Just remember -- restoring a bigger truck is not for the feint of heart, weak of arm or small of garage.
It seems so simple. It seems so common. But ahhh ... not for those trucks made before 1954. Turn signals were not a factory option. It wasn't until 1960 that they became just that - an option! Back "in those days" folks were still using hand signals. So, here we've got some help for those who have "updated" their old Bolt so they can keep their hands on the wheel.
A most common question
This seems to be one of the most common questions concerning these old trucks. Prior to 1954, turn signals were not a factory option. Until 1960, they were still just that -- an option. Back in those days, the hand signal was used. It served its purpose back then but nowadays most people would have no idea what you were signaling. So among the current safety items we add to our trucks, turn signals are near the top of the list.
There are several types and brands of aftermarket switches available and many of our old trucks have been outfitted with them already. But if your's hasn't, here are some tips to guide you through it.
One of the most popular brands is Signal-Stat. You can find wiring diagrams for several models of them on the web by typing “Signal-Stat” into your favorite search engine.
There are three types of turn signal switches. The basic unit uses a separate set of lights while another type uses the same lights the brake lights use. The third type uses the brake lights and also incorporates an emergency flasher.
WIRING THE BASIC UNIT
These units have five wires and are the simplest to wire up. The example I’ll use is a Signal-Stat Model 700.
As previously stated, this unit uses separate lights from your brake light units so you will have to acquire some lights and figure out where you want them mounted. There are many variations on that so I won’t go into that. For the front signals, the parking light sockets can be converted for two-filament bulbs using kits available from most vendors. On many trucks, you’ll see turn lights bolted to the top side of the front fenders (like the picture at the top of the page).
There are five wires on the Signal-Stat Model 700:
It will use a two terminal flasher. I recommend fusing the system. Pick up an in-line fuse holder and a 5-amp fuse when you buy your flasher.
Note: Disconnect the battery before wiring.
You need to figure a way to mount your flasher. It can be as simple as taping it to your steering column out of view, or you can use a flasher bracket from a donor vehicle.
Run the in-line fuse wire from the accessory terminal of the ignition switch to the (+) side of the flasher. Connect the Yellow wire from the switch to the (–) side of the flasher. Run wires from the switch to the individual lights using the colors listed above.
Be sure your light units are well grounded. It’s as simple as that. Hook up the battery and check your work. Aren’t you proud of yourself?
WIRING A COMBINATION LIGHT UNIT
For want of a better name, I’ll call it that. This unit uses the brake lights for signaling turns. When engaged, it sends power from the flasher to one brake light and power from the brake light switch to the other brake light.
My example is the Signal-Stat Model 900. To use this one, you folks with older trucks will have to add a tail / brake light assembly on the right and convert your front parking lights as mentioned above.
There are seven wires on the Signal-Stat Model 900:
It will use a three terminal flasher and, again, I recommend fusing it.
Note: Disconnect the battery before wiring.
This one is a little harder to wire but nothing a Stovebolter can’t handle. You already have a wire from the brake light switch to the left rear brake light. You’ll need to cut this wire near the brake light switch. Splice a new wire from the cut brake light switch wire to the Gray / Black wire of your signal switch. Splice a wire from the cut brake line wire to the Gray wire of the signal switch. Run a new wire from the Black wire of the signal switch to the right brake light.
(Note: If your truck had a right tail / brake light from the factory but no turn signals there will be two wires from the left light to the right. The one for the brake light will have to be cut and terminated. Leave the taillights connected to each other.)
Run the wires to the front lights following the color code. Run the in-line fuse wire from the accessory terminal of the ignition switch to the (+) side of the flasher. Connect the Yellow and Blue wires of the signal switch to the (L) and (P) terminals, respectively, of the flasher.
Make sure your light assemblies are all well grounded. You should be all wired and ready for a test run. Hook up the battery and check it out.
If your truck is a Task Force (1955.5-1959) or later, you have a place for indicator lights in your instrument panel. These can be wired in using instrument light sockets from a parts truck wired to the front signal wires.
WHAT IF I CAN'T FIND A WIRING DIAGRAM?That's a very good question and I'm glad you asked it. As I said earlier, there are several brands of after market switches available. For many of them you won't be able to find the wiring diagram. That's the problem I had with the factory switch for my 1954 GMC. So I used the following method to find out just which wire goes where.
You'll need an ohm meter for checking continuity and a pencil and pad for writing what you find. It makes it easier if you have alligator clips for your meter. You need a grid to chart your findings on. I used a lined legal pad and drew vertical lines to make as many boxes as I had wires. Then I labeled the grid with the wire colors. It looks like this.
A switch that hasn't been used in a while is bound to have some corrosion, cobwebs and cooties on the contacts. So before you start checking, cycle your switch from left to right several times to help assure good continuity.
Now with the switch in the off position, clip your ohm meter lead to the first wire and check for continuity with each other wire. When you find continuity, place an X in that wire's square. After checking each wire, move your lead to the next wire and again check each other wire. Mark your findings on your chart. Repeat until you have checked each wire to all the others. When I finished, my chart looked like this:
Now put your switch in the left turn position and make another chart. Check each wire to the others and find where you have continuity in this configuration. Mark it on your chart.
Now go to the right
turn position and make a chart for it. My finished charts looked like this:
OK, now it's time to put your powers of reasoning and deduction to work. Let's see if we can figure this out. The first thing we take into account is the fact that only the brake lights work when the switch is off. Looking at the "OFF" chart we see that pink, white and black all have continuity. From this we can deduce that one is from the brake light switch and the other two go to the brake lights. But which is which?
Let's have a look at that chart for the left position. In it we see that, of the three wires in question, only the white and black have continuity here. AHA. With our powers of deduction we now know one of these is the power from the brake light switch and the other is to the right brake light. How do we know it's the right brake light? It's the one on when the left side is flashing.
Now let's look at that right position chart. Here we see that white and pink have continuity. AHA again. The white one has to be the one giving the power and the pink one is the left brake light. That makes the black one the right brake light.
OK, we have the brake lights figured out. What about the turn lights? Well let's study those charts some more. We already know the left brake light is pink and the right one is black. So when the left signal is on something is sending power to the pink wire. Looking at the chart we see it's the yellow wire. And what is that yellow wire doing with the switch in the right position? Why it's sending power to the black wire. But wait, it's also sending power to the dark blue wire. Using our reasoning powers, we know that has to be the right front signal. And looking back at the left position chart, we see that yellow is also sending power to the light blue wire in that position so that is the left front signal.
Alright! We've got this figured out.
This system uses a two terminal flasher. I'm really not sure what your chart would look like if your's uses a three terminal flasher. I don't have one to wring out. I obtained the colors for the Signal-Stat Model 900 from an on-line diagram. The difference will be one more wire for the flasher. But if you chart it out like I showed you, you should be able to use those powers of reasoning and deduction to figure it out. This electrical stuff is easy if you just think about it.
One more thing before I go. That 1954 GMC turn signal switch will work on your 1954-55 Chevy and vice versa. You might be able to make it fit your 1953 and older column, too. If anyone does, let us know in the forums. When you find one in a wrecking yard, be sure to also get the canceling bracket off the steering wheel while you're there. The same switch was used on the second series 1955 GMCs for sure and possibly even later.
Good luck and happy Stovebolting!
You can contact Cletis in the forums. He is the moderator of General Truck Forum. ~ Editor
Update Feb 08