Head Lights Will Not Turn Off

Hi,
I have an issue wherby my headlights will not turn on on my SL 300 1986.
So I have to disconnect the battery to actually get the headlights off.
Had the car for 3 years, and it has never happned before.
Is it the light relay?
Many Thanks for any feedback
Rune (Norway)

Hello Rune,

I think that the lightswitch is the problem. Are you able to switch from the headlight to the parkinglight position?
You you have a daylight circuit?

If you need a wiring diagram for the 300 SL, send a private message with you E-Mail address to me, and I will send the wiring diagram to you.

Hi Rune,

well is it just both low beam headlights or also backlights and parking lights?

Power comes from lights switch via combination switch on steering wheel (to flip low beam and high beam) , fuses and a lamp control module to headlights. Lamp control module warns if a light bulb has wrong resistance.

Cable on light switch for head lights normal beam is 56b L (ye-bl) and 56b R. (ye-rd) from fuses 19 and 20 to lamp control module. Marcel can help with a German wiring diagram. So you either have cable contacts ot a shortcut in the two switches or in lamp control module. How to temporarily disconnect? Remove fuses 19 and 20.

Thanks Marcel for your answer!

It does not change when I put it in park light position, however when I put the fog lights on, it changes to the park light on headlight as it engages the fog lights.

Also another observation, I disconnected the battery and connected it back, but the lights are still on.

I removed the fuses, 19 and 20, and it was still the light in my panel showing the red battery light. So the batt light is still flashing red after I have fully turn the car off and taken out the key and removed the fuses?

I sent you a message with my email.
I can add that my diamant here is very little used, it has 76K on it and in mint condition, so first time I have any issue with anything.

Rune

Hi Rune,

check your E-Mail Box.
I wish you luck in troubleshooting this problem.

Dr D Jet,
Thanks very much for your answer, this support is great.
It is both backlights and the low beam headlights.
When I put on parking or put the switch to `0`, it lights remain the same. Only when I engage the fog lights, it changes.

Fuses, even after taking the fuses out, I will see the red batt lamp light on in my dashboard.

So cable contacts or short cuts in switches. Is this something a Autowerkstatt can help me with or do it require some specialists you think?

Hi Rune,

any car elextrician should be able to find that problem. It looks like there is some strange cable contact somewhere. To search that can be time consuming. I would start to pull all fuses until head light turns off. The circuit where the pulled fuse lets the lights turn off would be my candidate to search for the shortcut.

Dr D Jet, & Marcel,
Many thanks for your support and guidance during this search.
The car is now repaired.

For the benefit of others, this was the cause of the faulty lights:
The light relee was changed and the headlight issue went away. The workshop used the diagram provided by you during the search.

Subsequent another issue happened and that was the batt light was glowing red while driving. This intitially was thought to also be a part of the headlight issue and some kind of wiring issue.
However this was found to be that the dynamo giving it 19 V, not to the battery, but to the indikator lamp in the dashboard.
Dynamo was changed and it is now all working.

Thanks again this Forum for guidance, much appreciated.

Rune