2006 MERCEDES-BENZ SPRINTER relay

second time will turn the heated seat to Off. This
same process is repeated for High heat setting. The
heated seats will automatically return to the Off
mode anytime the vehicle ignition switch is turned
Off.
Both switches provide separate hard wire inputs to
the Heated Seat Relay to indicate the selected mode.
The Heated Seat Relay responds to the heated seat
switch messages by controlling the output to the seat
heater elements of the selected seat.
DIAGNOSIS AND TESTING - PASSENGER
HEATED SEAT SWITCH
For circuit description and diagrams, refer toWir-
ing.
(1) Inspect the Heated Seat Switches for apparent
damage or sticking/binding and replace if required.
Refer to Heated Seat Switch Removal and Installa-
tion in this section.
(2) Replace the heated seat switch with a known
good unit and retest the heated seat system.
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.
8G - 14 HEATED SEATSVA

IGNITION CONTROL
TABLE OF CONTENTS
page page
IGNITION CONTROL
OPERATION - GLOW PLUG................1
SPECIAL TOOLS........................1
GLOW PLUG
REMOVAL.............................1
INSTALLATION..........................1GLOW PLUG RELAY
DESCRIPTION..........................1
OPERATION............................2
DIAGNOSIS AND TESTING - GLOW PLUG
RELAYS..............................2
IGNITION CONTROL
OPERATION - GLOW PLUG
Pre - Glowing
With the key in the On position, the glow plug out-
put stage and the indicator lamp are actuated by the
ECM. The pre-heating time is calculated by the ECM
in line with the coolant temperature. The glow plug
output stage switches the current through the glow
plugs. The glow plug indicator lamp goes out after a
pre-glow period has elapsed. Component or cable fail-
ures in the pre-glow system are indicated by the glow
plug lamp and stored in the ECM.
Glow Output Stage
With the ignition key in the On position a signal is
transmitted from the ECM to the glow plug output
stager. If no data is exchanged with the ECM the
glow plug stage is terminated after two seconds. The
glow plug out put stage constantly signals the cur-
rent operating state (ON/OFF) and any system
faults. The following faults are recognized by the out
put stage and transmitted to the ECM:
²Open circuit in one or more of the glow plug
leads
²Short circuit in the glow plug circuit
²Out put stage fault or temperature related shut-
off
If a failure in the glow plug system occurs, the
glow plug indicator lamp will be illuminated only as
long as the fault is current. If the failure is no longer
present, the glow plug indicator lamp will be
switched off but a code will be stored in the ECM.
After Glow
Once the engine has started, the ECM determines
the after glow time depending on cooling tempera-
ture. During this time the glow plugs continue to be
actuated by the glow plug output stage. This results
in improved smooth running after a cold start and
improved warming up properties, elimination of blueexhaust after a cold start up and a more stable cold
starting speed.
If no signal is received from the coolant tempera-
ture sensor the signal from the oil sensor is used as a
substitute.
SPECIAL TOOLS
GLOW PLUG
REMOVAL
(1) Disconnect the negative battery cable.
(2) Remove the engine cover.
(3) Use special tool #9286 pliers to unplug the
glow plug wiring harness connector(s) at the glow
plug.
(4) Remove the glow plug(s) (Fig. 1).
INSTALLATION
(1) Screw glow plug(s) into cylinder head and
tighten to 12 N´m (115 lbs. in) (Fig. 1).
(2) Connect the glow plug wiring harness connec-
tor(s)
(3) Install the engine cover.
(4) Connect negative battery cable.
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
GLOW PLUG PLIERS
VAIGNITION CONTROL 8I - 1

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 posi-
tion, the glow plug output stage and pre-glow indica-
tor 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 trig-
gering 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
²Prevention 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 - ENGINE COVER
8I - 2 IGNITION CONTROLVA

