83 Tintop brake lights

Hi guys, I don't post often on here but I am struggling to get the brake lights wired up. I have got to of the pressure switch set up in cleaning the bay up, I am left with two wires out of the fuse box - red/black and red/yellow. If I join the two together only the drivers side brake light comes on? Can any one help with a wiring diagram or tell me what I need to do with the two wire to use a manual switch system. Thanks in advance, Ollie

simple really, just need to fit a pedal box switch from mk2 golf and run the 2 wires from it. the later mk1 cab and scirocco used this kind of setup so you could switch the pedal box over from one of those. however iirc the bracket for the pedal is there you just need to drill a hole in it for the switch?

as for the wiring both rear lights run from the same wire to the fusebox, the fac 1 side works means this wire is fine. all it is the wire comes up from the rear to one of the lights, then the other side is piggybacked onto it. check the red/black wire to both clusters, check the earths and also check the light clusters themselves they can get corroded