Thankya Tyler. I have been bangin my brain on this thing and over thinking everything. I thought the CMP signal just looked "noisy". I asked a mechanic friend if he knew anyone at his shop with a 4 channel scope and I would pay them for their time to come out and plug in.
@Tyler After you mentioned the subtle spikes on the Cam sensor that I mistook for sign wave noise I went back and took some more readings and the results were interesting. The first 3 screen shots I am attaching were done at the Cam sensor connector at the distributor. The next 3 were done at pin #44 on the PCM connector, same tan/yellow sig wire, and got different results. Note the voltage difference between the 1st set and second set as well as the dropout on the second set.
That might explain why you're seeing good amplitude at the sensor, but not at the PCM. Not sure where the ground voltage ties in yet.
I'd scope the 5V reference and the sensor ground next. Look for similar changes in either. If the both look steady, I'd chase an excessive voltage drop on the cam sensor signal circuit.
Thankya T. I have the Chrysler service manuals for the jeep. I did the test you hyperlinked already, was one of the very first. So I never bothered voltage drop testing the circuit. I did also check all grounds including the shared sensor ground. Everything showed 250mV or less ground to ground (although I did that test with a meter not scope). I observed on the sign wave, at the cam sensor connector, that the ground was coming up to about 760mV and 5V was spiking up to 5.6V. then testing at the PCM pin the 5V ref dropped to 3.6V. to my knowledge a computer can't function correctly despite the drop out in the signal. This wreaks voltage drop on the circuit to me. Thoughts?
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