70 bronco blinkers and hazards not working

[zachjb95]

I'm working on my 1970 ford bronco that's having a wiring problem I cant figure out. so the issue is the blinkers and hazards don't work. all the other lights work fine .also the front blinkers and blinker indicators on instrument cluster turn on solid when applying the brakes. anyone else encounter this issue or no what's wrong and can help would be much appreciated

 

[Digger556]

With most wiring gremlins, check and re-check all grounds.

For older equipement, this means pulling all grounds, checking, cleaning and reattaching.

 

[swmrdrn]

Check the flasher. Those fail all the time.

 

[DirtDonk]

Hey zach, welcome to classicbroncos.
Is your '70 stock, or has it been modified? Original wiring, or new replacement harness? Original steering column, or replacement?
As said, it's usually a grounding problem (especially on older vehicles like ours) but it can be a couple of issues working together.
As said also, check or replace your two flasher units. They originally had clips to hold them in place, but most times we just find them hanging around under the dash where the last person to work on it left them. But look around and you'll find them.

You can substitute a new one, but with the sad state of new parts being what it is, you can be introducing another factor if you get a bad one right out of the box. Happens way too often unfortunately.
There may be an easy way to test them, but not sure what that is off the top of my head.

For grounds, your truck originally came with only one body related ground. And if your negative battery cable has ever been replaced, it's a bet that the original body ground was not returned to service, so to speak.
So look at your battery's negative cable lug. Should be the main large cable to the engine block of course, but there should be a secondary one running to the fender or wheel well.
In addition to this you should run a secondary ground wire from the fender to the radiator core support because this is where the headlights and turn signals get their grounds. If your headlights are dim, this may fix an issue. If your headlights are already bright, then a bad ground connection up front may not be the issue after all.
But adding extras never hurts anyway.

For the rear lamps, the housings ground through the two screws into the body. If they're all rusty you may need to clean them up a bit.

Also, the bulbs can be bad, but if your brake lights work as expected then the bulbs are still good.
The reason I mentioned new wiring harnesses and steering columns though, is that they often get wired up incorrectly with the turn signal switch and you may have the fronts switched with the rears. The turn signal indicators on the dash are tied into the front turn signal bulbs only. So in theory there's no way for the brake lights to turn on the indicators.
A bad turn signal switch might do this, but it's easier to check and add grounds first.

Good luck.

Paul