2005 MERCEDES-BENZ SPRINTER heating

(6) Properly align the radiator assembly and
install the front end cross member.
(7) Connect negative battery cable.
ENGINE BLOCK HEATER
REMOVAL
WARNING: RISK OF INJURY TO SKIN AND EYES
DUE TO SCALDING FROM HOT COOLANT. DO NOT
OPEN THE COOLING SYSTEM UNLESS THE TEM-
PERATURE IS BELOW 194ÉF (90ÉC). WEAR PRO-
TECTIVE CLOTHING AND EYE WEAR. RISK OF
POISONING IF COOLANT IS SWALLOWED. STORE
COOLANT IN PROPER AND APPROPRIATELY
MARKED CONTAINERS.
(1) Disconnect the negative battery cable.
(2) Drain the cooling system.
(3) Record the location and snip the wire ties.
(4) Unscrew the engine block heater from the core
plug hole and remove (Fig. 6).
INSTALLATION
(1) Screw the block heater into the appropriate
core hole (Fig. 6).
(2) Route the heater wiring harness away from
and interference and secure with wiring tie straps.
(3) Refill the cooling system.
(4) Connect the negative battery cable.
(5) Start the engine and inspect for leaks.
ENGINE COOLANT TEMP
SENSOR
DESCRIPTION
The ECM determines the operating temperature of
the engine by using the signal from the coolant tem-
perature sensor. The coolant temperature sensor has
a negative temperature coefficient (NTC) resistor
contained in the plastic housing. NTC means; the
higher the temperature, then the lower the resis-
tance. The ECM also uses the coolant temperature
sensor signal to calculate glow plug relay triggering.
If the coolant temperature sensor fails during opera-
tion, the ECM will switch on the cooling fan to pre-
vent engine overheating (A/C models only).
REMOVAL
WARNING: RISK OF INJURY TO SKIN AND EYES
FROM SCALDING WITH HOT COOLANT. RISK OF
POISONING FROM SWALLOWING COOLANT. DO
NOT OPEN COOLING SYSTEM UNLESS COOLANT
TEMPERATURE IS BELOW 90ÉC. OPEN CAP
SLOWLY TO RELEASE PRESSURE. STORE COOL-
ANT IN SUITABLE AND APPROPRIATELY MARKED
CONTAINER. WEAR PROTECTIVE GLOVES,
CLOTHES AND EYE WEAR.
(1) Disconnect negative battery cable.
(2) Remove engine cover (Refer to 9 - ENGINE -
REMOVAL).
(3) Partailly drain coolant system (Refer to 7 -
COOLING/ENGINE/COOLANT - STANDARD PRO-
CEDURE).
(4) Unplug coolant temperature sensor electrical
connector.
Fig. 6 ENGINE BLOCK HEATER
1 - ENGINE BLOCK HEATER
2 - CORE PLUG
3 - ENGINE MOUNT
4 - WIRING TIE STRAPS
7 - 14 ENGINEVA
RADIATOR FAN (Continued)

(2) Connect the wire harness connectors to the
central timer module.
(3) Install the screws that secure the central timer
module. Tighten the screws securely.
(4) Route the seat belt latch wire lead through the
hole in the closeout panel and position the panel
beneath the driver seat cushion
(5) Install the screws that secure the closeout
panel beneath the driver seat cushion. Tighten the
screws securely.
(6) Connect the wire harness connector to the seat
belt latch connector.
(7) Slide the driver seat to back to its original posi-
tion.
(8) Reconnect the negative battery cable.
CONTROLLER ANTILOCK
BRAKE
DESCRIPTION
The Controler Antilock Brake (CAB) is mounted to
the Hydraulic Control Unit (HCU) and operates the
ABS system.
REMOVAL
(1) Remove the negative battery cable from the
battery.
(2) Pull up on the CAB harness connector release
and remove connector.
(3) Remove the CAB mounting bolts.
(4) Remove the CAB from the HCU.
INSTALLATION
(1) Install CAB to the HCU.
(2) Install mounting bolts. Tighten to 2 N´m (16 in.
lbs.).
(3) Install the wiring harness connector to the
CAB and push down on the release to secure the con-
nector.
(4) Install negative battery cable to the battery.
