Rear Integration Module (RIM)
WARNING: This page is about a different car, the 2002 Pontiac Bonneville. However, it is still accessible from the selected car via links, so may be relevant.
Ign/Run/Crank: Display indicates ON when the ignition 1 input circuit of the module receives a battery signal from the ignition switch
Brake to Shift Relay: Displays indicates ON when the rear integration module supplies a ground to the brake to shift relay control circuit.