THM 400 Only
WARNING: This page does not describe the selected car, but rather 28 other vehicles, including the 1987 GMC Vandura Special, 1987 GMC Vandura, 1987 GMC Value Van, 1987 GMC Suburban, and 1987 GMC Safari. However, it is still accessible from the selected car via links, so may be relevant.
With engine off, push detent switch plunger as far forward as possible. This presets switch for adjustment. Depress accelerator pedal to wide open position. Switch will self adjust. Operation of detent switch circuit can be checked by connecting a test lamp across switch terminals.