is this my tach wire?

I'm just about done installing a Viper remote start on a 2004 Hyundai Tiburon. I'm stuck on the tach wire though.  The wiring diagrams I have looked up specify it is a white wire in passenger kick panel in a 23 pin connector.  I found this wire, but it has a constant 5VAC signal on it as long as the engines running and 0v when the engine's off.  Sounds good, except, the voltage does not vary with rpms as I would have expected it to.  Is this still a valid tach signal?

 Doesn't sound like it. The tach should increase or decrease with rpm.

I've used quite a few tach connections that don't vary with RPM. The remote start system is measuring frequency, not voltage, so a voltage variance with RPM isn't essential. If you're getting 5VAC on the wire with the engine running, and it's the wire specified in your reference, then I'd use it.