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?

There is a thick loom of wires that run across the engine from the driver's side to the passenger side. It is split tube loomed aswell as the wires in there are taped up. Ther eis only one VIOLET/WHITE wire in there.

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Jeff
Velocity Custom Home Theater
Mobile Audio/Video Specialist
Morden, Manitoba CANADA

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.

The voltage is actually a pulsating DC voltage.   This makes it hard to read for some meters.  But those meters will usually pick it up as a DC voltage.

Thanks very much everyone. It was the correct wire. The unit is working now!
I just need to connect the door locks and I can consider it done!
There is keyless entry already, but doesn't have an alarm. Blue and white wires should do it.

In the driver's kick panel, there is a bunch of wires taped up that has the OEM alarm wires as well as the lock and unlock wires and this bunch of wires you can pull out from the driver's kick panel about 6-8 inches. As you stated, use the BLUE and the WHITE wires for the lock and unlock.

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Jeff
Velocity Custom Home Theater
Mobile Audio/Video Specialist
Morden, Manitoba CANADA

Oh brother. Right when it was supposed to get easy!
I can't find these wires. Well I see a bunch of wires taped up. Looks like some go from maybe the door rubber 'boot' that you see when the door is open, and down under the carpet towards the back seats. These ones? I pulled the plastic off beside the door in order to see the hole where these wires head up and out towards the door 'boot'

Now I have another question:
I thought I needed extra relays to trigger the door locks. But then I read this in the door lock part of this website:
"3 Wire Positive Door Locks
This is one of the most common type of door lock switch configurations found in most vehicles. In most cases you will not need to add relays for this type. Most of the newer alarms and keyless entries on the market today have both positive and negative 200 ma door lock outputs that are usually capable of activating the factory relays."
My starter has a 500mA output for the locks.
Is this enough? Maybe I don't need those relays I have connected and ready for when I figure out where the wires are!