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[Solved] Where in the brake system can cause battery drain?


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1999 Honda Accord

My battery died. It was old. Jumped it a few times. Starter good. Alternator good. Had this happen a couple times over the past 20+ years. Thought it was just a battery eventually going bad. So I replaced it with a battery from Costco.

But then after replacing it, driving around a bit, I noticed my brake lights staying on when parked and the car off. With this information, my guess is that there is something in the brake system that is being left “on”. Thus causing parasitic drain. But what could that be?

I had to leave the car since I am traveling for thanksgiving. I made sure to remove the negative battery terminal, as to not drain while I am gone. Hoping to delve in deeper when I get back next week. In the meanwhile, looking for possible solutions to this problem. Thank you for your insights. 


3 Answers
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UPDATE: Solved!!!

The brake pedal stop pad broke, and constantly left the brake in the on position. Tool more time to drive back and forth to AutoZone than to install the actual part.

Thanks for pointing me in the right direction!

Excellent! @kaizen


Faulty brake light switch on the pedal?  Missing ground connection?

The circuit to the switch is always hot, which is why stepping on the brake even when the engine isn't running turns on the brake lights.

That’s interesting. Thank you.


I noticed my brake lights staying on

probably the brake switch, it's cheap.

If the issue persists then it requires a more in-depth diagnosis - like this: