Chevrolet Bel Air Engine Compartment Light Bulb Size

Additional Notes

• The Chevrolet Bel Air engine compartment light uses four distinct ANSI-standard bulb types across its production span: the 1003, 93, 1156, and 94.
• Three of the four bulb types specified for the Bel Air engine compartment, the 1003, 93, and 1156, are single-filament bulbs operating at 12V and sharing the BA15s bayonet base, though they differ in wattage.
• The 1003 and 1156 both operate at 21W on a BA15s bayonet base, making them electrically similar despite carrying different ANSI designations. The Bel Air uses the 1003 for model years 1972-1975 and the 1156 for 1965-1966 and 1968-1969.
• The 93 bulb is a lower-wattage variant of the 1156, rated at 13W rather than 21W, while retaining the same BA15s bayonet base. The Bel Air uses this bulb for the 1967 and 1970 model years.
• The 94 bulb is the only dual-filament type in these specifications, rated at 21/5W and fitted with a BAY15d bayonet base. Its base type is physically distinct from the BA15s used by the other three bulb types, making it non-interchangeable with them.
• The 94 is described as a variant of the 1157 and was the specified engine compartment bulb for the Chevrolet Bel Air from 1955-1963, the longest continuous span of any single bulb type in these specifications.
• Because the BA15s and BAY15d bayonet bases are different, bulbs from the 1955-1963 fitment group cannot be substituted with bulbs from the 1965-1975 fitment groups without a base mismatch.
• Although the 1003 and 1156 share identical voltage, wattage, and base type, they carry separate ANSI designations and are not formally listed as interchangeable within these specifications.