Specifications

21
Chapter 5 Data Parameters
When DATA is selected, the Scanner displays all of the operating parameters available from the
electronic control unit (ECU) of the vehicle. The ECU provides two basic kinds of parameters:
digital (or discrete) and analog:
• Digital (discrete) parameters are those that can be in only one of two states, such as on or
off, open or closed, high or low, rich or lean, and yes or no. Switches, relays, and solenoids
are examples of devices that provide discrete parameters on the data list.
• Analog parameters are displayed as a measured value in the appropriate units. Voltage,
pressure, temperature, time, and speed parameters are examples of analog values. The
Scanner displays them as numbers that vary through a range of values in units, such as
pounds per square inch (psi), kilopascal (kPa), degrees Celsius (°C), degrees Fahrenheit
(°F), kilometers per hour (KPH), or miles per hour (MPH).
The Scanner displays some data parameters in numbers that range from 0 to 100, 0 to 255, or 0
to 1800. These ranges are used because in each case, it is the maximum number range that the
ECU transmits for a given parameter. However, many parameter readings never reach the
highest possible number. For example, you never see a vehicle speed reading of 255 MPH.
For Mercedes-Benz vehicles, the maximum range of a parameter often varies by year, model,
and engine. On these applications, the word “variable” appears in the range heading. However,
typical sampled values observed under actual test conditions are in the parameter description
when available.
Parameters may also be identified as input signals or output commands.
• Input or feedback parameters are signals from various sensors and switches to the ECU.
They may be displayed as analog or discrete values, depending upon the input device.
• Output parameters are commands that the ECU transmits to various actuators, such as
solenoids and fuel injectors. They are displayed as discrete (ON/OFF parameters, analog
values or as a pulse-width modulated (PWM) signal.
In the following section, parameters are presented as they appear on the Scanner screen. Most
parameter descriptions are in alphabetical order, but there are exceptions. Often, the same
parameter goes by a similar, but different, name when used on more than one model, engine, or
control system. In these instances, all of the applicable parameter names, as displayed on the
Scanner, are listed in alphabetical order before the description.
To find the description of a parameter, locate it in the alphabetical index, then go to the indicated
page. Parameters are listed in the index as they appear on the Scanner screen.
The data parameter descriptions in this manual were created from a combination of sources. For
most parameters, some basic information was provided by Mercedes-Benz, then expanded
through research and field-testing. Parameter definitions and ranges may expand as more test
results become available. For some parameters, no information is currently available.
The Scanner may display names for some data parameters that differ from names displayed by
the Mercedes-Benz factory tool and other scan tools.