1957 headlight switch current division

[Theodore K.]

I am still tracking my headlight problem and am def convinced that it is just overcurrent. Realize the headlamp portion itself but am trying to understand the circuit a little better. Two questions.
1. Does anyone have a schematic for the headlight switch itself? There are two breakers on the switch. Do we know which current load goes to which set of CB points? I have determined that the load for parking lamps, etc are a little over 6 Amps. When you add the headlight currents, it is no wonder that the CB trips.

2. Do the later model headlight switches interchange and have larger breakers.

It was mentioned in one of my other threads to change this over to a relay and simply run the relay. Has someone done this and if so, what relay was used, ratings, etc. It said to fuse appropriatly. What is the fuse rating used. Surge currents on cold filaments can be large. Would a CB be a better choice?

All comments welcomed.
Thanks,
Ted

[Dan D.]

Re: 1957 headlight switch current division

Ted, I did not draw a schematic of the switch when I had mine apart, but it would not be hard to do so. Basically, there are 2 blocks inside the switch that move fore to aft when the switch is activated. I took mine apart to clean it up and fix the rheostat that was corroded to the point that it did not work. The whole switch was badly corroded, but other than to dimmer it worked.

We covered a lot of bases before on your switch problem several months ago, even to the extent of putting stubs in various places to see where the volts go away.

If your lights are still toggling on and off, and you have covered all the logical bases, then perhaps the problem in is the headlight buckets themselves. Its hard to believe s short could occur in them, given that the only ground is through the ground wire and back through the harness, which I believe you have replaced. Have you replaced the bulbs? Possible one is shorting after it heats up. Dan

[Gary C.]

Re: 1957 headlight switch current division

Ted,

Recommend elimination testing. Install a temp proper gauge jumper from the switch to the headlights and bypass everything inbetween. If problem does not reoccur, reconnect the light switch and bypass the next item in the headlight circuit. Repeat until you find the culprit.

JMTCW,

Gary
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[Theodore K.]

Re: 1957 headlight switch current division

Dan, first let me thank you for all the help and thoughts that you have provided over the past year or so of this problem. Let me summarize a few things that I have done.
First, new light switch
Second, new dimmer switch
Third New wiring harness. When installing I carefully looked for any cut, abraded, short prone wiring. Nothing noted.
Fourth, I replaced the headlights themselves. I purposely put in H6024 Halogen. I knew they were higher current draw. They are rated at 5.08A on High and 2.73 on low. Knowing the current draw would tell me if the cutout occured sooner. When I changed them I noted that the removed bulbs were the ones on the car when I bought it in 1983. One was a 6012 and the other was non-legible but was a guide lamp marked with a 2 on the front glass. Under the current circumstances, these lamps would cutout after maybe 10min on high beam and only once in a while on low.

The H6024 lamps cutout in a couple min on high beam and then once that happened, they would cutout on low beam.

I then began to separate the bulbs and measure currents with my DVM. I found that sure enough the H6024 drew the correct current in High and Low with one or two connected. So then I measured the total current draw on the bat lead feeding the light switch. I was somewhat amazed to find that the draw with dash lamps and courtesy lamps on but headlights disonnected was about 6.6 Amps. When added to the headlight load it was easy to see why they cutout and it was indeed an overcurrent trip.

I am still curious why last year after all those years on the old headlights that they started to cutout. That was before the new switch, dimmer switch etc. Now that I have added a courtesy lights to the car the load is a little greater. There are two breakers on the top of the switch and I am curious how that 6 amps is divided up. That is why I wanted to know the switch schematic. I was assuming that the headlights are on one side and all the other lights on the other breaker pair but that does not appear to be the case.

I wish I had a new pair of Guide T3 headlights to compare and test. I may see if anyone has some I can borrow and try. I suspect the T3 current draw is much less. It was suggested last year in one of the threads that the I install a relay to carry the headlight current rather than routing through the switch. That may be the only route to follow. I do like the brightness of the Halogen lights as the dimmer old headlights have always been a problem.

Anyway, any more thoughts are welcome and do appreciate your thoughts already.
Regards,
Ted

[Theodore K.]

Re: 1957 headlight switch current division

Update to previous note..After some circuit tracing I determined that that light switch only puts the headlight current through the circuit breaker and all the other lights go through the other CB. I did find a T-3 Guide lamp which is also a 6013. I am going to pursue the CB again. My previous testing showed that they could take about 15 amps without opening, but tonight I measured the amperage using a pair of H6024 bulbs. They drew about 9.5 amps on HB and the CB opened after about 4 min. The low beams were pulling about 7.5 amps and would run for awhile. This is telling me that the CB in the switch cannot support even 10A nominal without opening. The switch was new last summer and came from Corvette Central. Not a cheap thing either so no rushing to get another one. This is getting more interesting all the time. Makes me think the relay is the way to go. Sad but true. They don't make the old 6012 bulb anymore either so we are kind of between a rock and a hard place.
Ted

[Dan D.]

Re: 1957 headlight switch current division

Ted, this is not making any sense. Why don't you try this;
Put a piece of paper between the CB contacts to isolate them. Put a clip lead on each side of the breaker and bring them out to your current meter. Measure the actual current going through the breaker.

