2006 MERCEDES-BENZ SPRINTER mirror controls

3.2.2 CAN BUS
The CAN bus (controller area network) is a data
bus system specifically design for inter module
communication on this vehicle. The CAN bus con-
sists of a special twisted two-core cable. Control
modules are connected to this9twisted pair9. The
CAN bus incorporates two terminating resistors.
One terminator is built into the Engine Control
Module (ECM) and the other is built into the Sentry
Key Remote Entry Module (SKREEM). Each resis-
tor has a value of 120 ohms. The resistor condition
can be confirmed by disconnecting the control mod-
ule and measuring the resistance value at the
appropriate control module pins. This measure-
ment should read 120 ohms. The two CAN circuits,
CAN C Bus (+) and CAN C Bus (-), are bridged by
these two terminating resistors when all control
modules are connected to the bus. These two resis-
tors are connected to the CAN bus network in
parallel. The measurement between the two
twisted CAN circuits, with both the ECM and
SKREEM connected, should measure a value of 60
ohms.
The CAN bus is bi-directional. This means that
each connected control module can send and receive
information. Transmission of data takes place re-
dundantly via both circuits. The data bus levels are
mirrored, meaning that if the binary level on one
circuit is 0, the other circuit transmits binary level
1 and vice versa. The two line concept is used for
two reasons: for fault identification and as a safety
concept.
If a voltage peak occurs on just one circuit, the
receivers can identify this as a fault and ignore the
voltage peak. If a short circuit or interruption
occurs on one of the two CAN circuits, a software-
hardware linked safety concept allows switching to
a single-line operation. The defective CAN circuit is
shut down. A specific data protocol controls how and
when the participants can send and receive.
NOTE: It is important to note the CAN Bus
circuits are used for inter-module
communication only, and is no way
connected to the K-Lines.
The following modules that use the CAN Bus on
this vehicle are:
²Automatic Temperature Control (ATC)
²Controller Antilock Brake (CAB)
²Engine Control Module (ECM)
²Instrument Cluster (IC)
²Sentry Key Remote Entry Module (SKREEM)
²Shifter Assembly (SA)
²Transmission Control Module (TCM)
3.3 HEATING & A/C SYSTEM
3.3.1 AUTOMATIC TEMPERATURE
CONTROL (ATC)
3.3.1.1 SYSTEM CONTROLS
The ATC Module:
²is fully addressable with the DRBIIIt.
IThe DRBIIItcommunicates with the ATC
Module through the Diagnostic Link Connector
(DLC) via a K-Line.
²communicates with other modules over the Con-
troller Area Network (CAN) C Bus.
²controls A/C clutch operation.
²controls EBL operation.
²controls water cycle valve operation.
IThe water cycle valve is a normally open valve,
meaning that it allows full engine coolant flow
through the heater core when no power is
delivered to the valve. The ATC controls the
valve with a pulse width signal. The lower the
percentage of the pulse width signal the more
the valve is open.
²controls Residual Heat Utilization (REST) func-
tion.
²controls blower motor operation, providing four
blower speeds (Low, M1, M2, & High).
²controls recirculation air solenoid valve.
²controls the mode door via cables.
²controls the main power supply to the Heater
Booster (if equipped).
²uses air inlet temperature sensor, air outlet tem-
perature sensor, and evaporator temperature
sensor input, as well as data from other modules
to maintain occupant comfort levels.
3.3.1.2 SYSTEM DIAGNOSTICS
Fault detection is through active and stored Diag-
nostic Trouble Codes (DTCs)
²DTCs are displayed by the DRBIIIt.
²Active DTCs are those which currently exist in
the system. The condition causing the fault must
be repaired in order to clear this type of DTC.
²Stored DTCs are those which occurred in the
system since the ATC Module received the last
9clear diagnostic info9message.
Testing Preparation & Diagnostics
Set the necessary system functions accordingly so
that all of the following prerequisites are met prior
to performing diagnostic tests on the ATC system:
5
GENERAL INFORMATION

RAIN SENSOR
DESCRIPTION
The rain sensor provides the primary input for the
optional automatic wiper system (Fig. 6). The rain
sensor is located on the inside of the windshield,
where it is concealed within the molded plastic trim
cover that snaps over the base of the rear view mir-
ror arm. The sensor fits within the center of a ring-
like molded plastic bracket that is glued to the inside
of the windshield glass and that also serves as the
support for the rear view mirror.
The rain sensor is contained within a circular
molded black plastic housing with a short pigtail
wire and a connector insulator containing three ter-
minal cavities that exits one side of the housing. This
pigtail connects the rain sensor to the vehicle electri-
cal system through a dedicated take out and connec-
tor of the overhead wire harness that extends from
above the headliner. A molded plastic trough routes
and conceals the pigtail wires on the inside of the
windshield between the rear view mirror base and
the headliner.
The windshield side of the rain sensor housing is
open, but covered with a clear gelatin-like material
that protects the internal electronic sensor circuitry
and serves as the lens for the InfraRed (IR) diodes
and photocells within the sensor housing. This gel
coating must never be touched or the rain sensor
function may be impaired and the unit rendered
unusable. The rain sensor cannot be adjusted or
repaired and, if damaged or faulty, the entire sensor
must be replaced. The sensor bracket and a rear viewmirror adhesive kit are available for separate service
replacement.
OPERATION
The rain sensor operates on battery current and a
clean ground received from the rain sensor control
module. The rain sensor contains InfraRed (IR)
diodes that direct IR light beams at the windshield
at an angle. When the windshield glass is dry, most
of this IR light is reflected back to the sensor, which
uses photocell receivers to measure the intensity of
the light. When moisture accumulates on the wind-
shield glass, much of the IR light is refracted away
from the photocell receivers. This causes changes in
the signal output of the rain sensor. The rain sensor
control module monitors the signal output from the
sensor and then controls the wiper motor speed and
wipe intervals accordingly.
It is important to note that the default condition
for the wiper system is automatic wipers Off; there-
fore, if no message is received from the rain sensor
by the rain sensor control module, the automatic wip-
ers will be disabled. If automatic wipers are disabled,
normal low and high speed continuous wiper opera-
tion are unaffected. Also, due to the low voltage
nature of the rain sensor signal and the impact that
minor fluctuations in this signal strength can have
on wiper operation, grounded shielding circuits are
provided at the roof and control module connectors to
control electrical induction into the sensor signal cir-
cuit.
The hard wired rain sensor circuits may be diag-
nosed using conventional diagnostic tools and meth-
ods. However, conventional diagnostic methods may
not prove conclusive in the diagnosis of the internal
circuitry or the optics of the rain sensor. Refer to the
appropriate wiring information.
STANDARD PROCEDURE
RAIN SENSOR BRACKET REPLACEMENT
The rain sensor fits within the center of a ring-like
molded plastic bracket that is glued to the inside of
the windshield glass and that also serves as the sup-
port for the rear view mirror arm. If the bracket
should come loose from the windshield, it must be
reinstalled using a rear view mirror adhesive kit and
the procedure that follows.
Fig. 6 Rain Sensor
1 - HEADLINER
2 - TROUGH
3 - WINDSHIELD
4 - RAIN SENSOR
5 - MIRROR
8R - 12 WIPERS/WASHERSVA