The Stovebolt Site Forums The Shop Area The Electrical Bay Turn Signal Problems

If this post just confuses things let me know and I'll get rid of it.


I was troubleshooting a turn signal problem on my '57 GMC 15 years ago and couldn't find a diagram of the inner workings of a six wire GM turn signal switch. So I took mine apart and made the drawings below from what I found. With the exception of 7th (usually blue) wire, my drawing works with the 7 wire Signal Stat turn signal switch and knock offs from other companies. The 7th wire does not actually participate in the switch's function, it just connects the flasher to the light inside the turn signal unit.

The wire colors in my drawing are correct for OEM 54-59 Chevy/GMC 6 wire turn signal switches. The wire colors on a Signal Stat 900 (and knock-offs) are different, but function the same way. Your wire colors may vary, but the place they connect to will not.

The black dots are fixed (non moving) contacts inside the switch. The yellow pieces are movable contacts. They slide left and right as a group to connect and disconnect brake light and turn signal functions when the driver uses the turn signal lever.

The first drawing is with the turn signal in the off position. The flasher is disconnected as are both front turn signal lamps. The wire from the brake light switch is connected to both rear turn & brake lamps.


The second drawing is with the turn signal in the right turn position. The flasher is connected to the right front turn signal lamp and the right rear turn & brake lamp. The left front turn lamp is disconnected. The wire from the brake light switch is connected to the left rear turn & brake lamp.


The third drawing is with the turn signal in the left turn position. The flasher is connected to the left front turn signal lamp and the left rear turn & brake lamp. The right front turn lamp is disconnected. The wire from the brake light switch is connected to the right rear turn & brake lamp.