Pontiac Problems? Ask a Mechanic for Answers ASAP
I am sorry that you have not been helped yet. I just came online and saw your question.
Unfortunately, this is going to be near impossible to impossible to diagnose online without being able to converse with the person that installed it as I need to know the brand and model number of the aftermarket system installed, as well as exactly how it was installed - function of each wire on aftermarket unit and exactly where it was connected to and how it was connected(straight to a fuse, spliced in with butt or splice connector, soldered in and heat shrink used to cover the solder joint).