hi my 2.5tdi had same problem brake light switch if you push footbrake down with one hand place other hand at top of footbrake you will feel plunger for switch pull it up release pedal check brake lights are working you may need to do this a few times
this allways works for me a new switch about £8-00 from vw peteT:
I've found my orange glow plug light flashes it i've got a bulb blown somewhere. First time was as suggested a brake light. Second time was one of the head lights. Not sure if this is the case for everyone, but worth checking all the lightbulbs. I also had it with a number plate lightbulb. Hadn't had the van long when this first happened and made me worry it was something drastic, but this forum really helped with sorting it out.