ENGINE CONTROL MODULE
DESCRIPTION
The electronic control module (ECM) is mounted to
the left lower dash panel and consists of an electronic
printed circuit board which is designed as a multi-
layer board assembly fitted on both sides. The rout-
ing of the five wiring harness connectors at the ECM
connectors are split into interfering cables and sensi-
tive cables in order to achieve improved electromag-
netic compatibility. The ECM stores engine specific
data, monitors the connected sensor and analyzes
their measurement (Fig. 2).
Its task consists in controlling the following sys-
tems in line with the analysis of the input signals:
²Fuel Supply System
²Injected Quantity Control
²Emission Control System
²Charge Pressure Control
²Cruise Control
²A/C Compressor Shut-Off
²Pre-Heating Output Relay for the Glow Plugs
²Vehicle Theft
²Air Bag
²Monitors inputs/outputs, checks plausibility and
stores faults
²Share information with other control modules
²Diagnosis
If a sensor should fail, provided the fault is not
serious, the ECM will continue to operate the engine
in Limp-Home Mode (emergency mode) using a
default value for the missing signal. The ECM
ensures that continuing to operate the engine will
not cause damage or effect safety,otherwise a Engine
shut-off process will be carried out.Fig. 1 Central Timer Module
1 - DRIVER SEAT
2 - WIRE HARNESS CONNECTOR
3 - SCREW (2)
4 - CLOSEOUT PANEL
5 - CENTRAL TIMER MODULE
6 - WIRE HARNESS CONNECTOR (2)
7 - SCREW (2)
VAELECTRONIC CONTROL MODULES 8E - 3
CENTRAL TIMER MODULE (Continued)

HEATED SYSTEMS
TABLE OF CONTENTS
page page
HEATED SEATS
DESCRIPTION..........................1
OPERATION............................2
DIAGNOSIS AND TESTING - HEATED SEATS . . 2
DRIVER HEATED SEAT SWITCH
DESCRIPTION..........................2
OPERATION............................2
DIAGNOSIS AND TESTING - DRIVER HEATED
SEAT SWITCH.........................2
REMOVAL.............................3
INSTALLATION..........................3
HEATED SEAT ELEMENT
DESCRIPTION..........................3
OPERATION............................3
DIAGNOSIS AND TESTING - HEATED SEAT
ELEMENT............................3
HEATED SEAT RELAY
DESCRIPTION..........................4OPERATION............................4
DIAGNOSIS AND TESTING - HEATED SEAT
RELAY...............................4
REMOVAL.............................4
INSTALLATION..........................4
HEATED SEAT SENSOR
DESCRIPTION..........................4
DIAGNOSIS AND TESTING - HEATED SEAT
SENSOR.............................4
PASSENGER HEATED SEAT SWITCH
DESCRIPTION..........................5
OPERATION............................5
DIAGNOSIS AND TESTING - PASSENGER
HEATED SEAT SWITCH.................5
REMOVAL.............................5
INSTALLATION..........................5
HEATED SEATS
DESCRIPTION
Individually controlled, electrically heated front
seats are available factory-installed optional equip-
ment on this model. Vehicles with this option can be
visually identified by the two separate heated seat
switches mounted in the instrument panel. The
heated seat system allows the front seat driver and
passenger to select from two different levels of sup-
plemental electrical seat heating, or no seat heating
to suit their individual comfort requirements. The
heated seat system for this vehicle includes the fol-
lowing major components, which are described in fur-
ther detail later in this section:
²Heated Seat Elements- Four heated seat ele-
ments are used per vehicle, two for each front seat.
One heating element in the seat back and one in the
seat cushion. The heated seat sensor is integral to
the seat cushion heating element. The heated seat
elements are integral to the front seat and seat back
cushions. Refer to heated seat elements later in this
section for additional information.²Heated Seat Relay- One heated seat relay is
used per vehicle. The relay is located in the fuse
block and is responsible for distributing the voltage
(B+) to the heated seat elements.
²Heated Seat Sensors- Two heated seat sen-
sors are used per vehicle, one for each front seat. The
heated seat sensors are integral to each of the heated
seat element assemblies. Refer to heated seat sensor
later in this section for additional information.
²Heated Seat Switches- Two heated seat
switches are used per vehicle, one for each front seat.
The switches are mounted in the instrument panel.
