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Discussion Starter #1
1998 stock mustang

I have replaced my brake light switch twice in the last year and still same issue.

The female disconnect at the top terminal (red) is getting too hot. See pics below.

(I'm selling my car to a family member and would really like to fix this so the brake lights don't go out and possibly cause a wreck.)

Any suggestions?

thanks in advance
 

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get a dc clamp on there measure the current at the switch, and at the brake lights, the stock connector should not be melting.

you must have a bad connection or another load, or partial short to ground.

get rid of those stake ons...
 

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Discussion Starter #3
Does it matter if I measure voltage instead of current? And what do you mean by "stake ons"?

By the way I pulled off the bottom terminal (blue) yesterday and noticed the wires were corroded and copper wire strands were breaking off at the female disconnect. As before, I will cut away the wire and replace with a new disconnect, but I don't think this will solve the issue.

I'm almost ready to run a whole new set of wires with an inline fuse, but not sure how difficult of a job that will be. (I would need the electrical shematic)

Also yesterday I checked for VDC at the switch terminals to ground, but it was zero. Maybe I need to check from the positive terminal to the switch terminals in case that switch is connected to the negative side of the battery???

Thanks for your interest.
 

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Current is the only thing you are concerned with

Current is causing the heat NOT VOLTAGE

Most people dont have a dc clamp $$$$

But you need the right tools
 

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Discussion Starter #5
R=V/I

Ohm's Law, resistance is equal to voltage divided by the current. Without a voltage potential, current could not exist. But I will try to measure the current as well. Not sure how to use a clamp meter so should be a good learning experience.

thanks
 

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What?

are you measuring directly across a load?

What is the loads' resistance then?

How will you know if the current is higher or lower than is expected, ie if there are two or more loads?
 

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Discussion Starter #7
the truth is i dont know.

Talking to an electrician at work, he said it could be a bad connection. Another told me it is a local problem only occurring at that switch so may be best to change out and soder for a solid connection. So that's what i did, see pics.

Hope this solves it.
 

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you need to measure current.

I cannot overstate it,,,,,,,,you are just guessing if you don't know how the heat is being created.

Im a certified electrician, under 750volts...., your friend must have a DC clamp to borrow.
 

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Discussion Starter #9
Ya, i told the owner to keep a close eye on it. If the same issue occurs, I'll run a new line/wire with 25amp fuse /same as callout / directly from the positive terminal of the battery to the switch terminal. the other wire to the brake lights from the switch terminal i will leave alone because that's more work than im willing to do.

thanks for the advice, it's never in vain even if i do not completely understand it.
 

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Is this a shop?

you the owner or mechanic?
 

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Discussion Starter #11
I was the owner until yesterday. Just a DIY mechanic when I can. I sold it to a relative of mine, so they will inform me if the problem persists and I can help to try and fix. uncertified :^)
 
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