Help OVP relay

[sid300sl]

When I turn on the ignition on my 1992 300sl sometimes the instrument warning lights fail to come on and the outside temp just glows,I also can hear what sounds like a buzzing relay.Then after a few seconds the lights may come on or if I press the break pedal they come on straight away and sometimes they dont.The car will only start if the instrument lights are on but the starter will turn over the engine even when they are not on.Can anyone help could, it be the Over Voltage Protection relay :?:

 

[flagstaff]

just a hunch - but check your alternator! regulator unit in back (easily checkable, pull out and look for burning/pitting) may have shorted out due to wear, and be causing the symptoms you describe.

 

[Andy]

Hi

I would check the alternator regulator as flagstaff has mentioned & also the ignition switch.


Regards

Andy@ www.mercedesservicing.com

 

[sid300sl]

Hi
Thanks for your replies I have changed the ignigtion switch which I suspected in the first place and It seems to have cured the fault but as it has been intermittant only time will tell. I suspect that the contacts within the switch have become dirty and have been causing poor contact, only using the car at weekends may cause this type of fault (through lack of use.) I have fitted a S/H switch ( not the best option with this kind of fault) from a S class obtained from Dronsfields and although the steering lock switch and key assembly they supplied was not a direct fittment I was able to transfer the switch to my steering lock and key, and is now working fine: :

 

[Andy]

Hi

I think you will find the new switch from MB is about £13 or 14 from MB plus vat.


Regards

Andy@ mercedesservicing.com

 

[sid300sl]

HI
When I rang the local MB dealer in Grimsby they quoted in excess of £100 for a 1993 SL ignition switch (I had to buy the whole assembly) so I rang Dronsfield and thought that I had bought a new ignition switch for £75 untill it arrived complete with key and steering lock. I was able to remove the actual switch and fit it to my steering lock so I canot see why MB dont sell the switch as a seperate item.
It could be that the Grimsby parts dept got it wrong assuming that many SL drivers dont repair their own cars.
regards Sid