Electrical fault on R129 300SL

[R129-300-24]

I have a 1991 SL 300-24 R129-61 with an electrical problem.
The symptom is that, intermittently, (80% of the time), when the indicators are used (left or right), oil warning light flickers on, the fuel gauge drops back to zero and back up to its original position AND the cruise control has an instantaneous surge which borders on "interesting!". When stationary, with ignition on but engine off, the symptom is the same (expect the cruise surge, of course!). An independent auto electricion pulled out the intrument pod looking for a dry joint but found no faults and no fix. I've now been advised it could be the relay, part no 129 820 10 26, but I'm wary of spending loads of dosh to find it's not the problem. Has anyone across this sort of problem before or any idea of cause?

 

[EDZ649]

It does sound like a short somewhere but you never know with these things. Best to get the codes read before you go any further....

 

[R129-300-24]

It does sound like a short somewhere but you never know with these things. Best to get the codes read before you go any further....

Thanks for quick reply. Excuse my ignorance, but what are "codes" how do I get them read?

 

[EDZ649]

You will need to take the car to an MB specialist who can read the fault codes stored in the car's memory. Changing parts without proper diagnosis is like looking for a needle in a hay stack when you have an electrical fault.

Probably the nearest to you is SS Motors in Weybridge, they have been recommended on here a few times and they are quite familiar with SL's IIRC.

If you fancy a bit of a run you could always pop down to PCS in Horndean.

 

[stats007]

Sounds like the combination or OVP relay.

 

[R129-300-24]

Sounds like the combination or OVP relay.

Thanks to all for responses. Again my igorance, what, stats007, is an OVP?