I could not get the VIPER to "chirp." I only get horn beeps.
This is common is some applications. Keyless entry without an alarm or an application where an aftermarket alarm can mimic a factory alarm. The alarm brain can be set to run a siren, or a horn and in most cases never both. Although, there are always exceptions to the rule. If you do not see an alarm horn mounted in our around the engine bay then there is most likely no siren "alarm horn" so you will never get a "chirp". DEI the manufacturer of the Viper alarm uses a very standard color scheme for all of the their alarms. ie Clifford, Viper, Valet, Hornet, Python ect. If you follow the brown wire from the alarm harness it will go to the horn (Black wire at steering column) or a siren or both separated by a pair of diodes to isolate the circuits. If you have more than one brown wire which is possible it will depend on which harness on the alarm brain the brown wire comes from but lets tackle that later. I doubt this is a remote start alarm so you need not worry about that.
A sticky note was up there explaining the VIPER was wired there to open a garage door.
Anything can be wired to an extra channel on an alarm as long as you know how to use it. Relays can be used to funnel extra power and resistors can be used to buffer power to use any electronic device. Chances are the PO had one of the extra channels set up to apply power to the circuit within the garage door opener. Personally that's a bit odd but to each his own.
1) 4X4 indicators light works intermittently.
2) Clicking at TCCM (when it doesn't click - indicator lights work. 4X4 still engages with or without clicks.
Trace the wiring from the light back to the fuse panel. There may be a short, splice, or cut. Also try replacing the bulb. May just be a bad filament.
Can anyone tell me what wires come from the door locks to the VIPER "brain" under the dash? It looks like there's an aftermarket alarm wiring harness down there with the red VIPER LED and the valet button dangling from a wire.
Once again DEI uses a standard set of colors for their alarm harnesses. The valet switch is used for programming and to take it in and out of valet mode with the use of your ignition key. The wires for the valet switch are almost always gray and gray/black. The LED is almost always red and black or red/black and rarely connect to the main harness of the alarm. There are almost always side ports for those. The door lock harness is usually a 2 or 3 wire harness in the alarm or part of the main harness for the alarm. Green and Blue with an empty slot. Green (-) LOCK (+) UNLOCK output from alarm and Blue (+) LOCK (-) UNLOCK output from the alarm. So if you trace these wires back you can find out where they intersect the Light Blue and White door lock and unlock wires above the gas pedal at the factory GM lock relays.
TIP: Make sure you check all the door lock fuses in the fuse panel and verify that the lock and unlock work when using the buttons in the truck. If that doesn't work neither will the alarm. If I am not mistaken the 99 door locks are part of the cigar lighter circuit so if that failed the door locks are not working. Oh and here is another tip: before throwing a new fuse in make sure the cigar lighter is not short circuited behind the dash. If that lights up you will be doing a lot more then trying to figure out why lights a locks don't work.