I have a 1992 MB 300sl and the left turn light comes on automatically front and rear lights burn solid...

Generally speaking, symptoms of a bad or failing turn signal bulb are usually the culprit...in your case, either it's the front left or rear bulb. Varies for different vehicle makes...common signs include:

1. turn signal light staying on solid
2. or blinking very fast
3. or either sides of the bulbs stop blinking altogether.

To test this, make sure you reconnect everything you disconnected.
Turn the left signal light on; go to the front of the vehicle, is the turn signal bulb illuminated? If it lights up, even though it is not blinking obviously the bulb is okay. If it doesn't, replace it- problem solved. You'll do the same procedure for the rear turn signal Is that lit up? If not replace the bulb and the problem is solved.
Another common failure is when the turn signal blinks really fast, same procedure as mentioned above.
If both bulbs for the left side and right side illuminate but don't blink, the problem is in the steering column turn signal switch.
If the left or right side blinkers don't work properly at all...then check the integrated hazard warning/turn signal flasher relay- that may be defective; again, that's usually the case if both sides of the signal light don't work.
If you are blowing any fuses related to the flasher system, you have an electrical overload in the turn signal circuitry.

It seems to be a ground defect on right side. Do you have the same bulb's number . What about the front flasher. remove right rear lamp assembly remove connector measure voltage between ground and current .reconnect it measure voltage at bulb socket. you should find your problems
hope it helps

Hi

Did you check the fuses for the turn lights? Do the
parking lights work? If the parking lights work then you probably have a
problem either in the switch or in turn signal module thing.
The burned out bulb is what might be causing it not to blink... if one bulb is burned out you gotta replace it, make no difference if front or back,the left blinker will not work if the left front or rear bulb is bad.
same with the right side. if the front right or rear right turn signal
light is burned out it will not work.....get replacing the bulbs.Hope this solves your problem.Please rate me if my solution helped you.

Regards,
bonefirediv.

remove rear left lens and install new turn signal bulb.

Have you checked the fuse under the drivers side dash?Manual should give you an image and should be label'd

I’m happy to help further over the phone at https://www.6ya.com/expert/zelio_00a80ed57645ccbf

I just had that problem with my jeep cherokee and either your bulb has burned out or it is burning out. Time to replace it. Turn the signal light lever on the side that's flashing fast, get out of the vehicle and look at the front and back signal lights and replace the one that isn't blinking...hope this helps.

any increase in bink speed is direcly related to a bulb being burt out.

Replace the bulb that stays on and doesn't blink, if that doesn't solve the problem, let me know.

Blinker too fast, the same side blinker light bulb on the front (or back) is burned. Check the fuses for the rear lights. You might have a light bulb filament stuck.

You may have some corrosion in the socket where you plug in the bulb. This would cause the lights to not blink. Put the turn signal on, and check the lights, front and back. Are then on, and not blinking, or are they not on at all? If the bulbs are good, and they aren't on, it's the bulb socket problem. Get fine sandpaper, fold it around a pencil eraser, sand off any gunk or corrosion inside the socket. It could also be a faulty ground wire, check for a loose wire at the light assembly. front and back.countrycurt0