Here are the relay pinouts:

1 = pink/red, +12V from fuse 7
2 = violet/white, +12V from key switch
3 = black, +12V to dash glow indicator
4 = brown, ground at W3 (beside glow relay)
5 = white, ground from preglow temp sensor B11/7 (beside thermostat)

Whaddaya know, Jeremy, B11/7 is the factory preglow temp sensor

Sixto
87 300D