Refer to heated seat switches later in this section for
additional information.
Hard wired circuitry connects the heated seat sys-
tem components to each other through the electrical
system of the vehicle. Refer to Wiring for additional
information. The wiring information includes wiring
diagrams, proper wire and connector repair proce-
dures, further details on wire harness routing and
retention, as well as pin-out and location views for
the various wire harness connectors, splices and
grounds.
VAHEATED SYSTEMS 8G - 1

REMOVAL
(1) Disconnect and isolate the negative battery
cable.
(2) Remove the gear selector bezel trim. Refer to
the Body section for the procedure.
(3) Remove the storage bin. Refer to the Body sec-
tion for the procedure.
(4) Remove the switch bezel retaining screw and
remove the switch bezel from the instrument panel.
Refer to the Body section for the procedure.
(5) Disconnect electrical connections.
(6) Working from the underside of the switch, gen-
tly rock the switch back and forth out of its mounting
location in the switch bezel.
INSTALLATION
(1) Install the heated seat switch in its mounting
location in the switch bezel.
(2) Connect electrical connections.
(3) Position the switch bezel and install the retain-
ing screw. Refer to the Body section for the proce-
dure.
(4) Install the storage bin. Refer to the Body sec-
tion for the procedure.
(5) Install the gear selector bezel trim. Refer to the
Body section for the procedure.
(6) Connect the negative battery cable.
HEATED SEAT ELEMENT
DESCRIPTION
The heated seat system includes two seat heating
elements in each front seat, one for the seat cushion
(Fig. 1) and the other for the seat back. All models
use two resistor wire heating elements for each seat
that are connected in series with the Heated Seat
Relay. The temperature sensor is a Negative Temper-
ature Coefficient (NTC) thermistor. One temperature
sensor is used for each seat, and it is located in the
seat cushion heating element for all models.
The seat heating elements are glued onto the seat
and seat back cushions. The heated seat elements
and the temperature sensor cannot be adjusted or
repaired and, if faulty or damaged a new seat assem-
bly must be installed.
OPERATION
The heated seat elements resist the flow of electri-
cal current. When battery current is passed through
the elements, the energy lost by the resistance of the
elements is released in the form of heat. The heated
seat temperature sensor is a NTC thermistor. When
the temperature of the seat cushion cover rises, the
resistance of the sensor decreases. The heated seat
relay uses this temperature sensor input to monitorthe temperature of the seat, and regulates the cur-
rent flow to the seat heating elements accordingly.
DIAGNOSIS AND TESTING - HEATED SEAT
ELEMENT
For complete circuit diagrams, refer toWiring.
NOTE: When checking heated seat elements for
continuity, be certain to move the heating element
being checked. Moving the element, such as sitting
in the seat will eliminate the possibility of an inter-
mittent open in the element which would only be
evident if the element was in a certain position.
Failure to check the element in various positions
could result in an incomplete test.
(1) Disconnect and isolate the battery negative
cable. Disconnect the heated seat element wire har-
ness connector from under the seat cushion. Check
for continuity between the seat heater driver circuit
and ground. There should be continuity, less than 7
ohms. If OK, go to Step 2. If not OK, replace the seat
assembly.
(2) Check for continuity between the seat heater
B+ driver circuit cavity and the seat back frame.
There should benocontinuity. If OK, heating ele-
ment is OK at this time. If not OK, replace the seat
assembly.
Fig. 1 Heated Seat Element - Typical
1 - Seat Back Wire Harness
2 - Heated Seat Wire Harness Connector
3 - Heated Seat Cushion Element
VAHEATED SYSTEMS 8G - 3
DRIVER HEATED SEAT SWITCH (Continued)

HEATED SEAT RELAY
DESCRIPTION
The heated seat relay is an electromechanical
device that switches 12v battery current to the
heated seat elements when the relay control coil is
energized. The heated seat relay is located in the
Fuse Block, under the drivers seat. The heated seat
relay is a International Standards Organization
(ISO) relay. Relays conforming to the ISO specifica-
tions have common physical dimensions, current
capacities, terminal patterns, and terminal functions.
The heated seat relay cannot be repaired or
adjusted and, if faulty or damaged, it must be
replaced.