Located between the rear cover and the cluster
hood is the cluster housing. The molded plastic clus-
ter housing serves as the carrier for the cluster elec-
tronic circuit board and circuitry, the cluster
connector receptacles, the gauges, a Light Emitting
Diode (LED) for each cluster indicator and general
illumination lamp, the multi-function indicator LCD
unit, electronic tone generators, the cluster overlay,
the gauge pointers, the multi-function indicator
switches and the four switch push buttons.
The cluster overlay is a laminated plastic unit. The
dark, visible, outer surface of the overlay is marked
with all of the gauge dial faces and graduations, but
this layer is also translucent. The darkness of this
outer layer prevents the cluster from appearing clut-
tered or busy by concealing the cluster indicators
that are not illuminated, while the translucence of
this layer allows those indicators and icons that are
illuminated to be readily visible. The underlying
layer of the overlay is opaque and allows light from
the LED for each of the various indicators and illu-
mination lamps behind it to be visible through the
outer layer of the overlay only through predeter-
mined cutouts. A rectangular opening in the overlay
at the base of the speedometer provides a window
through which the illuminated multi-function indica-
tor LCD unit can be viewed.
Several versions of the EMIC module are offered
on this model. These versions accommodate all of the
variations of optional equipment and regulatory
requirements for the various markets in which the
vehicle will be offered. The microprocessor-based
EMIC utilizes integrated circuitry, Electrically Eras-
able Programmable Read Only Memory (EEPROM)
type memory storage, information carried on the
Controller Area Network (CAN) data bus, along with
several hard wired analog and multiplexed inputs to
monitor systems, sensors and switches throughout
the vehicle.
In response to those inputs, the hardware and soft-
ware of the EMIC allow it to control and integrate
many electronic functions and features of the vehicle
through both hard wired outputs and the transmis-
sion of electronic message outputs to other electronic
modules in the vehicle over the CAN data bus. (Refer
to 8 - ELECTRICAL/ELECTRONIC CONTROL
MODULES/COMMUNICATION - DESCRIPTION -
CAN BUS).
Besides typical instrument cluster gauge and indi-
cator support, the electronic functions and features
that the EMIC supports or controls include the fol-
lowing:
²Active Service System- In vehicles equipped
with the Active Service SYSTem (ASSYST) engine oil
maintenance indicator option, the EMIC electronic
circuit board includes a second dedicated micropro-
cessor. This second microprocessor evaluates various
data including time, mileage, and driving conditionsto calculate the required engine oil service intervals,
and provides both visual and audible alerts to the
vehicle operator when certain engine oil maintenance
services are required.
²Audible Warnings- The EMIC electronic cir-
cuit board is equipped with an audible tone generator
and programming that allows it to provide various
audible alerts to the vehicle operator, including buzz-
ing and chime tones. An audible contactless elec-
tronic relay is also soldered onto the circuit board to
produce audible clicks that is synchronized with turn
signal indicator flashing to emulate the sounds of a
conventional turn signal or hazard warning flasher.
These audible clicks can occur at one of two rates to
emulate both normal and bulb-out turn or hazard
flasher operation. (Refer to 8 - ELECTRICAL/
CHIME/BUZZER - DESCRIPTION).
²Panel Lamps Dimming Control- The EMIC
provides a hard wired 12-volt Pulse-Width Modulated
(PWM) output that synchronizes the dimming level
of all panel lamps dimmer controlled lamps with that
of the cluster general illumination lamps and multi-
function indicator.
The EMIC houses four analog gauges and has pro-
visions for up to nineteen indicators (Fig. 3). The
EMIC includes the following analog gauges:
²Coolant Temperature Gauge
²Fuel Gauge
²Speedometer
²Tachometer
The EMIC includes provisions for the following
indicators (Fig. 3):
²Airbag (SRS) Indicator
²Antilock Brake System (ABS) Indicator
²Brake Indicator
²Brake Wear Indicator
²Charging Indicator
²Clogged Fuel Filter Indicator
²Constant Engine Speed (ADR) Indicator
²Coolant Low Indicator
²Electronic Stability Program (ESP) Indica-
tor
²High Beam Indicator
²Low Fuel Indicator
²Malfunction Indicator Lamp (MIL)
²Multi-Function Indicator (LCD)
²Park Brake Indicator
²Seatbelt Indicator
²Traction Control (ASR) Indicator
²Traction Control (ASR) Malfunction Indica-
tor
²Turn Signal (Right and Left) Indicators
²Washer Fluid Indicator
²Wait-To-Start Indicator
²Water-In-Fuel Indicator
VAINSTRUMENT CLUSTER 8J - 3

