I went down this same research road and wasn't pleased with what I found. There are two types; Federal and California. As I understand, the California version does have a somewhat complete diagnostic system and the codes can be read by jumping something on the fuel pump relay. The Federal models, which is what I have, have very little diagnostics. There are a few trouble codes that can be read by measuring the duty cycle at the diagnostic connector. There are only a few subsystems that are indicated as a problem if present.
I expect that you will need the MB manuals to do any extensive troubleshooting on this car.
Please report what you find so that we can all learn from it.