Turn Signal Systems
Turn Signals were not required equipment tell 1962, so 1960-61 truck had this as an option.
Most trucks came from the factory with them installed, but some did not. There was a Dealer
installed kit for these & some just got added by the owners. The factory & dealer installed
kits has a cable running up the column & a switch mount near the bottom of the Column.
Also the dealer installed kit came with lights that mounted on the side of the truck.
Most added on by the owners are the type that mount to the out side of the column.
1960-61 Dealer Installed Turn Signal Kit
If your problem if in the turn switch itself, then you may have trouble finding a replacement
switch. No one makes a replacement for the 1962 GMC Trucks, they are NOT the same a Chevrolet.
the 1960-61 Trucks used the same set up as 1960-62 Chevy Trucks & 1963-66 GMC used the same as
1963 Chevy trucks. You can find these parts at Classic Parts of America. Some guys have switched
over to a Chevy column & some have used those add on turn switches. They have also used Tilt
column from other Cars & Trucks. I used two toggle switches once to make a temporary repair in
my 1962 Suburban, you just have to remember to turn them off after the turn like you do with the
add on type. I used a 1973 Buick Column in my Suburban & just wired up the lights by trail & error.
I'll list below the three different types of stock GMC set ups used on our trucks, & you can use this
as a guide for troubleshooting or rigging up or switching over to a system of your own that works.
Troubleshooting Turn Signal Systems
Be sure you have checked out your lighting & wiring on your truck before going to this step,
used the links below to make sure your problem in not in the column first. Once you have
check every thing out & narrowed it down to the column wiring or switch, then come to this
page & use the diagrams below for the year of truck you have, 1960-61, 1962 or 1963-66.
The most common problem is that either the brake lights won't work or one side of the other
is not working. Power comes to the signal switch from two places, one from the flasher, the
other from the Brake light switch. If none of the lights flash, check the flasher & fuse. If
you find either one bad replace it. Check go power from the brake light switch with the peddle
depressed. if you have power on both these input them they should be good to the switch.
Stop light power is canceled by the turning switch. If you don't have any brake lights, but have
power to the switch, then You have a bad turn signal switch. If the Turn light works but not the
brake, you can just bypass the turn switch, run a wire to the rear for brake lights & add some
lights for the brakes. this will save you from having to tear apart the steering column. You
replace the switch to get them working again too.
If you find one side or the other of your turn lights not working, & you have check the light &
wiring first and that part if OK, then again you have a bad turn signal switch. You'll need to
replace it with a new one or replace the whole steering column with a know god one from another
truck. If you go this route, you mite as well get a tilt column while your at it. Many Vendors
sell replacement columns. If you pull out your switch, you mite be able to match it to something
that will work, some of the members have done this. As far as we know, no one makes a replacement
for GMC Trucks. They do make one for Chevrolet trucks & you could always swap one of those into a
GMC with out too much trouble.
GMC used one light on the dash for Turn Signals, so if you don't have your front lights working
right, it won't work right. It grounds through the opposite side when the lights are no.
How Its Wired 1960-61
These trucks should have a switch mounted near the bottom of the column with
a cable up to the lever. The switch will have 6 post stacked like a pyramid.
1960-61 Switch/Plug Wiring
Violet is the Right Rear Turn/Brake light.
Dk Blue is the Right Front Turn.
Yellow is the power from the flasher to the switch.
Lt Blue is the Left Front Turn.
Pink is the Left Rear Turn/Brake light.
Natural is Brake light power from the Brake Light switch.
How Its Wired 1962
These trucks should have a switch mounted Under the steering wheel with
the wires come down the inside of the column. There will be a Natural
colored 6 wire plug on the right side of the column.
1962 Trun Signal Plug Wiring
14 Nat. is Brake light power from the Brake Light switch.
16 Violet is the Right Rear Turn/Brake light.
16 Dk Blue is the Right Front Turn.
16 Yellow is the Flasher Power to the switch.
16 Lt Blue if the Left Front Turn.
16 Pink is the Left Rear Turn/Brake light.
There should also be a Dark Green wire running up the column for the Horn.
How Its Wired 1963-66
These trucks should have a switch mounted Under the steering wheel with
the wires come down the inside of the column. There will be a Black colored
8 wire plug on the left side of the column.This plug is curved double row
plug with four post in each row.
1963-66 Trun Signal Plug Wiring
(18-V-16) Violet is the Flasher feed to the switch.
(18-N-17) Natural is the power feed from the Brake Light Switch.
(20-BK-28) Black is the ground from the horn relay to the horn button.
(20-D.BL-15) Dark Blue is the Right Front Turn light.
(20-L.BL-14) Light Blue is the Left Front Turn light.
(10-D.GR-19) Dark Green is the Right Rear Turn/Brake light.
(18-Y-18) Yellow is the Left Rear Turn/Brake light.
(20-GY-8) Gray is the Panel Light used only with Auto trans.
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© 2000-2005 6066 GMC Trucks. Last Updated March 6, 2007.
