Electrical Circuit
WARNING: This page does not describe the selected car, but rather 35 other vehicles, including the 1992 Pontiac Trans Sport, 1992 Oldsmobile Silhouette, 1992 Oldsmobile Bravada, 1992 GMC Yukon, and 1992 GMC Vandura Special. However, it is still accessible from the selected car via links, so may be relevant.
Disconnect wire from switch terminal on combination valve. Connect wire to ground. Turn ignition on. If brake warning light does not come on, repair brake warning light bulb or wiring circuit. If light operates, brake warning light electrical circuit is okay.
NOTE:
On Astro and Safari, system is not equipped with pressure differential switch.