Buick For Sale 1993 Buick Riviera Alarm Installed At A GM Dealership Prior To Sale.?

1993 Buick Riviera alarm installed at a GM dealership prior to sale.? - buick for sale

This alarm is happened only sporadically, and 4 of the GM dealers have no information about this alarm. Does anybody know where the motion sensor? The brain (module) is under the brake pedal area, without adjusting for the desensitization that .. I went to 8 independent alarm installers and can not find him.