Chevrolet Brookwood Turn Signal Indicator Bulb Size

Additional Notes

• The Chevrolet Brookwood uses three distinct bulb types across its model years for the turn signal indicator: the 194, the 57, and the 257, all of which conform to ANSI standards applicable in both the United States and Canada.
• The 194 bulb is a T10 miniature wedge type rated at 12V and 3.78W. The wedge base design means the bulb is held in place by tension from the socket itself rather than by a separate locking mechanism or bayonet pins.
• The 57 bulb uses a BA9s base and operates at 12V with a draw of just 1W, making it the lowest-wattage type among the three. The BA9s is a small single-contact bayonet cap with a 9mm cap body.
• The 257 bulb is rated at 12V and 2W and is specified with either a festoon or BA9s base. A festoon bulb is cylindrical and held between two end contacts rather than inserted into a socket from one end.
• The Chevrolet Brookwood (1969-1972) uses the 194 bulb for the turn signal indicator across all four of those model years, representing the most consistently applied bulb type in these specifications.
• The 1960-1961 model years share the 57 bulb, while the 1958-1959 model years share the 257 bulb. Despite both being BA9s-compatible types, the 57 and 257 are not the same bulb and differ in wattage and physical form factor.
• The BA9s base shared between the 57 and 257 bulbs does not make them interchangeable. The 257 carries a higher wattage and may also take a festoon form, meaning the socket type in the vehicle determines which of the two is the correct fitment.
• The wedge base of the 194 is physically incompatible with the BA9s sockets used in earlier model years, and no cross-compatibility exists between the 194 and either the 57 or 257 bulbs.