Headlights, hazards, interior light problems

Bought a 1973 Sunday needed the headlights replaced, did it tonight. Heres whats happening the best I can explain. When I turn the headlights on the hazards Slightly fade on and out. Also the dash speedo light fades on and out. When I turn the interior lights on its hit or miss as the headlight knob turns completely around. When I press the accelerator pedal the above issues react at the same time. The light problems occur without the pedal being pressed also.

I know very little , so any details on what to look for would be GREATLY appreciated.

Thanks a lot ed

a few thoughts on this - lights fading means:
alternator not keeping up with load OR
voltage regulator not doing it's job OR


i re-read the question: are you saying that when you turn your headlights on, then the hazards are magically fading on and then dying?

yes, fronts only. No reaction from any rear lights. Theres no consistently, they are very faint to coming on a little more bright to off completely. It seems the dash lights are doing the same, of course its hard to tell if at the same time.

Maybe there aliens near by

eds73 said:

Maybe there aliens near by

Click to expand...

Usually, if it seems like aliens are near by, or your Bronco has been posessed, it's a grounding problem. It might be worthwhile to verify your grounding scheme. A pretty standard grounding scheme will have the battery negative cable bolted to the engine block. Then a ground wire from the block to the body somewhere. Quite often this connection is made from the rear of the intake manifold to the firewall. Then one last ground wire from the engine block to the frame.

The 'ground wire' I mentioned is usually a braided strap. I've seen them in the Help section of most auto parts stores, and also in the section with all the generic battery cables.

Check into a separate headlight harness. You can do a search on here on " headlight wiring harness". One problem that WILL arise is that, eventually, your headlights will begin to flicker or cut out altogether-intermittently anyway. The Bronco's headlights receive a reduced voltage (I want to say 6 V); there is a component in the stock headlight harness that reduces the voltage from 12 to 6 V--dont remember what the component is called. Eventually, this component starts to go south and gets hot, it cuts out and you lose your lights. This can be circumvented by going to a separate headlight harness that runs right off the battery with a relay. When the lights are on, the relay is tripped--using the signal from the stock headlight wiring, however, there is not the draw on the stock wiring that the headlights put on the system, so it doesnt heat up the same way and fail-- and you receive the full 12V from the battery...MUCH improved lighting even with stock lamp assemblies...if you also upgrade to H-4 assmblies, your lights will be as good as anything on the road today.

Not saying this is something you should do NOW, but something to put on the "Hey, its easy to do" and "One more thing I wont have to worry about" lists. I have been on several road trips in years past, in the middle of nowhere, and had my headlights cut out or in/out-repeat infinitum. Some claim that changing the headlight switch or dimmer switch will fix this problem, but it always returned fo me--in relatively short order--until I went to the headlight harness. That with the H-4 assemblies and quality bulbs are very impressive. Good luck.

John

Check your grounds you may even need to add one sometimes people remove them and dont put them back on. The seperate headlight harness/relay is a good idea but you will still have problems with the hazards if your grounds are bad.

All of those apply, but absolutely change your headlight switch. You said it just turns round and round and does not have the desired effect on the dash lights. So you know for sure that at least part of the switch is bad. So that's a must-do in my book.
And even though what you describe is not usually due to anything in the floor mounted dimmer switch, those things take a good beating and get pretty corroded and dirty inside. They're cheap too, so it would not hurt to change that out as well.

And as mentioned, grounds, grounds, grounds. Check 'em all.

When you say the flashers come on, then go out, are they actually flashing at first? Are they bright, like the blinkers or the flashers? Or is it just that the amber running ligts come on and then fade out? Is it only when you've switched the hazzard switch on first? Or does it come on all of it's own accord?

Paul

Paul