Damn Brake Light Switch,

artz1731

True Classic
almost got rear ended today. I am replacing the brake light switch for the third time in two years. What's up with these switches? Are they just made too cheaply these days? Not much to them, can't figure out why they keep failing.
 
You need to examine them and see what is failing about them. Contacts, spring, plunger?

We fixed Rod's switch at OR '16, I don't know how old it was.

The spring had broken. We used a ballpoint pen spring with a piece of the broken spring screwed onto it for diameter. Worked great and might outlast the car now.
 
The current switch

Can't be taken apart without breaking it. So since it was useless I broke it apart to inspect. Like the last one I replaced, the contacts on one side are all black. I'm not sure what would cause this or how to prevent it.
Oh well I just ordered another one hopefully it last more than 6 months.
 
Brake not returning all the way to the top due to weak spring or dragging pivot point?

That would tend to cause the brake light switch to remain slightly in contact and arc.

Let the pedal return slowly on its own until it stops, see if it happens to stop as soon as it touches the switch plunger.
 
So your thinking the pedal doesn't push the plunger in all the way on the switch.
I don't believe that to be the case but I'll have to check it out when I get the new switch.
 
If you are finding melted/black plastic that makes Me think you have a short (how much current do you draw when the break lights are turned on)... Maybe a bare were some where that only touches every so often.
 
No melted plastic.
Plenty of return on the pedal, return spring not an issue.
The one contact has a slight black buildup on it which I believe leads to poor contact on that side.
One of the switches that I pulled last year I was able to take apart and clean the contacts, so I put that one back in the car for now and it is working fine.
 
Sounds like something isn't right. The switches shouldn't be passing much current through them. With toasty contacts you would think it wasn't closing the circuit all the way but not on a few switches. If I were you, I would put an amp meter between the switch connector and verify the current draw. With 30 year old wiring it wouldn't be a surprise to find a slight short pushing the current draw into the 10-15 amp range. Also, double check the bulbs and be sure they are correct. Believe the brake light bulbs are 1157 or 2057. Sure someone else remembers exactly.
 
I think those lights draw more than you'd think, my cluster lights go dim and my volt meter flickers every time I push the brakes which is a little silly for two little brake lights, I have heard others say the same. Poor switch design or some corrosion causing too much resistance maybe?
 
Shouldn't be 10 amps. Just 2 bulbs for the brakes unless I'm confused. They are rated at 2.2 amps each so 4.4 amps. Maybe 5 ish with old but not bad wiring.
 
1073 bulbs are listed in the shop manual 23W 1.8 amps. The ones on the car are K 15326 25W unknown amps as I can't seem to find specs on this bulb.
I'll need to stop at Autozone tonight and pick up the correct ones.
 
It shouldn't be 10Amps though..

they're 21 Watt lamps x2, 42 Watts * 14V nominal = 3A - a little higher at 12V.
 
Why not just switch to LED's and be done with it. Current draw will no longer be a factor.
Mine is very happy with a full LED conversion. Cheers,


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It shouldn't be 10Amps though..

they're 21 Watt lamps x2, 42 Watts * 14V nominal = 3A - a little higher at 12V.

A little lower at 12V; they won't be at the rated power at the lower voltage. The 1073 bulb is rated 23W at 12.8V (and thus 1.8 A). At 12V it will only be 20.2W and 1.7A.

As Steven L pointed out, the bulbs will draw several times their nominal current at startup when the filaments are cold.
 
1073 bulbs are listed in the shop manual 23W 1.8 amps. The ones on the car are K 15326 25W unknown amps as I can't seem to find specs on this bulb.
I'll need to stop at Autozone tonight and pick up the correct ones.

If you are replacing the bulbs, I would suggest (as Crusader did) converting to LED, as these draw much less current and don't have the large current spike on startup. If you do change to LED, make sure to get red LEDs. White LEDs behind red lenses look awful, and a lot of light is being wasted.
 
I am all for LED's and noticed a marked difference when I changed over but it sounds like there are other issues with the wiring. You are getting some kind of short that is putting more amps through the switch than it is rated for. The first place to look is for wiring that is being moved around when the brake peddle is depressed and touching a bare positive wire to ground. I have never had any problems with those switches. I have on one occasion used an old Fiat brake switch from my junk drawer to replace a broken one on a friends non Italian car.
 
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