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1998 4.0l, No spark

Old 11-05-2010, 02:18 PM
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Default 1998 4.0l, No spark

Hello,

this is my first post on this site but i have done some searching...


Here is my issue:

i recently picked up a 1998 cherokee for free, minimal rust - overall its in very good shape. However, it does not start. Apparently, it was used to boost another vehicle and hasn't started since. It was not turned on when it was used to boost the other car, the cables were directly on the battery terminals, and the cables were on the positive terminal of the other car and the grounded to the chassis of the other car.


The battery is new, but it's dead. The jeep will crank all day long with a boost, but it will not start.

Its getting fuel.

Its not getting spark. I checked for spark at the coil and the plugs, no spark at either.

The only thing i've replaced so far is the BCM (body control module), which is located behind the dash on the drivers side, sort of behind the headlight switch. I was told by someone locally that it could have been fried from the boost. it didnt work, still doesn't start and still doesn't get spark. It did change the odometer reading though lol.

I read on these forums that it could be the crank angle sensor(aka pickup coil?). Am I correct in saying that one end of this sensor is inside the distributor and the other is on the bell housing? I checked at the parts store and they only had the part that goes into the distributor.

Am i asking for the wrong part?

What else could it be?

Help me figure this out, i wanna go wheelin!
Old 11-05-2010, 02:26 PM
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I think you are looking for crank position sensor. The one you are describing is probably the cam position sensor if these are equipped.
Old 11-05-2010, 02:47 PM
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So is the cam position sensor or crank position sensor the more likely culprit?
Old 11-05-2010, 02:48 PM
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The one on the bellhousing is the crank sensor, the cam sensor is also known as the pickup coil and is in the distributor. Srart off with the crank sensor.
Old 11-05-2010, 03:04 PM
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Originally Posted by Bustedback
The one on the bellhousing is the crank sensor, the cam sensor is also known as the pickup coil and is in the distributor. Srart off with the crank sensor.
+1, anytime I've heard anything about either of the two, its always been the crank positions sensor.

And of course, it HAS to be. Its the more difficult of the two to replace.
Old 11-05-2010, 03:55 PM
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ookay, sounds fun lol.

Where is it on the bellhousing? top, bottom, left or right?

Do you need to lift the jeep to get to it?
Old 11-05-2010, 04:55 PM
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You can climb under your Jeep to get to the CPS... it is on the top of the bellhousing... sort of a PITA... especially if you have no universal joints for your ratchet... and it plugs in up by your intake manifold... If I'm not mistaken it is two 11mm bolts that hold it on... but don't quote me on that size..
Old 11-05-2010, 05:58 PM
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I believe this is the one on your Jeep. There is another CPS that has 2 bolts located in same area.

Well hope this works. The images shows a red x but I can open it. It may not open once posted. First time I get this result. Here goes. Well it works.
Attached Thumbnails 1998 4.0l, No spark-cps-4.0.jpg  

Last edited by ET JEEP; 11-05-2010 at 06:01 PM.
Old 11-05-2010, 09:36 PM
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Thanks guys, I'll report back after i change it.
Old 11-10-2010, 07:00 PM
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Okay..... so i bought a new sensor today.

took the bracket off for the shift cable. there is still no room to get to the sensor.


HOW THE %$&*^*^&* do you get to that bolt. seriosuly, i have never seen something in such a rediculous spot. a wrench won't work, it hits the bell housing bolt below the sensor........i can't get a socket on it.... WTF.

If anyone has personally replaced this sensor, what did use? pics would be very helpful.

I was excited to get this jeep running and go wheelin but, if this is any indication as to how the rest of the vehicle is built - i won't be keeping it.The most pain in the *** part i ever installed previous to this was a shift quadrant in my mustang.... that sucked but this sensor is easily 10x worse.

how the hell do you get that damn bolt out????????


sorry to rant, but damn i spent a good 1.5 hours trying to reach this thing.
Old 11-10-2010, 10:22 PM
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Sometimes pulling the front drive shaft out will give you some room to work. I used a 24" extension with a wobble socket, but mine was only a single bolt sensor.
Old 11-10-2010, 11:51 PM
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On my 97GC I moved the shifter linkage and used a long extension with a universal swivel. I also sprayed a bit of PB Blaster on it and let it set for 15 mins or so to help it break loose easier.

I know its a PITA to get to but think about this if you're gonna go off roading as many do. It's a critical sensor that will disable the vehicle if it fails or gets broken, so it's in a good place to protect it from off road damage as well as road desbris.
You'd be twice as pissed if ya broke it off with a rock or limb while 4 wheelin and got stuck out in the middle of the woods.
Old 11-11-2010, 12:19 AM
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Originally Posted by matt_101
The only thing i've replaced so far is the BCM (body control module), which is located behind the dash on the drivers side, sort of behind the headlight switch.
Do you have a p/n for that, as I may need one for my 98 4.0 and I can't find it listed anywhere.
Old 11-11-2010, 01:17 PM
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I just had the same problem with my '96. The fuel and battery gauges didn't work, the car cranked but didn't start. No spark and way less then 12v into the ignition coil. I found a blown 20A fuse in the fuse box inside the engine compartment. The wiring diagram shows that the fuse is between the battery and the ASD relay. Problem now is that the fuse now blows after about 20 minutes of running the engine. There's something else that's pulling extra current - alternator? security system?

Any ideas?
Old 11-11-2010, 04:10 PM
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Originally Posted by HenryR
I just had the same problem with my '96. The fuel and battery gauges didn't work, the car cranked but didn't start. No spark and way less then 12v into the ignition coil. I found a blown 20A fuse in the fuse box inside the engine compartment. The wiring diagram shows that the fuse is between the battery and the ASD relay. Problem now is that the fuse now blows after about 20 minutes of running the engine. There's something else that's pulling extra current - alternator? security system?

Any ideas?

That fuse is the power supply when the ASD is activated by the PCM. The fuel injectors and the O2 sensors are also on the circuit. A short in the O2 sensor seems to be a cause for that fuse blowing. Check the O2 sensor wiring.

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