White/GMC WXLM front side marker bulb uses 1157 size while rear side marker bulb uses 194 size. Replacement chart covers 1991 to 1993 production years with bulb specifications.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The White/GMC WXLM uses the 1157 bulb for the front side marker position across the 1991-1993 model years.
The 1157 is a dual-filament bulb with a BAY15d bayonet base, rated at 12V with a 21W/5W filament configuration, and meets ANSI standards for the US and Canada.
The dual-filament design of the 1157 means it carries two separate filaments within a single envelope, each operating at a different wattage.
The BAY15d bayonet base features two offset pins, which physically prevents single-filament bayonet bulbs from being seated in a socket designed for the 1157.
The rear side marker position on the WXLM uses the 194 bulb across the 1991-1993 model years.
The 194 is a miniature wedge bulb in the T10 form factor, rated at 12V and 3.78W, also conforming to ANSI standards for the US and Canada.
The wedge base of the 194 relies on the tension of its wire leads rather than a locking mechanism, making it a different fitment type than the bayonet-based 1157.
Because the 1157 and 194 use entirely different base types, one is not interchangeable with the other regardless of voltage compatibility.