As with many other items on the Advance Design Series trucks, there were also changes in the ignition switches. Both Chevrolet and GMC shared their several switch changes during the seven year series.
In the beginning (1947-1948) a unique three position ignition cylinder and housing was introduced. This was a first for GM trucks. It related to a country with limited crime and a time when many people did not lock their houses. The switch allowed the truck to be started without a key.
By turning the cylinder and key to the far left, the ignition switch was locked. However, the middle position was the big difference! Here the ignition was still off but a small tab or teardrop extending down from the cylinder face allowed the driver an option. With a touch of a finger you could turn the cylinder clockwise with or without a key due to the teardrop. This 1947-48 feature was convenient for many owners, particularly on a farm. No longer did they worry about losing the key or having to dig when it was in a pocket.
When the key was moved to the far counterclockwise position, the ignition was locked. This security feature was built in. The switch could not be locked without the key, so no worry about it accidently moved to the locked position.
This three position switch, also used on the 1948 Chevrolet car, was discontinued about the end of 1950. GM then returned to the two position on-off cylinder and housing that would not operate without a key.
Between 1947-1953 the switch and cylinder combination plus a one candle power bulb and socket was attached to a sheet metal housing. This assembly is screwed to the top of the lower dash lip out of sight. Only the round key cylinder face is seen by the driver. It extends through a larger hole in the dash. A resulting 1-1/16 inch circle opening between the dash and this cylinder face produces a lighted ring at night from the adjacent small bulb. This allows the driver to easily locate the switch in the dark.
In 1954, with the total redesigned dash, there was a complete change in the ignition switch housing. The threaded end of the die cast housing is held in the dash by a chrome lock ring. Only this ring and the key cylinder face is visible to the passengers. It is also the two position on-off type as the key cylinder did not change.
With the introduction of Hydramatic transmission during these years the switches did not change. The starter motor was activated by a button near the headlight switch not by the ignition switch.
1947-48 1949-53 (Both in lock position)
1954 Ignition Switch
1954 Ignition Switch with Light Bulb Socket Hole