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The cam sensor ground also shares with the MAP/air temp sensor and also shares with the coolant temp sensor, iv attached a pic of the diagram, the cam sensor is the one with the red box around
We need to know circuit design here. Your cam sensor photo had the spikes I didn't like on both green CAM PWR trace and Yellow signal trace and they are in sync with each other!, Judging by the scales the voltages are being pulled down during this spike event.
So, with KOEO is the cam signal high or Low with the sensor disconnected?
If its High, its pull-down design, then you will want to make sure nothing else but the sensor is pulling the signal to GND
If its Low, its pull-up design, and you will want to make sure no other voltage source is contacting the signal wire. (such as the reference voltage in the same harness) or any other for that matter.
That spike event tells me something has tried to pull voltage down. To pull voltage down you need an intermittant GND in your case.
My next step would be to determine circuit design and perform by-pass test with the scope, where you are being the sensor. IF you can re create that small spike, youve got a wiring issue, my guess would be Grounds.
If you can recreate a nice clean signal, replace the sensor.
Since were on the topic of possible grounds, unplug the cam sensor, unplug the cam signal at the PCM and ref voltage at pcm, Attach your test light to B+ and check the signal and pwr FEED. The test lamp should NOT light up here. IF it does you got some wiring to repair.
Vice versa attach to BAT GNR, rechech those wires for a presence of voltage while all unplugged/ The lamp should not light. if it does you've got voltage that should not be there.
Feel very free to wiggle the wires vigorously as possible while using the test lamp.
The circuit is a pull down so with KOEO and the cam sensor disconnected the sensor is at 5v.
Ill use my test light with the signal wire scoped and touch on and off and see ifi can create some nice smooth square waves like you said.
After doing that if i manage to create them nice square waves ill replace the sensor with a VW OEM cam sensor because the current cam sensor is an aftermarket one.
If i dont manage to get the nice square waves ill proceed to do the other test by disconnecting the sensor and also disconnecting it at the PCM and do the test light test for wiring integrity.
"If i dont manage to get the nice square waves ill proceed to do the other test by disconnecting the sensor and also disconnecting it at the PCM and do the test light test for wiring integrity."
You test wiring integrity by voltage drop testing with the circuit live.
You don't necessarily have to use the test light, you could though, a voltmeter would be better for checking for the presence of voltage when everything is unplugged, and checking for a short to GND on an Ohm scale. Please use both! Just Make sure you polarity is correct when using the test lamp
Right so today iv just managed to do a test light test on the cam signal, i unplugged the cam sensor and scoped the signal wire and front probed the signal wire carefully and then put my test light on B- and tapped on and off the front probe to try recreate the a clean signal, i think i created a decent singal so i then reconnected the cam sensor and watched it for a while and saw a 0.5 volt spike drop again and also a 2v spike drop from 5v to 3v. I then got my test light and started to tap on top of the cam sensor and after some tapping the cam sensor wave went haywire it just went crazy and then dropped to 0v for a good 5-10 seconds before coming back to normal. I then waited a few mins and tryed tapping again to recreate it but only managed to get it to go crazy that once and then had to stop because i needed to go shopping hahaha so i didnt get any more time to try recreating it going crazy again.
I would think that is conclusive evidence enough, to by-pass test and watch the scope create a clean signal. Then you plugged it back in and noticed the spiking. The spiking can only come from the sensor itself, or what the sensor is being signaled from which is the tone ring. It would be a pretty safe bet it's the sensor.
Your wiring integrity is obviously good to the PCM. You could Vdrop the sensor wires(circuit loaded), but that would be overkill.
Post a picture of the old sensor with the spike and the new one without if u can.
Ye so basically the only test i didnt do was going to the pcm and unplugging the cam and testing it from there, and then like i was saying when i have just tested the bypass test and created the signal i could basically creat a square wave by tapping on and off with a nice rytham.
Ill get my girlfriend to get a new cam sensor from vw and then ill scope it and post them pics
