starter-relay, etc. 85 380SL

When the key is turned to the start position nothing happens! All guages, lights including backup lights, radio, etc work properly. If I jump between the starter and starter solonoid the starter engages and engine runs fine. A friend who is a weekend mechanic said to replace the ignition switch, which was not an easy several hour job and did not solve the problem! Is there a relay somewhere that controls this? To make the car drivable I could put in a temporary switch between the solonoid and starter, but would rather fix it properly Any help would be greatly appreciated. Thanks.
Don

[laboyma53]

It sounds like you have a bad ground. I have been playing with my 82 starter and the....OH,,,,,,
The selenoid has two small screws (the wire goes to ground), use the bottom one. I had the same issue when installed the engine.
The "thick" wire should be accessible at the passenger side fender - next to the Antifreeze reservoir....check to see if you have 12volts or better there. If you have less than 10 volts - clean your connections and re-check. It is a start.