Greetings,
Just got my first MB rolling - a 1981 300D which has had a turbo engine / transmission installed. Love it so far, an absolute pleasure to drive, but I'm having weird electrical problems.
Any electrical wizards out there familiar with these older gems?
1) The high beam relay is energized (clicks and the high beams come on) at all times when the ignition switch is in the running position. Dashboard headlight switch and steering column dimmer switch have no effect on this. Steering column dimmer switch will turn on low beams, but the high beams also stay on as long as the ignition switch is in the run position.2) With the ignition switch off, the dashboard headlight switch works as expected, and the steering column dimmer switch properly toggles between high beam and low beam.
3) The steering column dimmer switch "flash" position has no effect ever.4) (I love this one!) The climate control will activate with the ignition switch in the off position, the dashboard light switch turned full on to the headlight position, and the steering column switch set to the high beam position. I just discovered this the other night when it got a little cool here (sorry northern buddies, but those central Florida nights get really brutal - sometimes even below 50 ;-)
To date, I've removed the dashboard headlight switch and verified the color-coding of the wires to the proper terminals (at least as far as my Haynes schematics show, they're correct). I've removed the (non-functioning) aftermarket radio and the climate control panel and looked behind them for evidence of goofy wiring. I've tried to find the high-beam relay behind the climate control panel, because that's where I hear it clicking, but it may be buried a little deeper under the dash.
I have also taken out the steering column dimmer switch, and slipped business card pieces between the switch contacts to ensure they were separate - I have also swapped this switch with a friends W123 - no change.
I'm suspecting some creative wiring at some point in my car's history, but I'm not sure where it's most likely to have occurred - On the other hand, I've also had poor ground connections cause some odd symptoms in other vehicles.
Hope this rings a bell for someone out there. I know it's a little weird - maybe I should submit it to the Tappet Brothers for their weekly quiz.
Thanks much for your time and head-scratching,
Conrad