The Isuzu FXR uses a 1157 bulb size for front turn signal applications and a 1156 bulb size for rear turn signal applications. The replacement chart covers vehicle production spanning 2004 to 2011 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 Isuzu FXR uses two distinct bulb types across its turn signal positions: the 1157 at the front and the 1156 at the rear, a split that holds consistent across the 2004-2011 model years covered in the specifications.
Both the 1157 and 1156 are ANSI-standardized bulbs recognized in the United States and Canada, operating on a 12-volt electrical system.
The 1157 is a dual-filament bulb, meaning it contains two separate filaments within a single envelope. This allows one filament to handle turn signal flashing while the other serves a secondary steady-burn function.
The 1157 uses a BAY15d bayonet base. The BAY15d designation indicates an offset dual-contact base, where the two pins are positioned at different heights to prevent incorrect installation.
The 1157 draws 21 watts on its primary filament and 5 watts on its secondary filament, reflecting its dual-function design.
The 1156 is a single-filament bulb rated at 21 watts, dedicated solely to one lighting function, which in the Isuzu FXR rear position is the turn signal.
The 1156 uses a BA15s bayonet base. Unlike the BAY15d, the BA15s is a single-contact base with symmetrically placed pins, making it physically incompatible with the BAY15d socket used by the 1157.
Because the 1157 and 1156 use different base types, the front and rear turn signal bulbs on the Isuzu FXR are not interchangeable with each other, despite sharing the same 12-volt operating voltage.
All specifications across the 2004-2011 range carry the Tilt Cab designation, indicating these bulb sizes apply specifically to that cab configuration of the FXR.