In my 123, if you just fiddle around with the dimmer (go from hight to low with the knob) and eventually the lights come on. Do your dummy lights work? I think they're on the same circuit. The cruise in these cars tend to never work, so it might just be a lost cause. I just tore out all the cruise stuff on mine.

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1983 240D 3.0T 4-speed manual, now sold

1989 Subaru GL Wagon 5-speed Touring Edition