2006 MERCEDES-BENZ SPRINTER radio controls

radio (Fig. 7). The A/C-heater control contains a rota-
ry-type temperature control, a rotary-type mode con-
trol, a thumbwheel-type blower motor speed control
and an A/C mode push button switch and indicator
lamp. The A/C-heater control also features a push
button switch and indicator lamp for the residual
engine heat utilization (REST) function, cabin heater
or the heater booster (as equipped).
OPERATION
To control the interior temperature, the A/C-heater
control uses the actual values from the temperature
sensors and the CAN bus and compares them with
the nominal value of the temperature control switch.
The A/C-heater control is diagnosed using a DRBIIIt
scan tool. Refer to Body Diagnostic Procedures.
The A/C-heater control is diagnosed using a
DRBIIItscan tool. Refer to Body Diagnostic Proce-
dures.
The A/C-heater control cannot be adjusted or
repaired and, if faulty or damaged, it must be
replaced.
REMOVAL
WARNING: To avoid personal injury or death, on
vehicles equipped with airbags, disable the supple-
mental restraint system before attempting any
steering wheel, steering column, airbag, seat belt
tensioner, impact sensor, or instrument panel com-
ponent diagnosis or service. Disconnect and isolate
the battery negative (ground) cable, then wait two
minutes for the system capacitor to discharge
before performing further diagnosis or service. This
is the only sure way to disable the supplemental
restraint system. Failure to take the proper precau-
tions could result in accidental airbag deployment.(1) Disconnect and isolate the negative battery
cable.
(2) Remove the center bezel from the instrument
panel. (Refer to 23 - BODY/INSTRUMENT PANEL/
INSTRUMENT PANEL CENTER BEZEL -
REMOVAL).
(3) Remove the two screws that secure the A/C-
heater control to the instrument panel (Fig. 8).
(4) Pull the A/C-heater control away from the
instrument panel far enough to access the connec-
tions on the back of the control.
(5) Mark and disconnect the two control cables
from the A/C-heater control.
(6) Disconnect the two wiring harness connectors
from the A/C-heater control.
(7) If A/C-heater control is to be replaced, remove
the two mounting brackets from the A/C-heater con-
trol.INSTALLATION
(1) If removed, install the two mounting brackets
to the A/C-heater control.
(2) Connect the two wire harness connectors into
the back of the A/C-heater control.
(3) Connect the two control cables to the A/C-
heater control.
NOTE: Install the control cable of bottom adjust-
ment lever to the front adjustment wheel of the A/C-
heater control.
(4) Position the A/C-heater control into the instru-
ment panel.
Fig. 7 A/C-Heater Control
Fig. 8 A/C-Heater Control
1 - A/C-HEATER CONTROL
2 - CONTROL CABLE
3 - CONTROL CABLE
4 - WIRE HARNESS CONNECTOR
5 - WIRE HARNESS CONNECTOR
6 - MOUNTING BRACKET (2)
7 - SCREW (2)
VACONTROLS-FRONT 24 - 13

