speed relay repair ???

[BHap]

I have a 1970 280SL with the ignition retard / advance setup...  It appears that my speed relay is faulty.  Is this part available new / used?  Can this be repaired?  The box is numbered 000 545 08 32.  The unit receives rpm on pin 4, but does not send 12v to vacuum switch above 2400 rpm (or ever)... jumping pins 1 and 2 energizes vacuum switch....  any help is greatly appreciated...

[jeffc280sl]

Hi Bob,

You seem to have isolated the problem.  I purchased 2 used speed relays and found they were not functional. I suspect many others are broken and people are just unaware of it. I don't know of anyone that repairs them.  

I have replaced mine with a digital rpm switch and it works fine.  If you are going to go this way let me know or search prior posts of mine that describe how I fixed  the problem.

Jeff C.
1970 280SL 4-speed

[BHap]

ok - I'll answer my own question.... Beckmann Technologies in Durham, NC repairs rpm switches and many other relays etc for Mercedes Benz cars...  Many Thanks to Jeff C for his very patient explanations of the ignition timing retard/advance system and his use of the MSD digital rpm switch...  I would have gone that way, but the MSD switch was back-ordered two weeks and Beckmann promised me a 1 day turnaround....  I should have my rpm switch back by Tuesday...  In the meantime, I installed a toggle switch that retards the ignition at idle and gets turned on to assist timing advance above 2400 rpms....

[mdsalemi]

BTW all the relay cans in most 113's are available...I replaced all of mine a year or two ago, and got most of them from a local Bosch dealer.  All you need is that relay number.





Michael Salemi
1969 280SL
Signal Red w/Black Leather
Restored

[tuultyme]

BHap
did you get your speed relay back from Beckmann and installed?  Let us know if it is now functioning properly.  I sent my speed relay to Beckmann this week for repairing.

Bruce; 268Blaugrun(green) 1970 280SL; IL