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Hi All, I am working on my 2003 E500 the battery would intermittently drain so I had the Alternator replace and also did a fuel pump replace (eventually found out that after the pump replace I didn't have to). This is what's weird.... The last time a ran the car it ran until the Battery drain and stopped, I ordered a used Alternator on ebay and had it replace and since replacing the alternator the car has never started. I have tried so much that I have worn out the brushes on the starter just replace that today, I have fully charged the battery and I'm planning on running the car with the alternator disconnected does anyone have any other things I can try. DTC codes is not showing anything of real interest, one guy saw some DTC airbag codes and is convincing me that it's the air bag but sounds a little hard to believe.
On these cars the synchronization between immo unit and key - rolling code - easily gets lost with battery problems. Make sure the key is recognized or try another valid key.
An expert is someone who knows each time more on each time less, until he finally knows absolutely everything about absolutely nothing.
You should have pretty much the same voltage at the alt as you do at the battery. This makes me think there is a draw since voltage drop only occurs when there is current flow. Were these measurements taken with the key on? That's a large drop, no matter what, so I'd redo the connection there.
I'd charge the battery and do what juergen said to do. Also a parasitic draw test to see if there is excessive current draining the battery. If the battery was still connected during the alternator replacement, I'd check the fuses too, or if there is any chance that it was reverse jumped by accident.
