Bizman928

I am struggling with the wiring for my 3rd brake light on MY88.
I fitted the same 3rd Brake light onto my previous MY89 928 S4 using the correct wire in the existing loom which is the bottom black wire in the socket in the roof lining. I have wired up to the same wire in MY88 S4 and it doesn't operate the brake light???

Checking the wiring diagrams for both years it seems it should work OK so any idea's?

Thanks Steve

Bizman928

All sorted now witht he help of the 928.org guys. Paul Smith & Paul Lacey

Here's Paul Lacey's suggestion which I followed & worked a treat :-
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Take out the left rear light assembly, cut the outer sheath back a bit and look for Black/Red wire. This is power supply to brake light. Use a scotchlock connector or strip some sheathing back with a sharp knife and solder a new wire onto the Black/Red. Poke a little hole in the rubber grommet through which the lamp assembly securing post goes (the thing with the big alloy nut on the inside)

Tape up your Black/Red wiring / solder joint, feed new wire through the hole in the rubber grommet (not the mounting hole or it will get worn through) and replace the lamp assembly.

Run the new wire up the left side of the tailgate opening under the rubber weather seal to the top right corner. You will see there is a plastic guide up there through which the wiring passes from under the headlining to the tailgate. The idea is to route your new wire through that with the existing, it's fidly but I've done it a few times.

Remove the rear sun shades (four screws) then remove the top lining from the tailgate - the part with the interior light in it. It pops off but can be tricky, be patient and use a large flat blade screwdriver if required.

You now have access to your new wire and also the earth for the interior light (Black/White) and these are used for your third brake light. I use a strip of red LED type which has adhesive feet to stick on the very top of the rear screen.

This will not cause any type of bulb warning.

Hope it helps

Paul Lacey
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Works a treat!
Thanks guys

Steve