Technical Brake light switch melted

What would cause my brake light switch to melt?
This is a switch for a ‘60 GMC that I used on my ‘54 Country Squire to get rid of the pressure switch.

The car is 12v with two 1157 bulbs for the stop/tail lights.

The switch is an Airtex/Wells 1s5238,
Same switch in 1970 so it must be able to handle 12v




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Was it new?
Things do get old and wear out,, you don't seem to be pushing a bunch of amperage.
And there is the origin of manufacturing possibility

 

How about a short in the brake lights (or wiring going to them) drawing too much current through the switch?

Charlie Stephens

 

I'd say it's a faulty switch as well. Any issue's when the vehicle had the pressure switch?

 

That's for the fuse to sort out.

 

Melted either excessive current or resistance. I would put an ammeter across the two terminals, brake lights will come on and see what current is (should be the total current rating of the lights). Two 1157s then 2 amps would be normal (max). If high, troubleshoot bulbs, sockets, wiring.
Replace with a better switch, especially if you may some day put a trailer socket on it.

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Could be a problem in the turn signal circuit as the brake lights go through the turn signals. Use the switch to operate a relay. Put a fuse in line with the switch.

 

Heat comes from resistance, not from voltage. If it got hot, it's because there was either excessive current draw for the switch to handle, or there was excessive resistance in the switch. I'm betting on the latter. Put a new switch in and I bet all is well.

 

I burnt up several of those cheap plastic switches so now I use switches for 55 chevy car. Never had any problems with the 55 type

 

Thanks, it was a new switch, but a cheap one.
I have a spare so I’ll try that and check the amp draw.
Time to look for an nos switch, probably one from a junk yard would be bette than what you can buy in the store


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There is your correct answer. Check for a short in the wiring to the brake lights or corrosion in the lights themselves that causes resistance. As he said it isn't "volts" it is the amps that are drawn by the circuit.
You don't have high draw bulbs so there is no reason to use a relay that will just blow the relay or cause the spot that is shorted to burn up. That might make the trouble spot easier to find though.
If you aren't having problems with the turn signals I would think the issue is between the brake switch and the turn signal switch. If you were having pressure switch issues before the problem was probably there before you changed switches even though for me Ford Pressure switches have a lot higher failure rate. My guess there is that the new master cylinder doesn't have provisions for a pressure switch though.

 

pedal not returning to complete shut off

 

Another thing to check is something causing the pedal to stick. Those are light duty, momentary contact switches. If the pedal sticks, the constant current can overheat the switch.

 

It could have stuck in the closed position after you released the brake pedal constant draw exceeding normal brake cycle, heat resistance, but not enough load to pop the fuse. What amp fuse did you have in the circuit? I have 3 55 watt halogen bulbs in my six volt system. They shared power through the cars lighting system switch with a built in fuse. With head lamps on, extended brake application would melt not blow the 30amp fuse. So l ran a dedicated fused power to the switch from the battery side of the solenoid through an inline 25 amp fuse with 12 gauge wire, no problems since. This with a new hydraulic switch with the rewire.

 

^^What he said^^
Wire in a relay and the switch has very light duty (No pun intended) and is not stressed. Any Tinker Toy switch will last forever this way. The relay is much more robust and can handle it.
A lot of directly wired switches fail over time but if yours failed somewhat quickly, it could mean something else is also wacky.

 

Cheap,switch. You should be able to find a name brand to us as direct replacement

 

Collect an OEM one from the junkyard or find a NOS from eBay; either will probably last forever. The new ones are pretty cheap both mechanically and electrically.

 

Thanks for all the advice.
I think I found the problem, cheap switch and one of the push on connectors was loose probably causing the switch to heat up.

I had another switch and picked up a spare, one was made in Mexico and one in Taiwan. The switch that melted was Taiwan so I’m trying the Mexican switch this time.

Meter shows 4 amps. I would think the switch should be able to handle that.

Rock auto has an acdelco switch for $14 I’ll add to my next order, but I’ll also look for an nos switch.



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I would also clean up the grounding for the taillights. That can get cruddy over time, or perhaps you just painted the trunk and now don't have good metal-to-metal contact.

 

Follow up,
I did a little digging on the rockauto website and found some better switches.

Beck/arnley 2010783 is for an ‘82 Honda Civic, $2.77 on closeout, made in Italy

Standard motor SLS128, for ‘82 Mazda RX7, $3.73 on closeout, made in Japan.

Both switches feel very sturdy and heavy duty compared to the Chevy/GMC switches.

I’ll use whatever one fits best.


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