95'1.3 Polo 6n drivers side brake light comes on at random, flattening the battery!

Any ideas as to what could cause this? Don't think it would be the brake switch as both lights would come on?

A light tap to the steering column sometimes cures this.

Many thanks.

Are you sure it's the brake light ? as it's only on one side that rules out the switch, but if it's the side light then that would tie in with your "tap" of the steering column and it's the " parking light" coming on via the indicator stalk

Yep it's definitely the brake light! It's the 21w bulb right at the top and not the 5w one beneath it

When it comes ON check the headlight to see if the sidelight is on

Followed the Polo this morning. It is definitely the brake light and is a complete separate light. When braking both brake lights illuminate but when the pedal is released the drivers side brake light stays on. Ordering a new brake light switch anyway as they're not expensive, if that doesn't sort it I'll have to dig deeper!

Does it only occur if the side lights are on? if so it's probably a partial short on the bulb holder (not an uncommon fault)

The dealers wiring diagrams show there is a single wire from the fusebox that goes to the back of the car, where it's spliced to then feed both light units, so if both lights come on when the pedal is pressed it can't be the switch :)

Nope, the light can come on at random! It can be parked with no lights illuminated, then an hour or two later the brake light will be on!

And ah, right, that makes sense. I'll have a proper look tonight for any corrosion or broken contacts just to make sure.
Cheers :)

Do both brake light give equal brightness?

If not, there may be a poor earth connection - but that would still need to have a supply from the brake light switch to make it light - make sure that the switch hasn't 'bridged out' (by a 'floating' strand of wire for example).

Regards