2004 montana tach wire

I expect this has been answered, but I have searched and an unable to find! The information I have says the tach signal wire should be in the "big harness" in the engine compartment. It is a PURPLE / white wire. I cut open the big harness and found a purple wire with a white stripe. I inserted a pin into the wire, and put an AC volt meter on it. While revving the engine, the voltage was around 2volts, and did not fluctuate. Is this the correct wire? How can I measure it? Is there a place to get a picture of it to help me confirm?

I have a diagram that shows there are no pins present on pin 8 of the BCM connector. I have not physically checked yet to confirm this. I would prefer not go right off the coil, but rather tie in to a wire in a harness. I read about this wire in the large harness in the engine compartment. Some wire "diagrams" only suggest coil, while others say PURPLE / white wire in harness.

Oops! I just noticed you have PCM, not BCM. What/where is PCM?

Thank you very much. This is exactly what I am looking for. I cut into the wire that runs horizontally from drivers to passenger side as you say. It was a split loom with the wires all taped. I'm sure it is the same bunch of wires. Should I be able to measure an AC voltage that fluctuates with engine rev? Thanks again

That depends on the quality of your meter.  Try it on DC volts also, one of them should show fluctuations relative to engine speed.

Funnily enough I used a DMM yesterday for the first time on an MR2. Correct readings should be 2.3 to 5.5 volts with meter set to 20vAC I must that this was in the pouring rain, the vehicle had a fault on the ignition switch AND the factory alarm and I couldn't get a definite reading from my trust MAC 120 LED probe.

I was using a DMM as well. I didn't know what the voltage should be, so thank you...but my biggest concern was it didn't seem to fluctuate when I revved the engine. I am going to assume based on the previous posts that I do in fact have the correct wire, and connect and test. I will keep you posted.