Ken, here are the reading from my 99 ML430. Only ME and Transmission available. (this is ME 2.0 system)

OS2 Voltage before TWC Left 84 - 714
OS2 Voltage before TWC Right 90 - 734
Lambda Control before TWC Right -1 -- +1
Lambda Control before TWC Left -1 -- +1
OS2 Heater before TWC Right On
OS2 Heater before TWC Right Voltage 0.13
OS2 Heater before TWC Left On
OS2 Heater before TWC Left Voltage 0.25
OS2 Voltage after TWC Left 499
OS2 Voltage after TWC Right 489
Lambda after TWC Left (ms) 20
Lambda after TWC Right (ms) 60
Ignition duration Left (ms) 2.97
Ignition duration Right (ms) 3.03
Air Mass (kg/h) 16
HFM voltage 1.38
Manifold absolute pressure MAP mbar 323
Manifold absolute pressure MAP voltage 1.31
S/A CTP (Idle) Left (ms) -0.19
S/A CTP (Idle) Right (ms) -0.14
S/A partial load Left 1.04
S/A partial load Right 1.03
S/A delay time Left (ms) 0
S/A delay time Right (ms) 0
Load correction Factor 0.89
After start enrichment off
Engine speed RPM 650
Nominal engine speed 649
Engine start temperature C 81
Engine Coolant temp 85
Engine Coolant temp Voltage 0.78
Engine Oil temp 82
Engine Oil Level OK
Intake Air temp 29
Intake Air voltage 2.23
A/C compressor off
Battery voltage 13.6
Throttle valve angle 2.8
Learn Value Throttle Valve Stop (%) 11.56
CTP recognition on
WOT recognition off
CTP adjustment value (deg) 2.49
CTP Long term adaptation value (deg) 2.4
Throttle valve stop learned yes
Actual Signal 1 (V) 4.33
Actual Signal 2 (V) 0.64
Pedal Value sensor 1 0.30
Pedal Value sensor 2 0.15
Air Pump off
Camshaft Hall Effect Sensor 55 - AA
Fuel Tank Level OK
Purging off
Purg Valve duty cycle (%) 0
Tank Pressure difference (mbar) 0
Tank Pressure difference (volt) 2.99
Misfire Cylinder 1 (1/SxS) 0.00
Misfire Cylinder 2 (1/SxS) 0
Misfire Cylinder 3 (1/SxS) 0
Misfire Cylinder 4 (1/SxS) 0
Misfire Cylinder 5 (1/SxS) 0
Misfire Cylinder 6 (1/SxS) 0
Misfire Cylinder 7 (1/SxS) 0
Misfire Cylinder 8 (1/SxS) 0
Misfire fault counter Cyl 1 0
Misfire fault counter Cyl 2 0
Misfire fault counter Cyl 3 0
Misfire fault counter Cyl 4 0
Misfire fault counter Cyl 5 0
Misfire fault counter Cyl 6 0
Misfire fault counter Cyl 7 0
Misfire fault counter Cyl 8 0
Misfire recognition shut-off threshold (1/SxS) 1.92
Knock control approval off
Knock Ignition angle Cyl 1 0
Knock Ignition angle Cyl 2 0
Knock Ignition angle Cyl 3 0
Knock Ignition angle Cyl 4 0
Knock Ignition angle Cyl 5 0
Knock Ignition angle Cyl 6 0
Knock Ignition angle Cyl 7 0
Knock Ignition angle Cyl 8 0
Knock Sensor Left Voltage 0
Knock Sensor Right Voltage 0
Ignition angle 12
Vehicle speed front axle (mph) 0
Vehicle speed rear axle (mph) 0
Cruise Control shut-off function yes
Cruise Control shut-off safety yes
Cruise control off
Stop lamp switch off
DAS and ECU compatible yes
ECU identified yes
ECM locked yes
Number of starts with non-locked ECM 0
Start Autorization yes
Transmission overload protection off
Transmission shift delay off
Adapted ranges L1 off
Adapted ranges L2 off
Adapted ranges L3 off
Safety contact off
Selector lever position P,N
Hold gear off
Decel shut off off
Safety fuel shut-off off
Torque (NM) 66
Engine load (%) 17
Exhaust temperature TWC model © 308
TWC heating at idle off

It can do the following tests:
Air pump, Injectors 1 -- 8, Throttle valve, Fuel Pump, Purging, Charcoal Canister shut-off valve, EGR, Fuel trim, Intake Manifold switch-over valve.

Transmission has a lot too, but I don't have time to check it now, just look through it. You can do some activation as well.
Cartrige from SnapOn comes with all you need - 38 pin cable, OBD2 cable and 3 keys. Also cable for older MB with banana plug. It comes with the manual, but it is a general description of the parameters, so it is hard to tell what's available for your car.
If you decided to get it, order optional flat ribbon 25 pin cable p/n MT2500302 so you can close the hood and door and drive with it pluged. It comes with reqular cable and it is too big to close the door on it.
Reg. Mike