Sorry to "necro" this thread, but I wanted to detail my final solution to this whole thing so that others might benefit from it.
1. Tighed was able to put on a new relay which fixed the relay issue, he rocks. The extra RCM from ebay that I had also would have worked.
2. The secondary air pump did indeed burn out. Even though I had kept it disconnected, it seems that the damage was done and only after a few hits with a hand would it even make a sound. The dealership quoted me 1300 bucks for one.... But on ebay I soon realized our pump is synonymous with many other Mercedes pumps, at about 250-400 bucks used.
3. Instead of buying one of these, I contacted an ebay user named
rostykf who remanufactures many of the Mercedes pumps which are similar to ours (
His Ebay Post He said that I could ship mine to him and he would see if he could fix it for only 109 bucks + shipping (he said it was free if it wouldn't work). Very quickly after receiving it, he detailed what was wrong and offered a lot of great information about the cause (the relay), he assured me he could remanufacture it and sent another one my way to cut down on the wait time. After installation, the newly remanufactured pump purred like an oem kitten and the CEL is now gone. You can tell he does quality work, the pump looked practically new. It's hard to say how long this pump will last, but for 109 dollars it's an excellent alternative to buying an old pump for much more.
I hope this helps someone!
Kolme