Hi, Yesterday I had a simple car alarm (Viper 3105v) installed in my 2001 Ram Van 3500. The alarm works but before leaving the shop parking lot the following (new) problems presented- "ABS" & "AIR BAG" dash warning lites stay on, the A/C compressor did not come on (jumper wire indicates compressor itself OK) and the aftermarket "back up beeper" did not sound off in reverse. Of course shop says the didn't do it.
After leaving the shop I found additionally- speedometer/odometer, wipers/washers and aftermarket "Penntex" high idle device all don't work either.
All these systems had been working and stable for the year I've owned the vehicle prior to all this. No OBDII show up and initial inspection does not find blown fuses.
Would anybody have an educated guess as to what might have happened? With so many unrelated failures I'm going to start by looking for a disconnected or bad ground somewhere but beyond that am at a loss where to look. Any suggestions would be greatly appreciated.
Thanks in advance.

I had the shop look for the problem before I ever drove out of their parking lot. They said they didn't cause it and that was the end of their story until I said I'd be back the next day with a large picket sign. Talked to the owner later that day and he said if I could get a diagnosis that showed they caused problems he would pay for diagnosis and fix. Chances are very high they caused this but diagnosis they will accept as indicating that they caused it not so high. So my first step is to look into this myself and if I can't figure it out then I get the diagnosis and start spending the bucks I may or may not get back.

Ive pulled plug on the whole alarm with no fix. I don't think alarm is cause but something caused installing it. With so many systems out cause maybe like ground disconnected, PCM shot or some other major blown electronic. Anyway taking for pro diagnostic later today.