1974 c10 turn flasher
 

I’m working on a 74 c10 where the blinkers are not working. I found out after looking way too long that the flasher was getting power to the L terminal and not the X terminal. My question is which location is supposed to have the 12 volts? I’m wondering if the wiring is messed up somewhere. I’ve attached a photo and outlined the flasher location with yellow.

Re: 1974 c10 turn flasher
 

The flasher is a switch so it should only have voltage on one side. You can swap the 4-way flasher to test things if the 4-ways are working.

Re: 1974 c10 turn flasher
 

The pin on the left is the one with 12 volts which is the L terminal on my flasher. If I take the flasher out and turn it so the L terminal is now on the lower right and then apply 12 volts with a power probe to the X terminal it starts working, however the X terminal does not fit into the fuse block when turned that way. IÂ’m not sure if that makes sense. Im wondering which one is supposed to have 12 volts, the left side or the right side?

Re: 1974 c10 turn flasher
 

I don't know what the X or L terminals are. The fuse block isn't labeled. All the flashers I've seen have 2 terminals and only plug in one way.
Nobody rewired the fuse block or the flasher so they are as GM intended. I don't know what your point is.

Re: 1974 c10 turn flasher
 

I tested my 75 model and it appears to be the same as yours.

With the ignition switch turned to RUN the far left signal stat female terminal has 12 volts.

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Re: 1974 c10 turn flasher
 

Thank you for checking yours. That helps.

Re: 1974 c10 turn flasher
 

The X and L terminals are labeled on the flasher itself. I was trying to figure out if something was rewired incorrectly or if there was a separate issue. I agree that it only goes one way and they are all wired the same. That was part of why I was confused. Thanks for your input.

Re: 1974 c10 turn flasher
 

Do you get the same no-op result with the hazard flashers?

As a test, use a wire to jump the fuse box hazard terminals. All your turn/brake bulbs should light up when you activate the hazard switch.

Same for turn signal bulbs.

Of course, with no flash unit, the bulbs should be on full time.

Looks like a lot of corrosion in that fuse panel. Pull the fuses, clean the contacts and reinstall the fuses. Might be that simple.

Re: 1974 c10 turn flasher
 

The picture is not actually the fuse block I’m working on. It was just so I could high light the area in question. The question is out of those two terminals which one has 12 volts?

To answer your question the hazards work fine. I got everything to work in the end. I just want it to work correctly. I ended up using a headlamp connector on the flasher and then running the wires from the connector to the fuse block in the opposite then the flasher would normally plug in.

So I’m trying to figure out why it works that way. Is the wiring messed up, do I have the wrong flasher, etc.

Re: 1974 c10 turn flasher
 

What type of flasher are you using?

The original style electromechanical flashers will still work if the terminals are reversed. However, it sounds as though you may be using an electronic flasher which needs power supplied to it's X terminal and the load to be on it's L terminal.

A couple common ways you could fix this: (1) Unscrew the fuse box from the firewall, pull it out, and separate it from the inner half of the bulkhead connector. That will give you access to the back of the fuse panel and allow you to extract the terminals from the turn signal flasher socket section and switch their positions. (2) Buy a 'reverse polarity adapter' ... They're a little round disk that plugs in between the flasher and socket to reverse the connections (basically just a more compact version of the fix you're already using).

Re: 1974 c10 turn flasher
 

Thanks for the info. Can you still get the original style flasher? The only I got was from autozone. It’s still a 552 flasher but it’s a lot bigger so I’m getting there is a circuit board in there. I pulled apart the fuse block when I fist discovered it and was going to swap the wires as you described but the terminal that has 12 volts is getting it via a jumper wire from another terminal from a different slot.

Re: 1974 c10 turn flasher
 

Yes, I believe the original electromechanical type flashers are still available. Although I don't think you can go by the part number alone because a quick web search of '552 flasher' showed up lots of variations (some of which had transparent covers that made their electronic internals clearly visible).

The jumper wire feeding 12V to the flasher socket shouldn't present any issues with swapping the terminals (unless it's physically too short to reach). In other words, just swap the terminals between the two cavities in the fuse block housing (leaving their wires attached as-is).

Re: 1974 c10 turn flasher
 

Awesome, thank you.

Re: 1974 c10 turn flasher
 

If memory serves me the turn signal flasher was part # 323 and the emergency flasher was part # 552. My 1996 Regal even uses those same flashers.

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Re: 1974 c10 turn flasher
 

I’ll have to look into that. Thank you

Re: 1974 c10 turn flasher
 

The 323 flasher should look like this picture.

The problem is that most 323 flashers will flash at different rates. It would be best to go to a salvage yard and get a hand full and see which one flashes the way you want.