Thread: tach signal wire behind the dash?

I don't know about the Viper but I think the cluster tach is driven by a stepper motor via the PCM.

Some after market tachs are driven by the HB CKP (crankshaft position sensor). I believe that signal goes to the ICM. If I'm right then yes you have to wire into that signal.

I think this is how they get a RPM signal when your car is on a dyno.

Maybe someone else knows better and they'll chime in.

Change to voltage sense and forget about the virtual tach, and physical tach wire. Its in menu 3, option 2

So this thing is a remote starter system?

Looks like the system senses if motor has started two ways:

1. Increased system voltage from the alternator
2. Increased engine RPM

Keith is saying let the system work with #1 and forget about the virtual tach.

Originally Posted by kind153

wait.....voltage and virtual tach is different????? I'm confused.

---------------------------------------
3-2 ENGINE CHECKING VIRTUAL TACH: (1) When set to “virtual tach” the remote
start will monitor the cranking voltage of the vehicle and set that voltage
as a reference point. Fifteen seconds after the crank output sequence the remote
start checks the voltage again to determine if the vehicle is running.
When set to voltage, the unit cranks the starter for the programmed time and
then attempts to sense that the engine is running by detecting an increase in
voltage. When set to Tachometer, the unit references the learned tach signal to
disengage the starter. In addition it will monitor the RPM and shut down if the
engine RPM is too high or too low.
Note: The tach wire must be connected and programmed for the manual transmission
mode to work.
---------------------------------------

apparently!??

Yes. If you set it to voltage sense you should be fine. If it still shuts down, you need to wait for it to shut down and check the LED blinks for the shutdown diagnostics. That will point you to the cause. I had issues with the virtual tach as well. Just switched to voltage sense and that was that.
Basically just open the door, then turn the key to on then off. The hold the valet button until you hear a chirp from the siren. Keep holding the valet button until you hear 3 chirps (3rd menu). Release the button. Then press the valet button 3 times and hold it on the 3rd push. You should hear 2 chirps (option 2). You should only have to push the lock button on the remote once if you are currently on Virtual Tach. You should hear 2 chips and you can release the valet button.