Dipped Headlight Failure

[320CAB]

Can anyone help. The sidelights and main beam work fine on my 1991 500SL but the dipped lights don't. There is power to both the left side and right side fuses but when either of the bulbs is in the bulb holder the power drops to less than 0.3 volts. The earths seem fine and are shared with the main beam and sidelights. In summary when either side or both sides have a bulb in then the voltage drops away. Any ideas on what else I can check or alternatively does anyone have a wiring diagram ?

 

[jaymanek]

Have you checked that there isnt a problem with the switch?? Its very odd that only the dipped isnt working...

 

[Brian WH]

Sounds like a dodgy bulb holder, it is shorting out the bulb to earth/itself and causing the voltage drop.

 

[Ralph]

If it was a short the fuse would blow. Somewhere in the positive (non earth) circuit there is a bad connection. Across this connection when switched on, you will be able to measure ~12volts and possibly HEAT. Could be the switch as suggested above. It needs attention, do not leave the dipped beams switched on as serious heat can develop.

As the earth circuit is OK, by deduction, it is not before the switch otherwise the main beams wouldn't work. Assuming each dipped is separately fused, again it isn't after the fuse box. 95% certain the fault lies with the switch, fuse box or wiring / connectors between. If I had to guess one, it would be the switch.

 

[guydewdney]

http://www.autolib.diakom.ru:8001/CAR/Mercedes-Benz/1996/S420/SYSTEM WIRING DIAGRAMS/5985.pdf

ok its the wrong car - but it might help...

 

[320CAB]

Thanks for the help, still not sorted but a few more things to check. I'm out of country for next few weeks but I'll post the solution once I find it !!!!
Cheers

 

[320CAB]

Problem sorted

The problem was the steering column multi switch. Thanks for your interest and help.

 

[guydewdney]

what was it?

edit - colour blind and couldnt see yellow on white...

 

[Steve_Perry]

what was it?

The problem was the steering column multi switch...

S.