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Camshaft Position Sensor PROBLEM ???

49K views 10 replies 5 participants last post by  02tjsport 
#1 · (Edited)
So peroidodicly on my 98 tj 4.0 I have been getting code p340 for the camshaft sensor, I have been disconnectiong the battery to clear the code,
Today I took the distributer cap off and took the camshaft position sensor off and saw there was some metal flakes on the contacts (sensor part) I then blew it out with a compressor, reinstalled it , go to start the jeep and it will just crank for a couple seconds then the Check Engine lights comes on and it wont start but will keep cranking


is the camshaft position sensor toast or could it be something else?

I dont have a code reader to see what code is causing the light to come on
 
#2 ·
gtospeeding said:
So peroidodicly I have been getting code p340 for the camshaft sensor, I have been disconnectiong the battery to clear the code,
Today I took the distributer cap off and took the camshaft position sensor off and saw there was some metal flakes on the contacts (sensor part) I then blew it out with a compressor, reinstalled it , go to start the jeep and it will just crank for a couple seconds then the Check Engine lights comes on and wont start. I disconnected the battery and the same thing happens when I try and start it

is the camshaft position sensor toast or could it be something else?
its almost cranking like the coil is bad
I dont have a code reader

98 tj 4.0
I have an '02 and i get the same error code every couple of months... I have just learned to ignore it.

P0340 does not mean that the CMP is bad, its just means that the PCM did not receive a signal from it. P0341 means 'Problem with voltage signal from CMP'...

So i'm guessing that P340 is ambiguous at best. I am still trying to figure this out...

Not sure about your model, since the 02 does not have a distributor, but make sure if you mess with the CMP assembly that you do not lose the CMP sensor-camshaft relationship or the engine will not start. the injectors will open at the wrong times...
 
#4 ·
FYI, if the jeep is not getting a signal from the Crank position sensor or the Cam Position sensor, it will shut down the fuel system while cranking.

Wrangler2002, you may want to take off your cam sensor and check it out. I got the same code on mine a few months back and after it started shutting off the fuel system sporadicly on the interstate. Then a week later, when i needed to be somewhere, it went way bad and wouldnt start back up at a gas station.

I took the sensor off and it was TOAST, nothing left inside of it. I replaced the part, still nothing.

It ended up being the Oil Pump Driveshaft Gear (the metal peice that the sensor sits atop of.

Just some food for thought...could be the same thing on the 98, since i think the distributor sits atop of the same type of thing.
 
#6 ·
gtospeeding said:
BTW I have a distrubuter cap, not a coilpack
Right, but the cam sensor sits inside the distributor somewhere if i remember correctly and the shaft that the distributor is on is connected to the oil pump the same way the 02+ is.
 
#7 ·
The crankshaft position sensor is on the back of the engine driver side of the block. The hall effect sensor is inside the distributor. I had a friend with a 99 cherokee with the same setup. We farted around with that thing for 8 hours trying to fix a crank but not start symptom. He had the same symptoms. it had trouble starting one day then it ran fine then it just quit. We replaced the crankshaft position sensor which is the magnetic sensor on the back of the engine that senses the position of the flywheel on both an automatic and manual 4.0l prior to 2000. This had no effect on the problem. So after posting in the cherokee forum, I found that the hall effect sensor, or CKP sensor which is the one that you are referring to inside the distributor, was bad. That sensor will also cause a crank but no start. It may look tattered or it may look brand new, but you dont know if it is bad until you replace it. Go to the junkyard or a used auto parts place and get a used one. HTH

My CPS/CKP thread http://www.jeepforum.com/forum/showthread.php?t=423208
 
#8 ·
I was checking out the cam sensor and from what I saw it has paint worn off it where it makes "contact" in the distributer.

tjwrangler89 said:
The crankshaft position sensor is on the back of the engine driver side of the block. The hall effect sensor is inside the distributor. I had a friend with a 99 cherokee with the same setup. We farted around with that thing for 8 hours trying to fix a crank but not start symptom. He had the same symptoms. it had trouble starting one day then it ran fine then it just quit. We replaced the crankshaft position sensor which is the magnetic sensor on the back of the engine that senses the position of the flywheel on both an automatic and manual 4.0l prior to 2000. This had no effect on the problem. So after posting in the cherokee forum, I found that the hall effect sensor, or CKP sensor which is the one that you are referring to inside the distributor, was bad. That sensor will also cause a crank but no start. It may look tattered or it may look brand new, but you dont know if it is bad until you replace it. Go to the junkyard or a used auto parts place and get a used one. HTH

My CPS/CKP thread http://www.jeepforum.com/forum/showthread.php?t=423208
 
#9 ·
this is not a "camshaft sensor"

this sensor, inside the lower part of the distributor, is MOPAR's way of sending distributor position to the CPU before newer technology came along.

The best way to check for this sensor malfunctioning is this:

wait till it quits on you.

try to start it....still no start.

remove battery cable. wait 10 seconds. try to crank and restart.

if still NO start,

then pull codes. use the ignition key trick. if it IS the distributor "hall effect pickup sensor" then you will throw a code 11 first, then possibly 12 (normal) and then 55 (normal)

there are two of these pickup sensors on the jeeps, up until distributorless ignition, one on the bellhousing/transmission, known as the CKP and CPS sensors. they usually go out when it's hot and underhood heat is building up (traffic, etc) and then re-start when things cool down.

the only way to pull a code 11 (no distributor synch signal) is with disconnecting the battery and then cranking, and no start. the computer will store a code 11 since it has never seen a signal- since the battery was disconnected.

I would do this prior to purchasing a new CKP sensor. most often it is the bellhousing pickup that goes first, but dying WHILE driving is distributor pickup in my 22 years MOPAR wrenching. I've had 2 die on me (dodge daytona turbo) and shelby SS. those 1980's technology is the same in our jeeps from 1990-onward!! (prior was RENIX)
 
#11 ·
Yea that my bad, on the 02 (or whatever year the tj went distributorless) it is a camshaft position sensor.

Though, why would a hall effect sensor have a acronym of CPS?
 
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