procedures, 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.
The EMIC modules for this model are serviced only
as complete units. The EMIC module cannot be
adjusted or repaired. If a gauge, an LED indicator,
the multi-fuction indicator LCD unit, an electronic
tone generator, the electronic circuit board, the cir-
cuit board hardware, the cluster overlay, the cluster
housing, the cluster hood, the cluster lens, or the
cluster rear cover are damaged or faulty, the entire
EMIC module must be replaced.
OPERATION
The ElectroMechanical Instrument Cluster (EMIC)
is designed to allow the vehicle operator to monitor
the conditions of many of the vehicle components and
operating systems. The gauges, meters and indicators
in the EMIC provide valuable information about the
powertrain, fuel and emissions systems, cooling sys-
tem, lighting systems, safety systems and many
other convenience items. The EMIC is installed in
the instrument panel so that all of these monitors
can be easily viewed by the vehicle operator when
driving, while still allowing relative ease of access for
service. The microprocessor-based EMIC hardware
and software uses various inputs to control the
gauges and indicators visible on the face of the clus-
ter. Some of these inputs are hard wired, but many
are in the form of electronic messages that are trans-
mitted by other electronic modules over the Control-
ler Area Network (CAN) data bus network. (Refer to
8 - ELECTRICAL/ELECTRONIC CONTROL MOD-
ULES/COMMUNICATION - OPERATION).
The EMIC microprocessor smooths the input data
using algorithms to provide gauge readings that are
accurate, stable and responsive to operating condi-
tions. These algorithms are designed to provide
gauge readings during normal operation that are con-
sistent with customer expectations. However, when
abnormal conditions exist such as high coolant tem-
perature, the algorithm can drive the gauge pointer
to an extreme position and the microprocessor can
sound a chime through the on-board audible tone
generator to provide distinct visual and audible indi-
cations of a problem to the vehicle operator. The
instrument cluster circuitry also provides audible
turn signal and hazard warning support by emulat-
ing the ªtickingº sound associated with a conven-
tional electro-mechanical flasher using a contactless
relay. The relay will also provide an indication of a
turn signal failure by sounding at double the usual
frequency. Each audible warning is provided to the
vehicle operator to supplement a visual indication.
The EMIC circuitry operates on battery current
received through a non-switched fused B(+) circuit,
and on a fused ignition switch output circuit. TheEMIC circuitry is grounded through a ground circuit
and take out of the frame wire harness with an eye-
let terminal connector that is secured to a stud by a
nut at a ground location on the dash panel just for-
ward of the instrument cluster. Separate switched
ground inputs from the key-in ignition switch and
the front door jamb switches provide wake-up signals
to the EMIC circuitry. This arrangement allows the
EMIC to provide some features regardless of the igni-
tion switch position, while other features will operate
only with the ignition switch in the On position.
Proper diagnosis and testing of the EMIC, the
CAN data bus, the data bus electronic message
inputs to and outputs from the EMIC, as well as the
retrieval or erasure of a Diagnostic Trouble Code
(DTC) requires the use of a diagnostic scan tool.
Refer to the appropriate diagnostic information. See
the owner's manual in the vehicle glove box for more
information on the features, use and operation of the
EMIC.
GAUGES
All gauges receive battery current through the
EMIC circuitry only when the instrument cluster
detects the ignition switch is in the On position. With
the ignition switch in the Off position, battery cur-
rent is not supplied to any gauges and the EMIC cir-
cuitry is programmed to move all of the gauge
needles back to the low end of their respective scales.
Therefore, the gauges do not accurately indicate any
vehicle condition unless the ignition switch is in the
On position.
All of the EMIC gauges are air core magnetic
units. Two fixed electromagnetic coils are located
within each gauge. These coils are wrapped at right
angles to each other around a movable permanent
magnet. The movable magnet is suspended within
the coils on one end of a pivot shaft, while the gauge
needle is attached to the other end of the shaft. One
of the coils has a fixed current flowing through it to
maintain a constant magnetic field strength. Current
flow through the second coil changes, which causes
changes in its magnetic field strength. The current
flowing through the second coil is changed by the
EMIC circuitry in response to messages received over
the CAN data bus. The gauge needle moves as the
movable permanent magnet aligns itself to the
changing magnetic fields created around it by the
electromagnets.
Proper diagnosis and testing of the gauges, the
CAN data bus and the electronic data bus message
inputs to the EMIC that control each gauge require
the use of a diagnostic scan tool. Refer to the appro-
priate diagnostic information. Specific operation
details for each gauge may be found elsewhere in
this service information.
VAINSTRUMENT CLUSTER 8J - 5

