Last Thursday my brake lights stopped working. I test the circuit- with the brake light switch engaged, I had power to both sides of the switch, power at the wire when disconnected from the socket, but as soon as I connected the wire to the hot lead for the brake light the voltage dropped to ZERO. So I ran new wires to and from the brake light switch, installed new sockets, and got new bulbs. Everything is brand new. But I still have the same exact problem. CAN SOMEBODY PLEASE TELL ME WHERE THIS BLACK MAGIC COMES FROM!!?? Thanks in advance to whoever might hold the answer to my dilemma!
All I can tell you is the problem must lie in some place other than what you've changed keep looking you'll find it
It is in my '53 Clipper. I didn't even think about it, but I bet it is supposed to go through the turn signal as you suggested.... makes sense now that I think about it. When I ran new wires I bypassed the turn signals. This should still allow the brake lights to come on? I not an electrician by any means though. Also, I discovered that the HOT wire from the socket for the brake light is acting like a ground for the TAIL light when it touches the body. As far as I know the leads for the brake and tail lights should be totally separate. I thought this was a short in the old socket, but I have the same problem with the new socket and new bulb... Why is this? -the bulbs I am using are 1154 dual filament.
I may have a wire diagram for that car. I can look tomorrow at the shop. That kind of sounds like feedback caused by a bad ground at the sockets?? Like was mentioned by another poster above.
Thanks for all the help guys!! I've run out of daylight for today, but tomorrow I'm gonna test the grounds in shop class. The tail lights work, so i figured the ground was ok. But like I said, I'm no electrician. I'll let you guys know what I find.
maybe a ground problem... this happens all the time on our tow trucks it gets real tricky when you throw a led bulb in the loop b/c of less voltage to the bulb
On the older cars, the socket grounds both filaments. If the socket is not snapped in place then there is no ground. If you have voltage at the switch, but lose the voltage when the circuit is connected then you have a loose connection somewhere on the power side. This could be at the fuse. Feel the wiring and fuseholder, a loose connection will usually build up heat.
So, I installed a new brake light switch, ran new wires, re-did all the connections, got another new socket and new bulbs, checked the ground and also ran a redundant ground just to be sure.... it's still is doing the same thing though!! I had all the guys at my mom's work lookin at it today, and they we're scratching their heads too. Any ideas?
explain the problem again, you have power at the tail light until you connect the wire and then the voltage drops to zero?
Quit having people that have no bussiness looking at your simple electrical problem mess around with it.Put a turnsignal assy switch in and get on with your day.Your signal switch allows the brake lights to work when they are activated.Very common problem that is often overlooked.Dan
Have you tried running a separate power wire from the battery to the brake light switch to eliminate the power side? You can also move down the circuit towards the brake lights to see if and when they work. A power probe test tool makes this much easier if you can get your hands on one. They are a life saver!
I tried running a wire direct from the battery to the brake light switch for power, and the same problem occurs. There is power at the wire from the brake light switch until a connection is made to the light socket. Then the voltage drops from 6 volts to 0 volts. rouye56wingnut- I mean no offense to you by this, but the guys that looked at it had plenty of business doing so. They are all mechanics at one of the more reputable shops in the area. Is there a relay or something with the turn signal switch that lets the brake lights come on? I thought if I bypassed it, it wouldn't matter. It has the same problem no matter if I bypass everything or use the original circuit, Could this be a bad turn signal switch then?? On that note, I have a few old turn signals, the kind that clamp around the column, would using one of these possibly solve the issue?
Correct, kind of.... the turn signal switch does act like a relay in a sense that it directs the power to the brake lights correctly. When you turn the right signal on and press the brakes, the left brake light will stay on while the right will blink. The opposite will happen when the left signal is on. If you were experiencing this issue with power going to the turn signal from the brake switch, then you may want to look at the turn signal switch as the issue.
Not sure about all of the add on type turn signal switches, the one I used to have had no provision for brake light wiring. It does sound like the problem is going to be in the turn signal switch though. Everything else has been checked out or replaced.
this is a 57 it should be close. Try using a test light, I have wired hundreds of cars and a light circuit is the simplest one to do. If you have power on both sides of the switch when it is applied it doesn't disappear at the socket. It should go through a filament and then to ground. If it went straight to ground the wire would burn or a fuse would pop.
99.9% of wiring problems are ground problems, run a temporary new ground from your new socket directly to the - neg post on the battery and check it
Take all 4 signal bulbs out of the sockets,front and rear, turn on the offending lights, and use a test light in the socket ,ground one side of the test light and probe the other end on the contact inside your tail lamp socket . If all works good,on each side you have the wrong bulbs or a bulb with a shorted filament. A bulb with a shorted filament is like chasing a rabbit,testing this way take the gremlin out of the mystery!
I wouldn't go that far, maybe 75% at best. With these older cars, corroded terminals, contacts and wires are also easy to blame and many times overlooked. Heck I had two corroded terminals on my daily driver that prevented my push button 4x4 to engage and it's only an '03 and from what I've researched a common occurence for that make and model vehicle.
Try this diagram. May be the same. Does look like the turn switch could be the culpret. You should be able to just bypass the switch all together to test it. Hope this helps.http://www.tocmp.com/tOCMP/wiring/5765wiring%20diagrams/Studebaker/MWire5765-381.jpg
A lot of good suggestions have been made, you need to test the system correctly.\But ONE thing has NOT been mentioned...if you used a "new" socket from the auto parts store, on the HELP rack, and used a "new" bulb, probably from China, the problem might still be there. I've put some of these on older cars, and the sloppiness of the manufacturing can cause big time, hard to find problems. Between the clearances of the socket, and the bulbs not made just right, you can have the one terminal of the bulb crossing the 2 terminals on the socket. Or the terminals might not be making contact, I've even found where the bulb's 2 electrodes are crossed inside the bulb! My bet would probably be in the directional switch, but proper diagnostics are the key to finding the problem!
Grounds are not the problem. A good ground pulls the voltage to zero. A bad ground will leave the voltage up. Use all the new wiring you have mentioned. BYPASS the brake light switch. Make sure nothing is going through the direction light switch. See if the brake light lights. Going by your description, about the only thing that could cause what you describe is a high resistance contact inside the switch as long as your new wires are direct and not through any old connections anywhere.. You don't mention a new switch.
Pull the fuse out of the holder, make sure the end of the fuse is still intack. Will get you every time.
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