The external location of the sensor allows the sensor
to be removed or installed without disturbing the
refrigerant in the A/C system.
The evaporator temperature sensor is diagnosed by
performing the ATC Function Test using a DRBIIIt
scan tool. Refer to Body Diagnostic Procedures.
The evaporator temperature sensor cannot be
adjusted or repaired and, if faulty or damaged, it
must be replaced.
REMOVAL
(1) Disconnect and isolate the negative battery
cable.
(2) Remove the radio (Refer to 8 - ELECTRICAL/
AUDIO/RADIO - REMOVAL).
(3) Remove glove compartment.
(4) Remove cover from instrument cluster (Refer to
23 - BODY/INSTRUMENT PANEL/INSTRUMENT
PANEL TOP COVER - REMOVAL).
(5) Remove the instrument cluster (Refer to 8 -
ELECTRICAL/INSTRUMENT CLUSTER -
REMOVAL).
(6) Remove passenger side airbag.
(7) Remove cover above air nozzle on passenger
side.
(8) Remove speaker.
(9) Remove center section of instrument panel.
(10) Remove A/C-heater control from the instru-
ment panel (Refer to 24 - HEATING & AIR CONDI-
TIONING/CONTROLS/A/C HEATER CONTROL -
REMOVAL).
(11) Remove instrument panel top section.
(12) Remove electrical connections.
(13) Remove air bezels from instrument panel.
(14) Disconnect the wire harness connector from
evaporator temperature sensor (Fig. 19).
(15) Remove evaporator temperature sensor from
HVAC housing.
INSTALLATION
(1) Install the probe of the evaporator temperature
sensor between the fins of the A/C evaporator.
NOTE: The probe must not go into the same hole
(in the A/C evaporator ) that the probe was removed
from.
(2) Install the wire harness connector to the evap-
orator temperature sensor.
(3) Install the air bezels to the instrument panel.
(4) Install the electrical connections.
(5) Install the instrument panel top section (Refer
to 23 - BODY/INSTRUMENT PANEL/INSTRUMENT
PANEL TOP COVER - INSTALLATION).
(6) Install the A/C-heater control (Refer to 24 -
HEATING & AIR CONDITIONING/CONTROLS/A/C
HEATER CONTROL - INSTALLATION).
(7) Install the center section of the instrument
panel.
(8) Install the speaker (Refer to 8 - ELECTRICAL/
AUDIO/SPEAKER - INSTALLATION).
(9) Install the cover above the air nozzle on the
passenger side.
(10) Install the passenger side airbag.
(11) Install the instrument cluster (Refer to 8 -
ELECTRICAL/INSTRUMENT CLUSTER - INSTAL-
LATION).
(12) Install the cover to the instrument cluster.
(13) Install glove compartment.
(14) Install the radio (Refer to 8 - ELECTRICAL/
AUDIO/RADIO - INSTALLATION).
(15) Reconnect the negative battery cable.
Fig. 19 Evaporator Temperature Sensor
1 - WIRE HARNESS CONNECTOR
2 - EVAPORATOR TEMPERATURE SENSOR
24 - 20 CONTROLS-FRONTVA

INSTALLATION
(1) Carefully install the rear temperature sensor
onto the bracket located in the rear A/C evaporator
housing.
(2) Connect the temperature sensor wire harness
connector.
(3) Connect the wire harness connector to the rear
temperature sensor.
(4) Install the rear air filter (Refer to 24 - HEAT-
ING & AIR CONDITIONING/DISTRIBUTION -
REAR/AIR FILTER - INSTALLATION).
(5) Reconnect the negative battery cable.
SUPPRESSOR FILTER - REAR
BLOWER MOTOR
DESCRIPTION
The two interference suppression filters (Fig. 21)
for the two rear blower motors protects the rear A/C
control circuits and the vehicles electrical system
from voltage spikes which may be generated by the
two blower motors or the three rear blower motor
relays. The suppression filters also impede the prop-
agation of RF interference into the vehicles electrical
system by the rear blower motors to ensure interfer-
ence-free radio reception.
The rear blower motor suppression filters are
located near the rear blower motors in the rear A/Cevaporator housing.
OPERATION
The rear blower motor suppression filters provide
protection against transient interference signals or
similar interference to the electronic rear blower
motor circuits which can effect the performance of
Fig. 20 Rear Temperature Sensor
1 - REAR A/C EVAPORATOR HOUSING
2 - TEMPERATURE SENSOR3 - BRACKET
4 - WIRE HARNESS CONNECTOR
Fig. 21 Rear Blower Motor Suppression Filter
1 - REAR BLOWER MOTOR SUPPRESSION FILTER (2)
2 - WIRE CONNECTOR (TO BLOWER MOTOR)
3 - WIRE CONNECTOR (TO REAR A/C HARNESS)
4 - MOUNTING BRACKET
VACONTROLS - REAR 24 - 41

the rear A/C control module circuits and radio recep-
tion quality. The suppression filters for the rear
blower motors consist of capacitors and inductance
coils.
The rear blower motor suppression filters cannot
be repaired and, if faulty or damaged, they must be
replaced. Refer to the appropriate wiring information
for complete HVAC wiring diagrams.
REMOVAL
(1) Disconnect and isolate the negative battery
cable.
(2) Remove the cover from the rear A/C evaporator
housing (Refer to 24 - HEATING & AIR CONDI-
TIONING/DISTRIBUTION - REAR/A/C EVAPORA-
TOR COVER-REAR - REMOVAL).
(3) Disconnect the two wire harness connectors
from the rear blower motor suppression filter being
serviced (Fig. 22).
(4) Remove the screw that secures the each rear
blower motor suppression filter to the rear A/C evap-
orator housing and remove the suppression filters as
required.
24 - 42 CONTROLS - REARVA

