1999 GMC Sierra, Viper 791 XV

I just bought a Viper 791 XV for a 1999 GMC Sierra pickup truck. This will be my first time ever doing an american car. I need to know if there is anything important i should know before the installation. I am not sure what transponder bypass module this car needs. The owner of the car was telling me about some wire that i have to go through but the only way to get to it is by being certified and calling the dealer to know where and what color the wire is in order to install the alarm system. This car has a factory alarm. I do not know if to take it off or not but on other installs that i have done on cars with factory security systems, it has been easier for me to take off the factory alarm.  What would be better? If anyone has any idea of this car, i would greatly appreciate their knowledge. Thanks a lot.

you couldnt have picked an easier vehicle... everything is right below the steering column (Ign wires, BCM) ....passlock II bypass   555L , PLJX or GMBP etc    factory arm/disarm at BCM

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Kevin Gerry
Certified Electronics Technician
MECP First Class Installer

Owner/Installer
Classic Car Audio
since 1979

Thank you very much

Make certain you connect the 2nd ignition. Alot of people find that the vehicle will start by using only the 1st Ignition. Do not omit the 2nd ignition as you will destroy the transmission. It is best to integrate the viper into the existing factory alarm and utilize both systems. The viper provides alarm disarm and rearm outputs to make the two systems work fine together providing even more protection. An alarm such as the one your using is a rather complex unit so if it's your first install it could be a little more than you bargained for. It is achievable but you should study your install manual and vehicle specific wiring diagram and get a good understanding of all that's involved. Ask questions about anything you aren't familiar with so you understand what each function does. Do a search on Sierra and read through other people's posts so you can get a feel for what common problems are and how to avoid them. Don't be afraid to ask if you don't understand something, we will try our best to help you.

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Steve G

Before relays. Use the pink and white ignition wires. your factory arm and dis arm wires are located right below the crash pan that is bolted in under neath the column. Just connect right off the the alarm.

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bryantobando wrote:

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transponder bypassing

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This truck doesn't have a transponder but rather Passlock 2. Use DEI's 555L or a Trilogix GMBP as kgerry stated.

bryantobando wrote:

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This car actually has 3 ignition wires.

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You can omit the brown wire listed as this will only serve to power the radio and sometimes the wipers which are unneccesary during remote start. Most people prefer not to have the wipers come on incase you left the wiper switch on and the windshield iced over. When you remote started it the wipers would try to engage but being frozen may burn out the wiper motor. I also prefer not having the radio and all my amps powered because the volume is usually loud and it wastes energy. Gas prices are high enough these days.

bryantobando wrote:

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The Viper manual says to connect the outputs before relays.

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They are just trying to get you to connect before any high current circuit to protect the low current outputs of the alarm. So connecting at the proper BCM wires would be "before relays" as xtremej stated thus protecting your Viper arm/disarm output wires from overdrawing and burning out.

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Steve G