Intermittent sensor malfunction troubleshooting technique 2005 Jeep LJ

Hello all

Car is a 2005 Jeep LJ

New to the forum. I’ve been watching the videos and reading material on troubleshooting a cam sensor malfunction.

What hints/techniques do people suggest to troubleshoot an INTERMITTENT cam position sensor (p0344) malfunction? Especially one where the condition that’s sets it off is unknown though seems to happen with prolonged run time.

Alldata suggests scoping while juggling the wires and harnesses at various points.

Hints? thoughts?

Thanks!!

Intermittent problems suck, plain and simple. :evil:

Are there any symptoms/drivability issues? Or just a light/code setting? How intermittent is it? Once every 3-4 weeks? Or is it likely to happen every drive cycle?

A wiggle test is, definitely, something to try. Connect a scope channel to each wire of the crank sensor. If you can change the scope pattern by wiggling wires, then you are on the right track.

I would try to capture a crank position waveform, during the code setting. Code setting criteria is 20 failures in one trip, so this may be easier said, than done.

Depending on what scope you have available to you, I would capture a very long waveform, maybe a one-minute capture. Then, plot the frequency of that waveform. This will make any anomalies in the signal stand out like a sore thumb.

It happens every 3-4 days if I’m driving every day. Longer if I’m not driving it. It’s a third car. When the CEL is on it’s in limp mode. Between it’s 100% problem free. That’s why I kinda suspect a wiring short.

I have an AesWave uScope basic and an Autel MK808 as my diagnostic setup. I can definitely wait till the code comes back. It always does.

It’s currently having the OPDA replaced. I have an oem sensor from a wrecked jeep. After it returns I plan on making sure the cam/crank sync is at 0 degrees and doing a relearn. Hell that make fix it but am also planning on testing the wiring.

Not sure what an "LJ" is, or what engine is in your Jeep, but I can tell you from the pain of experience that most Chrysler/Dodge/Jeep products do not like aftermarket sensors.

Sorry I wasn’t clear!

It’s a 2005 Jeep TJ with the 4.0. I’ve scoured parts yards and part outs and found one cam sensor I’m almost sure is original and another that is probably original. Otherwise the echlin sensors seem to work well.

I’m just preparing for what I’ll do it both the OPDA and CPS are changed and CEL 0344 comes back. Plan will be to check wiring as I mentioned above and the crank sensor.

Chad wrote:

Intermittent problems suck, plain and simple. :evil:

Connect a scope channel to each wire of the crank sensor. If you can change the scope pattern by wiggling wires, then you are on the right track.

I would try to capture a crank position waveform, during the code setting.

Great advice there.

I would add that if you do scope it then:

If 3 wire sensor then probe the 5 / 12v Supply & Ground at the Sensor and the Signal at ECU Plug

1f 2 Wire then then both at ECU.


There are several DTC,s that a Cam Sensor can raise

P0340 - Camshaft Position (CMP) Sensor Circuit
P0341 - Camshaft Position (CMP) Sensor Performance
P0342 - Camshaft Position Sensor Circuit Low Input
P0343 - Camshaft Position Sensor Circuit High Input
P0344 - Camshaft Position Sensor Circuit Intermittent

Yours is 344 - INTERMITTENT hence a Scope may be the only way to catch it