INSTALLATION
(1) Position the rear blower motor suppression fil-
ter being serviced to the rear A/C evaporator hous-
ing.
(2) Install the screw that secures each rear blower
motor suppression filter to the rear A/C evaporator
housing. Tighten the screw(s) to 2 N´m (17 in. lbs.).
(3) Connect the two suppression filter wire har-
ness connectors.
(4) Install the cover onto the rear A/C evaporator
housing (Refer to 24 - HEATING & AIR CONDI-
TIONING/DISTRIBUTION - REAR/A/C EVAPORA-
TOR COVER-REAR - INSTALLATION).
(5) Reconnect the negative battery cable.
SUPPRESSOR FILTER - REAR
CONDENSER FAN
DESCRIPTION
The interference suppression filter (Fig. 23) for the
rear A/C condenser fan protects the rear A/C control
circuits and the vehicles electrical system from volt-
age spikes which may be generated by the rear con-
denser fan motor or the rear condenser fan relay. The
suppression filter also impedes the propagation of RF
interference into the vehicles electrical system by therear condenser fan to ensure interference-free radio
reception.
The rear condenser fan suppression filter is located
in the rear A/C condenser housing near the rear con-
denser fan.
Fig. 22 Rear Blower Motor Suppression Filter ± LH shown, RH similar
1 - REAR A/C EVAPORATOR HOUSING
2 - SUPPRESSION FILTER WIRE CONNECTOR
3 - BLOWER MOTOR WIRE CONNECTOR4 - SCREW
5 - REAR BLOWER MOTOR SUPPRESSION FILTER (2)
VACONTROLS - REAR 24 - 43

OPERATION
The rear condenser fan suppression filter provides
protection against transient interference signals or
similar interference to the electronic rear condenser
fan circuits which can effect the performance of the
rear A/C control module circuits and radio reception
quality. The suppression filter for the rear condenser
fan consist of capacitors and inductance coils.
The rear condenser fan suppression filter cannot be
repaired and, if faulty or damaged, it must be
replaced. Refer to the appropriate wiring information
for complete HVAC wiring diagrams.
REMOVAL
(1) Disconnect and isolate the negative battery
cable.
(2) Remove the cover from the rear A/C condenser
housing (Refer to 24 - HEATING & AIR CONDI-
TIONING/DISTRIBUTION - REAR/A/C CON-
DENSER COVER-REAR - REMOVAL).
(3) Disconnect the two wire harness connectors
from the rear condenser fan suppression filter (Fig.
24).
(4) Remove the rear condenser fan (Refer to 24 -
HEATING & AIR CONDITIONING/PLUMBING/
REAR A/C CONDENSER FAN - REMOVAL).
(5) Remove the two bolts, washers and nuts that
secure the rear condenser fan suppression filter to
the rear A/C condenser housing and remove the sup-
pression filter.
INSTALLATION
(1) Position the rear condenser fan suppression fil-
ter to the rear A/C condenser housing.
(2) Install the two bolts, washers and nuts that
secure the rear condenser fan suppression filter to
the rear A/C condenser housing. Tighten the bolts to
5 N´m (44 in. lbs.).
(3) Install the rear condenser fan (Refer to 24 -
HEATING & AIR CONDITIONING/PLUMBING/
REAR A/C CONDENSER FAN - INSTALLATION).
(4) Connect the wiring harness connectors to the
rear condenser fan suppression filter and the rear
condenser fan.
(5) Install the cover onto the rear A/C condenser
housing (Refer to 24 - HEATING & AIR CONDI-
TIONING/DISTRIBUTION - REAR/A/C CON-
DENSER COVER - INSTALLATION).
(6) Reconnect the negative battery cable.
Fig. 23 Rear Condenser Fan Suppression Filter
1 - REAR CONDENSER FAN SUPPRESSION FILTER
2 - WIRE CONNECTOR (TO CONDENSER FAN)
3 - MOUNTING BRACKET
4 - WIRE CONNECTOR (TO REAR A/C HARNESS)
Fig. 24 Rear Condenser Fan Suppression Filter
1 - REAR A/C CONDENSER HOUSING
2 - CONDENSER FAN WIRE CONNECTOR
3 - BOLT, WASHER AND NUT (2)
4 - SUPPRESSION FILTER WIRE CONNECTOR
5 - REAR CONDENSER FAN SUPPRESSION FILTER
24 - 44 CONTROLS - REARVA

