Peterbilt 378 Courtesy Bulb Size
The Peterbilt 378 courtesy light utilizes 1141, 906, 1004, and P21W bulb sizes for the interior lighting components. Available data for the specified vehicle covers the range from 1988 through 1997.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
Bulb Size by Year Range
| Years | Bulb Size |
|---|---|
| 1997 | 1141 (With 4 Rectangular Headlamps) |
| 906 (With 4 Round Headlamps) | |
| 1004 (With Halogen Capsule Headlamps) | |
| 1996 | 1141 (With 4 Rectangular Headlamps) |
| 1004 (With 4 Round Headlamps) | |
| P21W (With Halogen Capsule Headlamps) | |
| 1995 | 1141 |
| 1004 (With 4 Round Headlamps) | |
| 1994 | 1141 |
| 1004 (With 4 Rectangular Headlamps) | |
| 1993 | 1141 (With 4 Rectangular Headlamps) |
| 1004 (With 4 Round Headlamps) | |
| P21W (With Halogen Capsule Headlamps) | |
| 1992 | 1141 |
| 1991 | 1141 (With 4 Rectangular Headlamps) |
| 906 (With 4 Round Headlamps) | |
| 1004 (With Halogen Capsule Headlamps) | |
| 1990 | 1004 (With 4 Rectangular Headlamps) |
| 906 (With 4 Round Headlamps) | |
| 1141 (With Halogen Capsule Headlamps) | |
| 1989 | 1004 |
| 1141 (With Halogen Capsule Headlamps) | |
| 1988 | 1004 (With 4 Rectangular Headlamps) |
| 906 (With 4 Round Headlamps) | |
| 1141 (With Halogen Capsule Headlamps) |
Bulb Specifications
| Description | Bulb Size |
|---|---|
| ANSI standard (US & Canada). Single-filament bulb with BA15s bayonet base. 12V, 21W. | 1141 |
| ANSI standard (US & Canada). Miniature wedge bulb (T10). 12V, 8W. | 906 |
| ANSI standard (US & Canada). Dual-filament bulb with BAY15d bayonet base. Variant of 1157. 12V, 21/5W. | 1004 |
| ECE standard (Europe & worldwide). Single-filament signalling bulb with BA15s bayonet base. 12V, 21W. | P21W |