The White/GMC WX uses a 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 WX uses the 1157 bulb for both its front and rear turn signals across all listed model years from 1988-1995.
The 1157 is an ANSI-standardized bulb type, meaning its specifications are governed by a formal industry standard recognized in both the United States and Canada.
The 1157 is a dual-filament bulb, which means it contains two separate filaments within a single glass envelope, allowing it to serve two distinct lighting functions from one unit.
The 1157 operates on a 12-volt electrical system, consistent with the standard automotive voltage found in most passenger and commercial vehicles of this era.
Its two filaments are rated at 21 watts and 5 watts respectively, with the higher-wattage filament typically serving the turn signal or brake function and the lower-wattage filament serving a parking or running light function.
The 1157 uses a BAY15d bayonet base, a two-pin offset base design that physically prevents incorrect insertion, as the two pins are positioned at different heights on the base.
Because the front and rear turn signal positions on the WX share the same 1157 specification, a single bulb type serves all four turn signal sockets on the vehicle across the entire 1988-1995 production span.
The BAY15d base is not interchangeable with single-pin bayonet bases such as the BA15s, and substituting a single-filament bulb in a dual-filament socket would result in the loss of one lighting function.