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#1 10-17-2008 01:05:07

grub
Newbie
Registered: 10-05-2008
Posts: 10

Re: no spark on 93 cherokee

I need some input here, ive got a 93 cherokee that doesnt want to
start, it will turn over but no spark. i replaced spark plugs, wires,
rotor, and cap. I have the best testing tool for parts available to
deduce the problem. I took the coil off of the 93 and put it on my 95
and it fired right up. I took the brain out and tested it on the 95
and the same result. Has anyone out there seen or heard of this problem
before. any help would be appreciated. and, yes I checked all the fuses
and relays the same way.

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10-17-2008 01:05:07

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Re: no spark on 93 cherokee

#2 10-17-2008 01:06:39

stellarxj
Rookie
Registered: 10-05-2008
Posts: 73

Re: no spark on 93 cherokee

You have eliminated everything except the pickup module on the base plate.  I just replaced the one in the kids Cherokee.  Since you have a test mule, swap them and see what happens. If it doesn't work, you won't get the coil not to go to ground and hens no spark.

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#3 10-21-2008 22:55:06

evad
Enthusiast
Registered: 10-05-2008
Posts: 240

Re: no spark on 93 cherokee

If the '93 has a flywheel position sensor (TDC sensor) this is definitely one area to look at. 
Some engines also have a camshaft sensor, but don't know if the Jeeps did.
These sensors often become intermittent before failing completely.  In some cases dirt accumulates on them, preventing them to sense properly, sometimes it is a dirty connector issue.  I had one fail after my tranny was replaced.  Found out the mechanic reinstalled the sensor too close to the flywheel and the sensor end got abraded by the flywheel.


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#4 10-22-2008 15:04:50

thomas
Helper
Registered: 10-22-2008
Posts: 15

Re: no spark on 93 cherokee

where is the pickup module located, as I have no book it is hard for me to locate some parts on the motor or engine compartment

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10-22-2008 15:04:50

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Re: no spark on 93 cherokee

#5 10-22-2008 22:44:24

stellarxj
Rookie
Registered: 10-05-2008
Posts: 73

Re: no spark on 93 cherokee

OK, I got the book out.  You have a distributer camshaft sensor, that's the thingy I called a pickup module.  This is located in the base of the distributer inside the cap.  If you take the distributer cap off you will see that the wires from your coil attach to a piece of bakelite that is held down by two screws I think.  Anyway, this piece of bakelite that the wires attach to is the module I think you need to check out.  You also have a crankshaft position sensor on the 93-94 models.  Let's leave this alone for a while.  The crankshaft position sensor is there for the fuel injection system.  It tells the ECM where to start the fuel injection sequence each time the crankshaft rotates.  Unless you have a distributerless ignition, which you don't, the CPS only affects the fuel distribution, not the spark ignition.

So what if you put it on your test mule, and it works?  Find a test light or volt meter and make sure you have power to the coil etc.

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#6 10-23-2008 12:16:01

grub
Newbie
Registered: 10-05-2008
Posts: 10

Re: no spark on 93 cherokee

it was the angle crank sensor. located on the bell housing of the tranny about 20 degrees driver side on some models or on the front of the motor by the harmonic balancer on others. took the one off the test mule installed it the downed chariot and it cranked right up. my local auto parts store had 3 in stock. about 60 bucks so i left my mule unit in the downed one and installed the new one in the mule. thanks for all the help.

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#7 10-23-2008 13:30:31

howard
Helper
Registered: 10-05-2008
Posts: 24

Re: no spark on 93 cherokee

Makes sense to me, if the ecm doesn't know where TDC is it can't figure out when to fire.

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