OPERATION
The ISO relay consists of an electromagnetic coil, a
resistor or diode, and three (two fixed and one mov-
able) electrical contacts. The movable (common feed)
relay contact is held against one of the fixed contacts
(normally closed) by spring pressure. When the elec-
tromagnetic coil is energized, it draws the movable
contact away from the normally closed fixed contact,
and holds it against the other (normally open) fixed
contact. When the electromagnetic coil is de-ener-
gized, spring pressure returns the movable contact to
the normally closed position. The resistor or diode is
connected in parallel with the electromagnetic coil in
the relay, and helps to dissipate voltage spikes that
are produced when the coil is de-energized.
DIAGNOSIS AND TESTING - HEATED SEAT
RELAY
The heated seat relay is located in the Fuse Block,
under the drivers seat. Refer toWiringfor the loca-
tion of complete heated seat system wiring diagrams.
(1) Remove the heated seat relay from the fuse
block.
(2) A relay in the de-energized position should
have continuity between terminals 87A and 30, and
no continuity between terminals 87 and 30. If OK, go
to Step 3. If not OK, replace the faulty relay.
(3) Resistance between terminals 85 and 86 (elec-
tromagnet) should be 75   5 ohms. If OK, go to Step
4. If not OK, replace the faulty relay.
(4) Connect a battery to terminals 85 and 86.
There should now be continuity between terminals
30 and 87, and no continuity between terminals 87A
and 30. If OK, check the relay supply circuits. If not
OK, replace the faulty relay.
REMOVAL
(1) Disconnect and isolate the battery negative
cable.
(2) The heated seat relay is located in the fuse
block, under the drivers seat. Refer to wiring for
detailed location.
(3) Grasp the heated seat relay firmly and pull it
straight out from the fuse block. A slight rocking
motion will aid in removal.
INSTALLATION
(1) Grasp the heated seat relay firmly and push it
straight in the fuse block.
(2) Reconnect the battery negative cable.
HEATED SEAT SENSOR
DESCRIPTION
The heated seat temperature sensor is a Negative
Temperature Coefficient (NTC) thermistor. One tem-
perature sensor is used for each seat. The sensor is
located in the seat cushion heating element for all
models.
The heated seat sensor cannot be adjusted or
repaired and if it is found to be faulty, the complete
heated seat element must be replaced.
DIAGNOSIS AND TESTING - HEATED SEAT
SENSOR
For complete circuit diagrams, refer toWiring.
NOTE: Any resistance values (ohmsV) given in the
following text are supplied using the automatic
range generated by a FLUKETautomotive meter. If
another type of measuring device is used the val-
ues generated may not be the same as the results
shown here, or may have to be converted to the
range used here.
(1) Backprobe the heated seat relay wire harness
connector, do not disconnect. Using an voltmeter,
check the voltage of the seat temperature sensor
input cavity of the heated seat relay wire harness
connector. The seat sensor input voltage should be
between 1.7 volts and 3.0 volts with the system ON.
If OK, sensor is OK at this time. If not OK, replace
the faulty seat cushion heating element and sensor
assembly.
8G - 4 HEATED SYSTEMSVA

GLOW PLUG RELAY
DESCRIPTION
The glow plug relay supplies battery voltage to the
glow plug through a timed cycle that is related to
coolant temperature. The glow plug relay is located
under the battery. The purpose of a glow plug system
is to improve combustion for low emissions and to
achieve easy starting at low temperatures.
OPERATION
When the ignition key is turned to the ON position,
the glow plug output stage and pre-glow indicator
lamp are actuated by the ECM. The duration of the
signal depends on the coolant temperature. The glow
plug relay has processing that communicates with the
ECM. If no data exchange occurs at the triggering
stage, the preheating is switched off after 2 seconds.
Start glowing is initiated when the key is in the
start position. The glow plugs (R13±R17) continue to
be supplied with voltage. This makes it possible to
stabilize the cold starting speed. (After glowing is ini-
tiated when the starter reject speed is reached).
After the engine starts, the ECM determines the
afterglow period in line with coolant temperature. If
no signal is received from the coolant temperature
sensor, afterglow is maintained for thirty seconds.
