Hi, im having an issue with my brake lights and rear lights in general, when i turn my headlights on my brake lights come on apart from my brake light bar at the top of the boot lid, when i turn my headlights off they all go off and the brake lights work normally.

as far as im aware it would be a faulty brake switch, would this correct? or would i need to look else where?

If it was the brake switch, the high level light would be on as well.  This is either a short in one of the clusters, or potentially the BCM.

4 hours ago, kingtetley said:

as far as im aware it would be a faulty brake switch,

100% it is NOT the brake light switch.

A common cause of such behaviour is a faulty 'Tail/Stop' bulb. If one of the twin filaments inside the bulb breaks and touches the other filament then you can get the fault you have. The centre brake light is usually on a separate circuit, supplied from the GEM/BCM and so it's not affected.

Simple and quick solution is to replace both the brake light bulbs.

If the problem continues after replacing both brake light bulbs, then the fault will be with the GEM/BCM, quite possibly water ingress.

For anyone still experiencing this, I had this same issue on my 2008 Smax.

In my case it was also was creating a 'stop lamp bulb fault' on the dash.

The connectors on the bulb itself are slightly offset.

The assembly for the bulb allows the bulb to be inserted incorrectly and connectors are reversed. The circuit then mistakenly lights the filament responsible for the brighter light (when brake pressed), in place of the standard running tail lights.

Simply take out the bulb, rotate it 180 degrees and reinsert. It should be a snugger fit that it was before. Hope that helps!

Note - also replacing the bulbs would have had a 50/50 chance of fixing it, if you managed to get the correct orientation while replacing :-)