Thanks for the suggestion guys. I took the relay apart and nothing jumps out as needing re soldering. The ignition seems to be reliable as in getting 12v to the relay reliably every time. However the solenoid does not always engage.

The relay does work about half the time. And when it sticks and I disconnect everything and reconnect it seems to work again. Decided I want a manual system rather than worrying abiut this relay or a used one from the junk yard. and so I ordered the manual kit from Mercedes source to try out. I always wanted a push button relay and having a pre assembled kit worked out well for my schedule.

I am glad I did pin point the cause. And luckily it is my winter car so I can afford the down time.

Thanks again for all the help

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198? 300D ???K - Future DD
1989 300TE 285K - traded in '12
1984 300SD 186K - Sold in 08
1978 300SD 330K - Died in 05