1.0 INTRODUCTION
The procedures contained in this manual include
all of the specifications, instructions, and graphics
needed to diagnose NAG1 Electronic Automatic
Transmission and Shift Lever Assembly problems.
The diagnostics in this manual are based on the
failure condition or symptom being present at the
time of diagnosis.
When repairs are required, refer to the appropri-
ate volume of the service information for the proper
removal and repair procedure.
READ THIS MANUAL BEFORE TRYING TO
DIAGNOSE A VEHICLE TROUBLE CODE.
Diagnostic procedures change every year. New
diagnostic systems may be added and/or carryover
systems may be enhanced. It is recommended that
you review the entire manual to become familiar
with all new and changed diagnostic procedures.
1.1 SYSTEM COVERAGE
This diagnostic procedures manual covers all
Sprinter (VA) equipped with a NAG1 Automatic
Transmission.
1.2 SIX -STEP TROUBLESHOOTING
PROCEDURE
Diagnosis of the NAG1 electronic transmission is
done in six basic steps:
Verification of complaint
Verification of any related symptoms
Symptom analysis
Problem isolation
Repair of isolated problem
Verification of proper operation
2.0 IDENTIFICATION OF
SYSTEM
The NAG1 Transmission family can be identified
by the presence of a 13 pin electrical connector, with
a bayonet lock on the right hand side of the trans-
mission. The connector is oriented horizontally.
3.0 SYSTEM DESCRIPTION AND
FUNCTIONAL OPERATION
3.1 GENERAL DESCRIPTION
The NAG1 electronic transmission is an electron-
ically controlled five speed transmission with a
controlled slip torque converter. The NAG1 elec-tronic transmission is a conventional transmission
in that it uses hydraulically applied clutches to shift
a planetary gear train. However, the electronic
control system replaces many of the mechanical and
hydraulic components used in conventional trans-
mission valve bodies.
The ratios for the gear stages are obtained by 3
planetary gear sets. Fifth Gear is designed as an
Overdrive with a high speed ratio. The gears are
actuated electronically/hydraulically. The electronic
control system enables precise adaptation of pres-
sures to the respective operating conditions and to
the engine output during a shift phase, which
results in a significant improvement in shift qual-
ity.
3.2 FUNCTIONAL OPERATION
The NAG1 electronic transmission has a fully
adaptive control system. The system performs its
functions based on continuous real-time sensor and
switch feedback information. In addition the TCM
receives information from the Shift Lever Assembly,
ECM (engine management) and ABS (chassis sys-
tems) controllers over the CAN bus. The CAN bus is
a high speed communication bus that allows real
time control capability between various controllers.
Most messages are sent every 20 milliseconds, this
means critical information can be shared between
the Transmission, Shifter, Engine and ABS control-
lers. The CAN bus is a two wire bus with aCAN C
Bus (+) circuitand aCAN C Bus (-) circuit. The
CAN bus uses a twisted pair of wires in the harness
to reduce the potential of radio and noise interfer-
ence. The CAN bus also uses a 120 ohm terminating
resistor in both the ECM and Sentry Key Remote
Entry Module (SKREEM) modules. The module
terminating resistance is measured across both
CAN bus circuits at the ECM or SKREEM module.
The control system automatically adapts to
changes in engine performance, vehicle speed, and
transmission temperature variations to provide
consistent shift quality. The control system ensures
that clutch operation during upshifting and down-
shifting is more responsive without increased
harshness. The TCM controls the actuation of sole-
noid valves for modulating shift pressure and gear
change. The required pressure level is calculated
from the load condition, engine speed. Power for the
transmission system is supplied through the Trans-
mission Relay. The TCM is located in the under the
drivers seat of the vehicle.
The Transmission Control Module (TCM) contin-
uously checks for electrical problems, mechanical
problems, and some hydraulic problems. When a
problem is sensed, the TCM stores a diagnostic
trouble code (DTC). Some of these codes cause the
transmission to go into9limp-in9or9default9mode.
1
GENERAL INFORMATION