Just because this is a new switch doesn't mean mean it is any good. Lots of bad aftermarket parts out there. If your original switch looks okay, then clean it up and use it.

Also the 6.5 amps you measured for the dash and courtesy lights seems very high. -Dan-

[Theodore K.]

Re: 1957 headlight switch current division

I can try that Dan. I have the old switch and the rheostat is bad and that was one of the reasons I got a new switch, but the main was the headlights cutting out. After tracking the circuit through the switch, it became apparent the headlight breaker set only fused the headlights. I actually measured the headlight current at the dimmer switch and found the CB cutout was only a few min when the current was about 9.5 amps.

The 6.5 amp figure is total current flow through the switch with the headlights disconnected. However, when I put in the new harness, all those bulbs were replaced and I added the courtesy lights. HOwever, the 6.5 amps is going through the other set of CB points and thus is not in the headlight circuit path. I do agree with your comment that a new switch does not guarantee it is any good. This replacement stuff is made who-knows-where. Corvette central was vauge last year on the CB rating when I ask them about the new switch.
Ted

[Dan D.]

Re: 1957 headlight switch current division

Okay Ted. If you can measure the actual breaker current and it is less than 10A, then you should be able to duplicate the cutout using a power supply and load. It is possible that you have 2 bad switches. Perhaps someone here on the forum could lend you an OEM switch just to try.

It should be possible to put your new rheostat on an old switch if push came to shove. I don't know how bad your rheostat is, but I repaired mine. It was just so badly corroded that the rivets, which carry the current, we not making contact anymore. So I cleaned and soldered them. -Dan-

[Theodore K.]

Re: 1957 headlight switch current division

My old rheostat was burned out. YOu can see the burned broken wire on the rheaostat coil. Been that way since I bought the car in 1983. The dashlights were never dimmable before, just fixed on at full power. Yes I would like to try another switch. They are kind of high priced to just keep buying them. I am an electrical engineer and have worked the service business before in two-way radio. Currently I am a EE doing capacitor design and product line support. I live in Nebr but work in Vermont... go figure .. but it works.

Tonight I am going to take my old switch and bypass the old one from the battery and just put the headlight load through it and supply right from the battery. That way I can watch it and see what is happening.
Ted

[Dan D.]

Re: 1957 headlight switch current division

Good idea Ted. See how hot it gets.

If your old switch breaker contacts are corroded, then that will make it run hotter and open prematurely. Have you tried sanding them? Too bad you can't fix it with a new capacitor like you do in work! -Dan-

[Gary C.]

Re: 1957 headlight switch current division

Ted,

1957 T3 headlamps are rated are 45 watts high beam and 35 watts low beam.

The newer H6024 bulbs draw almost twice as much - 60 watts or more depending on the brand.

1957 headlight wiring is 18 and 20 gauge if I read the hard to read wiring charts correctly - 18 gauge from the the headlamp switch to the dimmer switch. 18 gauge should handle 10 amps OK without getting hot.

If you have 60 watts for each headlamp that's right at the maximum current draw for an 18 gauge wire.

I've not been able to locate a headlamp switch blueprint. Would expect with a total T3 headlight draw of 90 watts that the headlamp switch circuit breaker would be rated for 10 amps. Delco Remy D1518 is a 35 amp switch (total amps for connections).

JMTCW,

Gary
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[Theodore K.]

Re: 1957 headlight switch current division

Gary thanks for that info. Do you know what teh Delco Remy D1518 35amp switch was intended for ? ie- what vehicle?
Ted

[Gary C.]

Re: 1957 headlight switch current division

Delco book shows app for 56-7 Corvette

[Adam S.]

Re: 1957 headlight switch current division

Hi Theodore, same exact problem my buddy had with his 1956 Bel air (same switch as 57 corvette) , he put the super brightnewer H6024 bulbs in & a week later his CB on switch was opening up, he found some Gm power beam lamps they worked great, were a little briter than the T3's & did not open the CB. Agree with Gary 100%.

[Theodore K.]

Re: 1957 headlight switch current division

Dan, thanks for the various comments and suggestiions on this thread. Some where in the maze was a suggestion to install a relay to bypass the Circuit breaker and go with a fuzed circuit. Through the many experiments I pretty well concluded that the CB on the new switch from CC was not up to snuff. I doubt if another from them would solve the problem either. I bought a set of Halogens and found that sure enough they added current draw made them cut out sooner. I put the old switch back in a ciruit that came right from the battery to the old Headlight switch and then on to the dimmer. It confirmed that the old CB, after substantial cleaning) would hold the current although the wiring and various connectors got quite warm. After much consideration, and appreciation for the brighter headlights the Halogen's provided, I ordered a relay bypass kit and wired so that the Headlight switch only ran the relay coils and the actual current switching was handled by the 30 amp fuzed line I installed from the battery. I am happy to report that the problem has been corrected. Just got back from a 200 mile trip and ran the headlights for several hours without incident. All the suggestions on the board were very much appreciated. I feel the 57 is safe to drive again.
Ted