgot in 99+ they made the intake better flowing for the changes in the cam and head so you want a 99+ intake manifold and cam.
 
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