Brake Light Switch? How do I tell if it is faulty?

[luke_a]

I'm getting sick of my car constantly having a flat battery.

When we had the first lot of snow, and low temperatures, I noticed my rear brake lights were on - even though the car was parked and locked up and hadn't been driven that day. So I opened it up, stomped on the brake pedal, and the light went out. It started fine the next day.

Everything was fine, till we got the second lot of snow. Someone who lives in my block of flats told me I had left my lights on. So I stomped on the brake pedal, lights went out. Though on Monday morning, the car wouldn't start, so I couldn't get to work. Great.

So I charged the battery up all day, bought a new battery as a spare in case the car strands me again, and everything was fine for a week.

Yesterday I go to get something out of the car, and the fob doesn't work. Great. Flat battery again.

I've read that this may be caused by a faulty brake light switch, how do I diagnose if that is my problem, or if something else is causing it? Preferably I don't want to have to go back and forth to the dealer constantly, as odd electrical faults are often simple fixes but expensive to diagnose.

For now I'm either going to have to remove the "clutch pedal switch, brake pedal switch" fuse (F39/F22), or disconnect the battery, each time I get out of the car. Just to be sure the car doesn't flatten the battery. This will get tiresome quickly, so I hope someone is able to shed any light on this problem.

[luke_a]

Odd. Removing the Brake pedal switch fuse does not prevent it from turning on the brake lights. In the end I had to remove (13?) from the fuse box next to the steering wheel. This prevents the brake light turning on with the ignition off, but with the ignition on it turns all the lights on. God this is going to be a ballache to keep putting the fuse in and out.

[silver1011]

2x 21W bulbs and a strip of LED's will flatten a 2005 battery overnight so it is almost certain that this is the cause of your repeated flat battery's.

Once a battery is drained (especially completely flat by a constant draw from the bulbs) it is unlikely to hold a full charge again, so even though you have recharged it it will now flatten quicker.

The simple solution here is to find a local 'automotive electrical specialist' open between Christmas and New Year and get it booked in ASAP.

I've heard access to the brake light switch on the Octavia is a real pain, not something I'd want to tackle myself in a damp footwell kneeling on snow with cold fingers.

I'd would resist the urge to keep pulling fuses, quite often fuses are multipurpose so breaking a circuit will likely disable another essential function too.

Until then flat batteries, knocks on the door from neighbours and being late for work is something you'll have to get used to.