P0340 code

[first&lastKJ]

Two times in the last few days while running around in the wifes 02 it would not start. We had to wait for a bit then try again and it started right up. When we got home I turned the ignition on and off three times and got a P0340 code. Guess I will replace the camshaft position sensor.
Should I stick with OEM?
Also should I replace the crankshaft position sensor while I'm at it or leave it be?

 

[ltd02]

OEM only. I'd just do the camshaft for now. If the symptoms persist then I'd try to do the Crank sensor. That crank sensor can be a BI%CH to get out if this is the first time. I changed mine in my 02 when I had the engine apart and had to drive it in to remove.

 

[Billwill]

Probably the cam sensor but be aware that the "key" method of pulling codes sometimes transposes the last two digits...this according to Lost... so you could actually have a P0304 code which is a valid code!

I personaly have used the key method many times on my 2002 Export CRD with valid results every time....the early KJs use a PCI bus for which obtaining a code reader that works is very hard!

 

[first&lastKJ]

I was doing some reading and it seems the p0340 could indicate a problem was detected in the camshaft position sensor circuit. So it could be the sensor itself, wiring, or PCM.
P0340 could mean a wire or a connector in the circuit is broke, grounded or shorted. The camshaft position sensor may be bad or might have an open circuit.

 

[Billwill]

I was doing some reading and it seems the p0340 could indicate a problem was detected in the camshaft position sensor circuit. So it could be the sensor itself, wiring, or PCM.
P0340 could mean a wire or a connector in the circuit is broke, grounded or shorted. The camshaft position sensor may be bad or might have an open circuit.

Replace the cam sensor with a Mopar one first.

If that does not work re-plug the connectors on the PCM a few times with battery disconnected in to help clean up the connector pins.

If fault is still present we need to climb into the wiring with the help of the wiring diagrams. If you know a good Auto Electrician you can supply him with the correct wiring diagrams...plus the voltages etc. that need to be checked which is explained in the Fault Finding section under the CEL code.

If you do not come right I can guide you through the wiring diagrams...been there done that many times!

 

[first&lastKJ]

Replace the cam sensor with a Mopar one first.

If that does not work re-plug the connectors on the PCM a few times with battery disconnected in to help clean up the connector pins.

If fault is still present we need to climb into the wiring with the help of the wiring diagrams. If you know a good Auto Electrician you can supply him with the correct wiring diagrams...plus the voltages etc. that need to be checked which is explained in the Fault Finding section under the CEL code.

If you do not come right I can guide you through the wiring diagrams...been there done that many times!

Ok thanks. The PCM is on the drivers side correct? Whats the one on the pass. side?
I did unplug the cam sensor and clean plug and sensor. It was covered with oil and 17 years of grime. I plugged it back in, hooked up the negative battery cable and started it up. I took it for a drive everyting seems ok. This reset the CEL and I assume it also cleared any stored codes. The wife wants to drive it and see if and or when it does it again then take it to a shop to have them check the codes with an actual scan tool.

Well she just got home about 15 minutes ago so I had her go try to start it again. It turns over and won't start. She said it ran fine to and from work.

So I guess I will try a new mopar cam sensor tomorrow.

 

[Billwill]

Best that I do not comment on which side the PCM is on as I have a 2002 RHD Export 2.5 CRD 5 speed manual so my drivers side is different and I do not have a TCM which the automatics do.

If you have not yet downloaded the 2002 Jeep KJ Service Manual then here is the link...lots of Theory of Operations and Wiring Diagrams are in Section 8W.

www.colorado4wheel.com/manuals/Jeep/KJ

 

[first&lastKJ]

I replaced the cam sensor tonight with a mopar one. I cleaned the plug with some CRC electronic cleaner, applied some dielectric grease to the plug and hooked up the battery, hope this helps.

 

[Billwill]

Hope it works!

If you have a Multi Meter read the resistance of the old Cam Sensor and then heat up the sensor with a hairdryer. Apparently the resistance should stay the same with a good sensor but changes with a bad sensor.

This is why a hot KJ can fail to start but will fire up when the sensor cools down.
I am curious to know if the above test does work!

 

[first&lastKJ]

Hope it works!

If you have a Multi Meter read the resistance of the old Cam Sensor and then heat up the sensor with a hairdryer. Apparently the resistance should stay the same with a good sensor but changes with a bad sensor.

This is why a hot KJ can fail to start but will fire up when the sensor cools down.
I am curious to know if the above test does work!

Not sure how to do it, I may have to look on you tube.

 

[Billwill]

Not sure how to do it, I may have to look on you tube.

Put your Multi meter...I presume you have a cheap digital Multi Meter....on Ohms. Touch the two probes together...meter should show near to 0 Ohms.

Now touch the probes onto the leads of the now removed Cam Sensor. Do not touch the lead ends with your hands or else your internal resistance confuses things. Take note of the OHMs reading, swap the leads over as you may get a different reading if the CAN sensor is indeed a Hall Effect.

Now heat up the sensor with a hairdryer and see if the resistance changes drastically which indicates a bad sensor.

If you do not have a Multi meter do not bother doing this although I could not think of owning a KJ without a Multi meter in the cargo area at all times! On long trips I always take my Laptop with me so that I can look up CEL codes and wiring diagrams in case I get stuck on the side of the road..has happened a few times!

 

[first&lastKJ]

Put your Multi meter...I presume you have a cheap digital Multi Meter....on Ohms. Touch the two probes together...meter should show near to 0 Ohms.

Now touch the probes onto the leads of the now removed Cam Sensor. Do not touch the lead ends with your hands or else your internal resistance confuses things. Take note of the OHMs reading, swap the leads over as you may get a different reading if the CAN sensor is indeed a Hall Effect.

Now heat up the sensor with a hairdryer and see if the resistance changes drastically which indicates a bad sensor.

If you do not have a Multi meter do not bother doing this although I could not think of owning a KJ without a Multi meter in the cargo area at all times! On long trips I always take my Laptop with me so that I can look up CEL codes and wiring diagrams in case I get stuck on the side of the road..has happened a few times!

It took me a few tries to get a reading from two of the three leads on the sensor.
Meter set on OHMs 2000k, reading was 1770.
Turned on hair dryer and it started to drop. Went down to 650 and fluctuated a little from there.
Turned hair dryer to cool and the reading began to climb slowly.

 

[Billwill]

It took me a few tries to get a reading from two of the three leads on the sensor.
Meter set on OHMs 2000k, reading was 1770.
Turned on hair dryer and it started to drop. Went down to 650 and fluctuated a little from there.
Turned hair dryer to cool and the reading began to climb slowly.

Thanks for the input...nice to know that there is indeed a way to test these cam and crank sensors.

Lost has a few similar posts.

 

[first&lastKJ]

Well it's been two weeks and no more issues since replacing the cam sensor.
Thanks for your help Billwill!