'56 F-600


I'm having some trouble getting my brake lights bright enough. I know they can be much brighter than they are, the front turn signals are way brighter.

I tried replacing the bulbs and even replacing the whole unit (1034 bulb originally, using a 2057 in the new unit) but they are still dim, very dim.

At first I thought that maybe the problem was the wiring, so I connected the tail light directly to the battery to see what they could do, but they didn't get any brighter, which struck me as very odd. The battery is good, it's new, though I've been using it as I work I was still able to start the truck up easily after testing today. I'm just not sure why they are not getting any brighter.

I'm thinking it might be a combination of things, something on the lines going out not getting enough power and perhaps something that regulates the power after the battery (haven't looked into this, but it seems very odd that hooking it up directly to the battery produced such poor results, so I'm thinking I'm missing something that maybe ups the flow or something. I thought I understood auto electrical pretty well till I managed to get my front blinker to work with only one wire of the two plugged in). I tested it with the truck running too and found no difference.


Any ideas? They're just barely lite up, enough where even with the cover off I could look right at it and make out the filament, almost orange instead of yellow or white in color when on.

Also, my brake lights don't seem to kick in till the pedal is way down, I had them working before I looked a the blinkers, frankly they're so dim right now that I can't tell if they still are or if I fuddled. I still have a loose negative wire that was with the front left blinker 4-way port, but it caused the blinker to remain solid until the battery was removed, no idea where it actually goes, but this shouldn't have effected how bright the rear got in anyway.
Thanks

 

Sounds like a grounding issue. Check for corrosion between the socket and housing, tail light bracket and body, body and frame, frame and battery. You can run a ground wire to the socket from the battery first to see if that will fix it.
brian...

 

I will second grounding, as I once had a similar problem. The bulb and socket are grounded through the lamp housing and bracket to the frame.

Here is a quick test - Get some sandpaper or a scraper and clean an area on the lamp housing down to shiny metal. Do the same to a spot on the frame. With the brake lights on, (I use a snow brush wedged between the seat and the brake pedal), touch the ends of a wire to both shiny spots. If the bulb brightens up, it is a ground problem, if not, it is probably a corroded connection in the wiring to the lamp.

Here is something else I have seen. if brake lights are dim, but tail (running) lights are bright, the wires are reversed, powering the wrong filiments.

Good luck.

 

Thanks, I'll test that out.

The lamps I'm using are brand new, I didn't think they would have to be grounded directly, I suppose I should run a wire from the frame to the lamps then? (I imagine attach it bolt that attaches to the lamp?) Seems like it would be difficult to ground something without a wire that was attached to a bracket, that was attached to the bed, that was on the frame but had wood shims under it...

Would this have effected the bulbs not really working when I put it directly to the battery though?

 

I checked the lights and found my parking lights to be brighter, so it looks like I have them flipped (though I'm not sure how that happened)

Also found that loose black wire to be for a dome light, which I don't have.

 

Check that the grounds are clean and solid a dedicated ground wire from light mounting stud to fram wouldn't hurt. Remember that if your light brackets are mounted to a painted stake pocket, the ground will be weak);

Check to make sure you don't have a splice or crimp that is over crunched and has cut the wire (so there are only one or two strands of the copper left;

Check to make sure all your bullet connections are clean and rust free; and,

Try 1176s.

 

As for your brake lights not coming on until the pedal is way down, that's normal for a hydraulic type brake light switch. Most of the usual vendors sell a low pressure hydraulic brake light switch that will make up sooner and under less pressure. That might help. Ultimately, I prefer mechanical switches actuated by the pedal. There are several universal types with adjustable arms and brackets available if you decide to try that.

 

Thanks for the help

I ran a decicated ground on each, didn't seem to help, least noticably, however I tried flipping the wires and that worked. No idea how they switched down the line cause I matched up everything and traced it as far in as I could, but it works, so do my running lights.

I may have to look into the brake switch, I cleaned up the connections today, since I need to rebleed it though I think it might account for having troubles right now, they worked when I had it bleed earlier. A mechanical switch might not be a bad idea, I'm not too thrilled on having to have the brakes all the way on before I get any lights.


Thanks for the help!

 

I just got through a brake light problem myself. As was mentioned, by blueovalrage, the in line hydraulic brake light switches burn out and as they do the current running through them is reduced dimming your bulb. Then they fail. I just ordered a mechanical switch which is designed for through the floor brake pedels. It makes more sense unless you like bleeding your brakes and replacing the switch on a regular basis. Source is www. watsons-streetworks.com. It's about $20.00. Hope this helps.

 

The stock brake light switches work off th epressure your master cylinder creates. If your brakes need to be bled - iow youhave air in the line which will compress - the MC may not be able to create and maintain enough pressure to push the switch.

Also, brake systems are notorious for absorbing water. This will cause rust and gums to form in the system. When this happens, the brake light switch is usually the first thing to get sticky or not flow as freely as it should.

They aren't expensive or hard to replace - I'd just do that.

 

Yes, the pressure from the brake line activates the switch. It forces two small contacts closer together until the current arches across allowing the power to the brake light. The problem is the carbon build up from repeated arching will eventually stop the current from flowing and the switch is dead. If you replace it, it will fail again.

 

Thanks for the imput, I ordered a mechanical switch last night from Mid-Fifty, I really didn't like my brake lights not working unless I was giving it all I had.