I'm putting in a reman starter and thought I'd look for some advice. This page has a good write-up:

http://www.gbcnet.com/mercedes/docs/OM603%20Starter%20Motor%20Removal%20and%20Installation.pdf

At the end he talks about the relay:

As a bonus, I added a relay to the wire coming from the ignition switch (the small one). Bosch makes a kit for this and my word of advice is to make sure there is a 15 amp fuse between the battery and the relay. The way it works is that rather than have the current to actuate the solenoid (and therefore the starter) go through the ignition switch and Outer Mongolia, the relay acts like a remote switch, giving the current far less distance to travel, and much less resistance. This significantly reduces the chance of the starter motor unexpectedly not starting, as well as providing more robust starts. The only thing the wiring from the ignition switch has to do is to switch on the relay.

Also speaks of a Bosch relay kit. Anybody done this or know if it's a good idea or not? I was under the impression that relays for this were standard.

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