wait to start wire

i am going to be installing a audiovox aps57c in a 2003 Chevy 2500 hd duramax. It has a diesel option for a timed start delay and also a wire to hook to glow plug wire or wait to start bulb. it says the wait to start wire should be + 12v them go to ground. Then the the truck should start 1/2 second later. The wiring diagram i found says the dark blue wire for the wait to start bulb is negative polarity does this wire have 12v + while the glow plugs are on? are there any problems with using the time delay for start like starting before the plugs are up to temp or waiting to long? Where is the best place to tie into the glow plug bulb wire providing it will work for this remote starter? this is a Christmas present for my son so i cant be poking around on his truck right now without tipping him off on what i have got him. i have installed several remote start systems but never in a diesel. thanks for your help.

Have done hundreds of these by using 20 second wait to start in timed start mode. No WTS wire needed. Waiting too long to start does far less damage than trying to start while it is still warming. It should automatically stop warming when the temperature is reached. We would be talking minutes not seconds to cause harm or to miss the opportunity to start.

Timed start 20 second delay and it will be good to go!

To master and control electricity is perfection. *evil laugh*