What year truck?
Wiring Diagrams for 1923 - 1960More wiring diagrams1954 DiagramBulb ChartI just completed refurbishing the gauges on my '54 3100. The truck has been converted to 12v. Here is info for it:
Ignition light, gauge cluster, and Speedo lights come on when the tail lights are on.
One bulb in the ignition switch housing:
6v = #51: 1 candle power, 1.7w @ 7.5v
12v = #53: 0.7 candle power, 1.7w @ 14.4v
Two bulbs in gauge cluster:
6v = #55: 2 candle power, 2.9w @ 7v
12v = #57: 2 candle power, 3.4w @ 14v
Two bulbs on each side of speedo:
6v = #55: 2 candle power, 2.9w @ 7v
12v = #57: 2 candle power, 3.4w @ 14v
Two indicator bulbs in speedo. Both bulbs are surrounded by 1/2" ID cardboard tubes with colored plastic lenses. Red for high beam, green for turn signal. My lenses are gone, so I painted the bulbs with a light coat of red or green rattle can paint.
Top lamp is for high beam indicator
6v = #51: 1 candle power, 1.7w @ 7.5v
12v = #53: 0.7 candle power, 1.7w @ 14.4v
Bottom lamp is indicator for factory installed turn signals, or for after market turn signals with lamp connected to 3-prong flasher (center terminal on flasher, I think) '54 was the first year with an indicator lamp for turn signals.
6v = #51: 1 candle power, 1.7w @ 7.5v
12v = #53: 0.7 candle power, 1.7w @ 14.4v
Later model 12v trucks used a #57, the lower wattage #53 in my truck is plenty bright.
Suggest that you install all new bulbs while you are at it.
