The Pontiac Astre front turn signal requires bulb sizes 1034NA, 1157NA, or 1157, while the rear turn signal uses a 1157 size bulb. The replacement chart covers 1975 through 1977 production years with corresponding bulb specifications.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The 1157 bulb is the most prevalent type across the Pontiac Astre turn signal specifications, appearing in both front and rear positions across multiple model years.
All three bulb types listed in these specifications, the 1034NA, 1157NA, and 1157, share the BAY15d bayonet base, meaning they are physically compatible at the socket level.
The BAY15d base is a dual-contact bayonet fitting, which is required to support the two separate filaments present in all three bulb types.
All three bulb types operate at 12 volts and carry a dual-wattage rating of 21W/5W, where the higher wattage filament serves the turn signal function and the lower wattage filament serves a secondary lighting function such as parking or running light.
The 1034NA and 1157NA variants feature natural amber glass, which produces an amber light output without the need for an amber-tinted lens or housing.
The 1034NA is classified as a variant of the 1157, and while it shares the same base type and voltage rating, it is a distinct ANSI part number used specifically in the Pontiac Astre front turn signal position for the 1977 model year.
The 1157 bulb, which uses a clear glass envelope, relies on the vehicle's lens or housing to produce the required amber color, unlike the NA variants.
The front turn signal position on the Pontiac Astre changed bulb designations across the three model years covered, moving from the 1157 in 1975 to the 1157NA in 1976 and then to the 1034NA in 1977.
The rear turn signal position on the Pontiac Astre used the 1157 bulb consistently across the 1975-1977 model years.
All bulb types in these specifications conform to ANSI standards applicable in both the United States and Canada.