Jeep TJ/XJ Camshaft Position Sensor Testing Procedure

I will take you through a complete testing procedure for a camshaft position sensor for Jeep TJ & XJ. I make many references to pins & cavities. These tend to be the same across all the years, but I know specifically that 2005-2006 has different paths to the PCM and 97, 05, and 06 TJ's have the 5V supply & sensor signal wire flipped at the sensor. Consult your factory service manual to validate the pinouts for your vehicle.
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Products Used:
USB red/black alligator clips: a.co/d/ipFLuFb
Alligator clips: a.co/d/gABAaZA
Arduino Oscilloscope: a.co/d/31r1yxb
Digital Voltmeter: a.co/d/0F5XDw2

[@nevadaboy9769]

Thanks for the learning session👍before you said anything about an assistant i noticed him in the truck, scared the shit out of me when he moved lol

[@dannyshafer8357]

Great video

[@bigjuicygarage4754]

Thank you, my dude!

[@daveo.5479]

thanks! took some notes. will help if I ever need to troubleshoot

[@bigjuicygarage4754]

Awesome, I hope you never need those notes or this video!

[@IAmRootGarage]

I have a weird issue with my 98 TJ 4.0. It seems to run perfectly till about 70 and it starts stuttering really bad. After a lot of diagnosis, I know it is a spark issue. I can drive it with a fuel pressure meter and it never wavers. No check engine code. My suspicion is that there is a kink in the supply wire from the signal of the cam sensor to the computer. While it checks out fine with an ohm meter, I worry that it looses connection at 70 (It always happens at 70, but sometimes it happens at other speeds usually when hitting it hard). I have messed with the harness and it seems to make a difference, but I don't know if it is because I actually stopped the TJ or there is an actual issue in the harness. So my TJ is not a show truck by any means, and I think my next step is to cut the signal wire somewhat close to the ECU and at the other end at the cam sensor and try running a new wire, so my question to you because you seem a bit smarter than me is do I have to match the size of the actual wire, meaning if the one I have is slightly bigger will that change the frequency going to the computer? Or do you know the actual gauge of the wire? I subscribed and thanks in advance. I am really trying to decide if it is a wiring issue or the actual ECU.

[@bigjuicygarage4754]

You don’t need to match the wire gauge, within reason. I don’t have access to the FSM, but I believe those wires are 18ga, which is readily available from any parts store. You’re sure messing with the harness can affect the problem? Also have you tried holding that 70mph RPM in a different gear? I can’t believe it’s *speed* dependent, it’s got to be RPM dependent. I’m wondering if your distributor or OPDA is part of the problem.

[@IAmRootGarage]

@@bigjuicygarage4754 I have a distributer, It is brand new (aftermarket as new ones don't exist anymre) I am not sure about the wires it is possible that it is a coincidence. If I do switch gears the speed changes so it clears up. but once it starts sputtering it is like it is shutting down the engine and restarting it really fast and I have 4:88 gears so once there is a disturbance it drops 10 mph instantly and clears up. It isn't always exactly at 70 but it always starts above 70 and there is not check engine light even when it is sputting or (shutting off) That is my issue. That is why I feel like it is a wiring issue. I feel like if it was computer related it would send a code and or run rough but not actually kill the engine and instantly start up again.

[@bigjuicygarage4754]

@@IAmRootGarage I’ve seen enough cam/crank sensor issues without a code being thrown, and this definitely feels like that. I hate firing the parts cannon, but if you’ve verified the wiring is solid, I might start with a new cam/crank sensor. But I wonder if the dizzy/cam tone wheel is off just enough to cause the timing advance to be too far advanced once you get to that RPM? Note the RPM when it happens, not the speed. The vehicle speed should have nothing to do with it.

[@nevadaboy9769]

i pulled the wire connector off the cam sensor with the key on i am getting 5v thru the supply and signal wire both at the connector, the same goes for the crank & throttle position sensors! all 3 are disconnected, i thought the only time the signal wire should have any voltage is when the sensor sends it thru that wire back to the pcm, am i wrong or do i have a bad pcm or the wires are pinched together some where Thanks

[@bigjuicygarage4754]

There’s some magic inside the PCM that puts 5V on the signal wire when the sensor is unplugged, so I think you’re safe. (Also welcome to www.wranglertjforum.com) 😉

[@nevadaboy9769]

@@bigjuicygarage4754 yep you are correct, i posted that question on wranglertj forum & a few ppl replied saying that the pcm does some trickery and supplies th signal wire with voltage if the sensors are unplugged! so back to square one have to somehow do what your doing to the crank, cam & throttle position sensor

[@bigjuicygarage4754]

@@nevadaboy9769 yeah, I was one of the replies. 😘