The White/GMC ACL uses 1157 bulb size for both front and rear turn signal applications. Replacement chart data covers 1988 to 1995 production years with corresponding bulb size specifications.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The White/GMC ACL uses the 1157 bulb for both front and rear turn signals across all model years from 1988-1995.
The 1157 is a dual-filament bulb, meaning it contains two separate filaments within a single glass envelope, allowing it to serve more than one lighting function.
The 1157 operates on a 12-volt electrical system and draws 21 watts on its high-intensity filament and 5 watts on its low-intensity filament.
The 1157 uses a BAY15d bayonet base, which features two offset pins at different heights to ensure the bulb is seated in only one rotational orientation.
The 1157 conforms to ANSI standards and is recognized in both the United States and Canada, reflecting a standardized specification shared across North American markets.
Because the front and rear turn signal positions on the ACL share the same 1157 specification, a single bulb type serves both locations on the vehicle.
The BAY15d base of the 1157 is not interchangeable with single-pin bayonet bases such as the BA15s, as the dual-offset pin configuration is physically distinct.
The 1157 should not be substituted with the visually similar 1156, which carries a single-filament design and a BA15s single-pin base incompatible with dual-filament sockets.