Rockchalk

Twas the flipping Crankshaft Position Censor!!!!




Hello Cherokee Forum!!!!


I got my 20yo Cherokee Sport back! Bought it new in '96 and its gone through several family members. Most recently my retired 80yo dad has been using it when he is in town. That is, he was using it... until it started stalling on him.


So here is the situation. After a lot digging I think I have a couple problems... possibly related. Jeep has a lot of new components that I was not a part of putting in. Starter, water pump, thermostat/T housing, radiator. I also put in new IAT and TPS hoping that would cure the stalling. I recently discovered the auxiliary electric fan is not kicking on when jeep heats up. It does work when I turn on the AC.


After doing quite a but of internet searching it appears there should be two ways to activate the fan. One from the ECM when AC is turned on and another from a radiator heat sensor. This fan has only one connection... to the ECM. My first question is, is that normal for a '96? The new radiator does appear to have a plug where a temp sensor should go but there is nothing there. I took the fan out (it is factory original) and it does not appear as if there is any cut or disconnected wiring?


Second question relates to the stalling. I think due to aux fan not running the engine is running hot. It will pass mid point (110*) and get to the 130* mark or so and then stalls... just like turning the key off. It's done it consistently at that temp mark. As stated above new IAT and TPS did not solve it. I think I have a bad or going ECM but have avoided so far ponying up to get a new one. Anything else I can check before I shell out the bucks for a new one.


Battery and grounds have been checked. Fan throttle on mech fan ok. I think that covers it. Thanks in advance for help!!!

BlueRidgeMark

While I won't say that the stallking is not heat related, I will say that stalling should not happen just because of heat.

By the way, I think you mean 210 and 230...


As to the fan, mine rarely comes on, even in the summer. My AC is inoperative, so that part of the circuit doesn't work but the fan will come on normally if it does get hot. However, it usually takes a lot of crawling in bumper to bumper traffic for that to happen. I mean a LOT, and usually, up a long hill. And we've had a pretty hot summer this year.

That tells me that you probably still have cooling system problems besides your e-fan. That fan shouldn't be needed much. It comes on at something like 217, IIRC.

I'm not sure on the 96 temp sensor, so I'll leave that for others....

On the stalling, time to start checking the obvious. Any codes? Even if the CEL is not lit, you might have some codes. Many auto parts stores will read your codes for you. That would be a good place to start.

How is it running, other than the stalling?

Rockchalk

Yep... sorry 210... not 110.


It runs great. The heating to 230ish is a mystery. I haven't driven this jeep for many years and my dad has been taking care of it with an open check book. I'm not so confident in the guys that did the work though. New radiator may not be up to the job? Everything looks good though.


The aux fan from what I read should come on at 190*. Mine does not come on at all unless I turn on the AC. I put in a new temp sensor in the thermostat housing last night. I drove it some and then let it sit and idle in my driveway. Runs great and with the hood open stayed nice and cool (210*). Once I shut the hood it slowly climbed to 230* and kicked itself off.


I'm still wondering if the ECM is going. Not turning the aux fan on and then stalling. Will not restart until everything is cool again.

Martlor13

I believe the electric fan comes on at 217 degrees and with ac on.

Rockchalk

That very well may be... good to know. Regardless mine is not turning on at 217* either. Unless my gauge is bad? Still... the staling is a big problem.


Are parts shops like O'riley able to check if a computer is shot?

mikesignal

are you reading the coolant temperature with a scanner or at the dash gauge? I recently had mine in the shop and the guy told me the sending unit was toast and the gauge wasn't matching his scanner (scanner was right)

Rockchalk

Dash gauge only. I guess it's possible it's not all that hot but the big issue is when the dash gauge shows around 230* the engine turns off / stalls. Also aux fan does not come on unless I turn on the AC. Is there a fail safe that turns off the engine to protect from over heating? Still thinking the computer is going.

mikesignal

no fail safe--it will run hot until the heads warp and the motor blows up lol.....get a scanner or app for your phone and check the temps....also I had a stalling issue and it was my crank sensor--it would run fine until the jeep got hot then just die. Would restart after it cooled off.

Rockchalk

Crank sensor tomorrow then. I think that may be the last one I have left Already did air intake, temp, and throttle??? Thanks Mike.

97grand4.0

MOPAR only on that baby. If you want to see the diff put the one you take out against the new one and see how strong the magnetic pull is on your dead mopar, stronger than a new big box aftermarket store by a factor of about 3. Same with cam sensor.

mikesignal

that crank position sensor is a real PITA to get to. I got fed up with it and sent it in to the shop to get replaced. It was 96 degrees, no shade to work under, and I work outside all day too.

There are other things that can make your XJ stall out. I was getting a p0352, but that didn't show up right away. I would think a bad cap would make it stall too.Maybe PCM?

I'm no expert. Maybe someone else has some ideas before you start changing parts.

here is the thread from my issue, although I have a coil rail vs cap and wires

https://www.cherokeeforum.com/f2/p03...estart-229073/

Rockchalk

I ran the on board diagnostic trick... turn the key on six time. Holy code 11 Batman!!! Looks like it is the crank sensor. Putting in an order for a Mopar replacement and then taking jeep and part to a nearby shop. I was trying to avoid taking this thing in but as stated... its a b!tc# to get to that sensor. I think I can get it off but getting the new one on appears to be even harder. And then it won't run and I'll really be screwed.


Learning a lot! Most of all that I'm no mechanic.

NewbJeep

I had my manifolds off so replaced it just because it was right there. Still a major PITA to do. I imagine anything short of having the transmission off, it will always suck.

Rockchalk

After what shouldn't have been much trouble I was able to get my hands on the right Mopar CPS. Installed myself which was a PIA for this non mechanic guy. Reset my computer. And.... running... no stalling. Ran it for a couple hours around my neigborhood and idling in my driveway (which is when it would always stall... at idle). Looks to be cured as previously at about the 30 minute mark it would crap out.


It still seams to be running warm ( a touch over 210*) and the oil pressure looks to be on the low side. I'll look into these but happy to hopfully have the stalling cured.


Thanks to all that took the time to respond to questions!

mikesignal

Glad you got it fixed.

Mine runs around 220 at idle give or take a few degrees, sitting still for more than 5 minutes, depending on outside temps. After dealing with coolant/temperature issues I learned that the gauge is not always the best device to measure coolant temperature. You are better off looking at it on a scanner or even an IR thermometer. While driving I am at 195. If it's running high (over 225?) while sitting at idle it is most likely the clutch fan, which is cheap and easy to replace.