I read in an old thread that it was possible to make a diagnostics unit from an interior light.
The fault codes are meant to be read from the amount of times the interior light flashes.

I tried to make one and it was all connected to the right pins in the diagnostics terminal but it failed to work, (I tested it from the 12v source in the terminal and the light worked fine). The description on how to make it was relatively simple but I must've been doing something wrong, the light just wouldn't flash? I had a wire running from the 12v source to the pos on the interior light, and the neg of the light running into the engine diagnostics pin as the thread described. When that didn't work I tried connecting the pos on the light to the engine diagnostics pin and the neg if the light to earth which also didn't work.

Does anyone know what the configuration is meant to be? I can't find anything on it.

Cheers.

documents.php?d=52

Hey mate that's the document I followed, wired it up like it said and it failed to work.

Would anyone know why this would happen?

I had the 2 pins bridged (correct pins of course), had a wire from the STO pin to the light then the other wire from the light to the neg battery terminal, followed the ignition steps properly and it just never flashed.