Turn signal flasher

[GMCTom]

Come back from the work shop
Unfortunately our exercise was not successful. Changed the brown and violet terminals on the fuse panel to connect the flasher in the right order but no change.
Probably the T/S switch is faulty.

[AZKen]

Give me some time to think on this now.

[FetchMeAPepsi]

if this is still about the flasher (lots of pages here) then it might not be getting enough amps to flash due to grounding, etc. You might try an electronic flasher to test and see if that's the problem. They're cheap and they work with very little amps.

[AZKen]

First to settle the fuse box wiring. You did have the flasher section wired the same as the original box. So it was correct? But something does not make sense. The diagram shows looking at the front of the box. The diagram has the box laying sideways from how it would be mounted in truck. The top is at the left in the diagram. So when box is mounted, the flasher would be at the bottom right. As you look at box flasher receptacle contacts when box is mounted, "L" will be a bit upper right and blade is vertical, "X" will be a bit lower left and blade horizontal. Flasher will not plug in correctly as I believe is what you discovered. So it means the diagram is wrong and VIO and BRN must be switched at box. This is almost impossible to believe, but if we are sure that "L" goes to T/S switch VIO and "X" is a switched hot wire, probably BRN. we can maintain sanity. I would like to see a pic of front of box, as would be mounted, with flasher removed, to see blade orientation of box flasher contacts to see if I'm crazy or not.

You did test the flasher I think. If you agree on the above statements and after you have all the lights actually installed on the truck as original, we will begin testing for where the failure is. Do not install any lenses. Be sure you have all the necessary ground straps. Battery negative cable to motor, motor strap to frame, frame straps to cab and bed. In any order you wish. Be sure there is no paint or corrosion at ground points. Be sure all lamp sockets and housings are grounded. Leave the turn signal switch exposed. Install headlight switch.( I believe it needs it's frame to be grounded). Put in all fuses and leave fuse box accessible but wired. Leave the T/S switch side of the connector contacts exposed without shell like you have it. If the truck is not together, at least put the bed on so as to wire the tail lights properly. We can mock up front turn signal hood lights, but they must be wired into the truck per original wiring. Wiring is usually done when truck is almost complete. One of the last things. You may be too early. We can no longer test with so many loose and temporary parts, grounds, wires, terminations and splices. You can't really mock up wiring. You need truck all together to get all terminations done, routing, dressing, clamping and lengths of wire, switches and gauges wired and so on. You don't save time or work with disassembled mock up wiring testing.

Whatever part or bulb or fuse is bad, a miswire or lack of grounding, we will find it. We will begin testing when all above is settled and agreed.
It would be very nice to have one of THESE

A complete restoration with new paint, a DIY wiring harness with Austrian rules and truck not fully assembled is a little more difficult to troubleshoot than someone who has a lighting issue. I am enjoying the challenge and you just want to drive the dam thing
I am going as fast as I can. You are great and have done a good wiring job. It's tuff for me and you at 5,871 miles away.

Remember we have an 8 hour time difference.

[GMCTom]

OK, lets start. The flasher section was wired according to the original diagram.
Violet > horizontal, brown > vertical. Yesterday I added two wires on the fuse panel to connect the flasher in the right order (X > brown, L > violet).

Without these two wires the only way to connect the flasher is with X > violet and L > brown. Please see the photos. (Small note: I think it is a aftermarked flasher. Yesterday I saw in an online shop that there are polarity adapter for turn signal relays)

Further note: when I test the voltage on the brown wire/terminal of the fuse box, where the X of the flasher should go in, I have 12V on my multimeter with ignition on.







I would suggest we do as you say. I get the truck ready, route all the wiring, etc. and then we continue with troubleshooting. In the meantime, I'll leave the T/S switch disassembled. But I think it will be in the area of April because I still have to paint the back fenders and mount the whole bed. Is that OK for you?

One question: how do you feel about the T/S switch? Can this be defective?

@Pepsi: I think it's worth a try

[AZKen]

Looking at your pics just now, on the back side of box, if the VIO goes out to the T/S switch and BRN goes out to IGN sw, why can't you swap those two inside the box and then plug in the flasher? It will all be correct, right? Yes it will, do that.
I wanted to see a pic of front of box with nothing plugged into the flasher contacts. Please answer faster, I need to go to bed soon.

Your other question: Anything can be defective or mis wired. That is what we will find out in April.
The BRN wire coming into the box should have 12V with IGN on. Yes.

[GMCTom]

Originally Posted by AZKen

Looking at your pics just now, on the back side of box, if the VIO goes out to the T/S switch and BRN goes out to IGN sw, why can't you swap those two inside the box and then plug in the flasher? It will all be correct, right? I wanted to see a pic of front of box with nothing plugged into the flasher contacts. Please answer faster, I need to go to bed soon.

I can swap those two wires inside the box and everything is rigth to put in the flasher but yesterday it was faster to add the two wires for testing.
I can post a photo with nothing plugged into in the evening. My truck is miles away ath the moment.

Your other question: Anything can be defective or mis wired. That is what we will find out in April.
The BRN wire coming into the box should have 12V with IGN on. Yes.

Blue color

[AZKen]

The whole problem was the diagram is wrong and has been wrong for 60 years. I added X and L to the pic. Hope I'm right.
see you in April

[GMCTom]

Originally Posted by AZKen

The whole problem was the diagram is wrong and has been wrong for 60 years. I added X and L to the pic. Hope I'm right.
see you in April

See you Ken and

[GMCTom]

Good morning, Gentlemen

(nearly) EVERYTHING WORKS!!

Brake lights working, turn signal front/back and left/right is also working!

Problem was the turn signal switch. My solution was to buy a Chevy T/S switch (64-66) and change the T/S switch housing also in a Chevy C10 housing. It fits on the steering column without a problem. Colors of the wires from the Chevy T/S switch are also like the original one from GMC. The only drop of bitterness is the quality of the Chevy T/S switch housing. GMC housing material is as twice as thick > heavy duty
But with the result I can live very good

I'll start a new thread (in the next 2 or 3 weeks) with pictures showing the rebuild of the T/S switch and housing using Chevy parts. Maybe it's interesting for some other people with this problem.

The flasher is also working! Ken you are right with your test. It doesn't matter if the X is connected to the brown or violet wire. Also the L.

Many thanks to everyone for helping. Especially Ken

Forgot: last electrical problem to solve is the instrument cluster. On the round connector the voltage is ok on every single pin but on the cluster I have no signal (turn signal, ignition, etc.). Maybe the bulbs are the problem. I will test it the next days.