The following aims are reached by the afterglow :²Improvement in warming-up properties
²
Prevention of white exhaust smoke after cold start
²Stabilizing of the cold starting speed
The glow plug output stage constantly signals the
current operating state and faults. The following are
faults detected and transmitted to the ECM :
²Open circuit at one or several glow plugs
²Short circuit in the glow plug circuit
²Relay fault
If the Glow plug relay detects an open circuit at a
glow plug, it is stored and indicated only once the
engine is running by the preglow indicator lamp com-
ing on for about one minute and a fault is stored in
the ECM. If a short circuit, a glow plug output stage
faulty or a temperature related switching off of out-
put stages is detected, the fault is stored and indi-
cated immediately by the preglow indicator lamp
coming on. Once the fault is no longer current, the
indicator is immediately switched off, but the fault is
stored in the ECM. If the fault is constantly current,
the preglow indicator lamp remains on until the igni-
tion is switched off.
DIAGNOSIS AND TESTING - GLOW PLUG
RELAYS
Refer to the appropriate Diesel Powertrain Diagno-
sis Manual for information on diagnosing the glow
plug relays.
Fig. 1 GLOW PLUG(S)
1 - GLOW PLUG
2 - WIRING HARNESS CONNECTOR3 - INTAKE MANIFOLD
4 - CYLINDER HEAD COVER
8I - 2 IGNITION CONTROLVA
GLOW PLUG (Continued)

8W-97 POWER DISTRIBUTION
TABLE OF CONTENTS
page page
POWER DISTRIBUTION
DESCRIPTION..........................1
OPERATION............................1
CIGAR LIGHTER OUTLET
DESCRIPTION..........................1
OPERATION............................2
DIAGNOSIS AND TESTING - CIGAR LIGHTER
OUTLET.............................2
REMOVAL.............................2
CIRCUIT BREAKER
DESCRIPTION..........................2
OPERATION............................2
DIAGNOSIS AND TESTING - CIRCUIT
BREAKER............................2
FUSE BLOCK #1
DESCRIPTION..........................2
OPERATION............................2
REMOVAL.............................3
INSTALLATION..........................3FUSE BLOCK #2
DESCRIPTION..........................3
OPERATION............................3
POWER DISTRIBUTION CENTER
DESCRIPTION..........................3
OPERATION............................3
POWER OUTLET
DESCRIPTION..........................3
OPERATION............................4
DIAGNOSIS AND TESTING - POWER OUTLET . 4
REMOVAL.............................4
INSTALLATION..........................4
RELAY
DESCRIPTION..........................4
OPERATION............................5
DIAGNOSIS AND TESTING - RELAY.........5
REMOVAL.............................5
INSTALLATION..........................5
POWER DISTRIBUTION
DESCRIPTION
This section describes the power distribution com-
ponents used on this model as well as the methods in
which battery voltage and charging system voltage is
distributed throughout the vehicle. The power distri-
bution system for this vehicle consists of the follow-
ing major components which are covered in further
detail later in this section:
²Fuseblock #1
²Fuseblock #2
²Power Distribution Center (PDC)
The power distribution system also incorporates
various types of circuit control and protection fea-
tures, including:
²Automatic resetting circuit breakers
²Blade-type fuses
²Cartridge fuses
²Relays
Following are general descriptions and theory of
operation for the major components in the power dis-
tribution system. Refer to Wiring for the location of
complete circuit diagrams for the various power dis-
tribution system components.
OPERATION
The power distribution system for this vehicle is
designed to provide safe, reliable, and centralized dis-
tribution points for the electrical current required to
operate all of the standard and optional factory-in-
stalled electrical and powertrain, chassis, safety,
security and convenience systems. At the same time,
the power distribution system was designed to pro-
vide easy access to these electrical distribution points
for the vehicle technician to use when conducting
diagnosis and repair of faulty circuits. The power dis-
tribution system can also prove useful for the addi-
tion of electrical circuits that may be required to
operate accessories that the vehicle owner may
choose to have installed in the aftermarket.
CIGAR LIGHTER OUTLET
DESCRIPTION
The cigar lighter outlet is installed in the instru-
ment panel, near the center of the instrument panel.
The cigar lighter outlet is secured by a snap fit
within the instrument panel.
The cigar lighter knob/heating element, and the
cigar lighter outlet are available for service. These
components cannot be repaired and, if faulty or dam-
aged, they must be replaced.
