1999 Tahoe remote start

I  installed it yesterday almost everything coneected but the tach wire the third ingition wire and the remote start activation wire. I having trouble locating the tach wire that say it white located at the ecm. I connected to the white wire on the black plug side marked white is this correct. After some research that say it is a third ingition that is brown that need to be connect to in order for the remote start to work what do I hook this wire up to. And where do i need to connect the remote start activation (-) wire too.  I have a viper 791xv.  This is the WHITE/ blue on the main harness.

WHITE/ blue is not needed

Okay Thanks, Do you know about the brown ignition wire where do i need to connect it to, do i need to wire it on a relay. and the other small  4pin wire from the relay switch blue (-) statusm orange (-) 200mA 2nd acc., purple (-) 200mA starter, pink (-) 200 mA 3rd iginition output connects to. 

the brown is actually the second acc. used for radio. if you want your radio to come on then yes wire it to a relay to the orange 2nd acc lead.

The white wire in cavity #6 of the instrument cluster plug is your tach wire.sparky

How do I wire up the blue/white (-) 200mA 2nd status/defogger for defrost on chevy tahoe.