VA8W-97 POWER DISTRIBUTION 8W - 97 - 1

OPERATION
The cigar lighter consists of two major components:
a knob and heating element unit, and the cigar
lighter base or receptacle shell. The receptacle shell
is connected to ground, and an insulated contact in
the bottom of the shell is connected to battery cur-
rent. The cigar lighter receives battery voltage from a
fuse in the fuseblock only when the ignition switch is
in the Accessory or On positions.
The knob and heating element are encased within
a spring-loaded housing, which also features a sliding
protective heat shield. When the heating element is
inserted in the receptacle shell, the heating element
resistor coil is grounded through its housing to the
receptacle shell. If the cigar lighter knob is pushed
inward, the heat shield slides up toward the knob
exposing the heating element.
Two small spring-clip retainers are located on
either side of the insulated contact inside the bottom
of the receptacle shell. These clips engage and hold
the heating element against the insulated contact
long enough for the resistor coil to heat up and glow.
When the resistor coil becomes sufficiently heated,
excess heat radiates from the heating element caus-
ing the spring-clips to expand. Once the spring-clips
expand far enough to release the heating element,
the spring-loaded housing forces the knob and heat-
ing element to pop back outward to their relaxed
position. When the cigar lighter knob and element
are pulled out of the receptacle shell, the protective
heat shield slides downward on the housing so that
the heating element is recessed and shielded around
its circumference for safety.
DIAGNOSIS AND TESTING - CIGAR LIGHTER
OUTLET
For cigar lighter outlet diagnosis and testing pro-
cedures (Refer to 8 - ELECTRICAL/POWER DISTRI-
BUTION/POWER OUTLET - DIAGNOSIS AND
TESTING)
REMOVAL
For cigar lighter outlet removal procedure (Refer to
8 - ELECTRICAL/POWER DISTRIBUTION/POWER
OUTLET - REMOVAL).
CIRCUIT BREAKER
DESCRIPTION
Automatic resetting circuit breakers are used to
protect the power window voltage supply circuits.
These circuit breakers can protect the systems from a
short circuit, or from an overload condition caused by
an obstructed or stuck power window regulator or
switch.The circuit breaker cannot be repaired and, if
faulty or damaged, it must be replaced.
OPERATION
The circuit breaker contains a bi-metal strip sand-
wiched between two contacts forming the connection
in the circuit. An overload condition causes the
bi-metal strip to heat and bend to the open position,
disconnecting current flow to the circuit. Then as the
system overload or short circuit is removed, the
bi-metal strip cools, re-establishing contact to allow
current flow to the circuit.
DIAGNOSIS AND TESTING - CIRCUIT BREAKER
For complete circuit descriptions and diagrams,
refer toWiring.
(1) Locate the correct circuit breaker in the fuse-
block. Pull out the circuit breaker slightly, but be cer-
tain that the circuit breaker terminals still contact
the terminals in the fuseblock cavities.
(2) Connect the negative lead of a 12-volt DC volt-
meter to a good ground.
(3) With the voltmeter positive lead, check both
terminals of the circuit breaker for battery voltage.
If only one terminal has battery voltage, the circuit
breaker is faulty and must be replaced. If neither ter-
minal has battery voltage, repair the open circuit
from the Power Distribution Center as required.
FUSE BLOCK #1
DESCRIPTION
An electrical fuse block is concealed under the
driver side steering column. The fuse block serves to
distribute electrical current to many of the electrical
systems in the vehicle. The fuse block contains blade-
type mini fuses, relays and micro processors that
enable automatic control of some of the power distri-
bution circuits throughout the vehicle.
The molded plastic fuse block housing has an inte-
gral mounting bracket that is secured with screws to
the steering column. A finger recess is molded into
the cover for easy removal. A fuse layout map is
molded onto the back side of the cover to ensure
proper fuse identification.
The fuse block cannot be repaired, if the fuse block
is faulty or damaged or if any internal circuit is
faulty or damaged, the entire fuse block must be
replaced.
OPERATION
All of the circuits entering and leaving the fuse
block do so through the instrument panel wire har-
ness. Internal connection of all of the fuse block cir-
cuits is accomplished by an intricate combination of
8W - 97 - 2 8W-97 POWER DISTRIBUTIONVA
CIGAR LIGHTER OUTLET (Continued)