INDICATORS
Indicators are located in various positions within
the EMIC and are all connected to the EMIC elec-
tronic circuit board. The ambient temperature indica-
tor (optional), brake indicator, brake wear indicator,
charging indicator, coolant low indicator, high beam
indicator, low fuel indicator, park brake indicator,
seatbelt indicator, turn signal indicators, and washer
fluid indicator operate based upon hard wired inputs
to the EMIC. The airbag (SRS) indicator is normally
controlled by a hard wired input from the Airbag
Control Module (ACM); however, if the EMIC sees an
abnormal or no input from the ACM, it will automat-
ically turn the airbag indicator On until the hard
wired input from the ACM has been restored. The
Malfunction Indicator Lamp (MIL) is normally con-
trolled by CAN data bus messages from the Engine
Control Module (ECM); however, if the EMIC loses
CAN data bus communication, the EMIC circuitry
will automatically turn the MIL on until CAN data
bus communication is restored. The EMIC uses CAN
data bus messages from the ECM, the ACM, and the
Controller Antilock Brake to control all of the
remaining indicators.
The various EMIC indicators are controlled by dif-
ferent strategies; some receive battery feed from the
EMIC circuitry and have a switched ground, while
others are grounded through the EMIC circuitry and
have a switched battery feed. However, all indicators
are completely controlled by the EMIC microproces-
sor based upon various hard wired and electronic
message inputs. Except for the indications provided
by the multi-function indicator Liquid Crystal Dis-
play (LCD) unit, all indicators are illuminated at a
fixed intensity, which is not affected by the selected
illumination intensity of the EMIC general illumina-
tion lamps.
The hard wired indicator inputs may be diagnosed
using conventional diagnostic methods. However,
proper testing of the EMIC circuitry and the CAN
bus message controlled indicators requires the use of
a diagnostic scan tool. Refer to the appropriate diag-
nostic information. Specific details of the operation
for each indicator may be found elsewhere in this
service information.
CLUSTER ILLUMINATION
The EMIC has several general illumination lamps
that are illuminated when the exterior lighting is
turned on with the multi-function switch. The illumi-
nation intensity of these lamps is adjusted by a dim-
ming level input received from the multi-function
indicator ª+º (plus) and ª±º (minus) switch push but-
tons that extend through the lower edge of the clus-
ter lens below the right end of the multi-function
indicator. When the exterior lighting is turned Off,
the display is illuminated at maximum brightness.
When the exterior lighting is turned On and thetransmission gear selector is in the Park position,
depressing the plus switch push button brightens the
display lighting, and depressing the minus switch
push button dims the display lighting. The EMIC
also provides a Pulse-Width Modulated (PWM) panel
lamps dimmer output that can be used to synchro-
nize the illumination lighting levels of external illu-
mination lamps (up to about 23 to 30 watts) with
that of the EMIC.
The hard wired multi-function switch input and
the EMIC panel lamps dimmer output may be diag-
nosed using conventional diagnostic methods. How-
ever, proper testing of the PWM control of the EMIC
and the electronic dimming level inputs from the
multi-function indicator push buttons requires the
use of a diagnostic scan tool. Refer to the appropriate
diagnostic information.
INPUT AND OUTPUT CIRCUITS
HARD WIRED INPUTS
The hard wired inputs to the EMIC include the fol-
lowing:
NOTE: Final approved circuit names were not yet
available at the time this information was compiled.
²Airbag Indicator Driver
²Ambient Temperature Sensor Signal
(Optional)
²Brake Wear Indicator Sense
²Charging Indicator Driver
²Coolant Level Switch Sense
²Front Door Jamb Switch Sense
²Fuel Level Sensor Signal
²Fused B(+)
²Fused Ignition Switch Output
²High Beam Indicator Driver
²Key-In Ignition Switch Sense
²Left Turn Signal
²Park Brake Switch Sense
²Right Turn Signal
²Seat Belt Switch Sense
²Washer Fluid Switch Sense (Optional)
Refer to the appropriate wiring information for
additional details.
HARD WIRED OUTPUTS
The hard wired outputs of the EMIC include the
following:
²Engine Running Relay Control
²Panel Lamps Driver
Refer to the appropriate wiring information for
additional details.
8J - 6 INSTRUMENT CLUSTERVA

TRACTION CONTROL MAL-
FUNCTION INDICATOR
DESCRIPTION
A traction control (ASR) malfunction indicator is
standard equipment on all instrument clusters. The
traction control malfunction indicator is located near
the lower edge of the instrument cluster, to the right
of the multi-function indicator display. The traction
control malfunction indicator consists of an icon that
graphically depicts a tire and two skid marks
imprinted within a rectangular cutout in the opaque
layer of the instrument cluster overlay. The dark
outer layer of the overlay prevents the indicator from
being clearly visible when it is not illuminated. An
amber Light Emitting Diode (LED) behind the cutout
in the opaque layer of the overlay causes the icon to
appear silhouetted against an amber field through
the translucent outer layer of the overlay when the
indicator is illuminated from behind by the LED,
which is soldered onto the instrument cluster elec-
tronic circuit board. The traction control malfunction
indicator is serviced as a unit with the instrument
cluster.
OPERATION
The traction control (ASR) malfunction indicator
gives the vehicle operator an indication when the
traction control system is faulty or inoperative. This
indicator is controlled by a transistor on the instru-
ment cluster circuit board based upon cluster pro-
gramming and electronic messages received by the
cluster from the Controller Antilock Brake (CAB)
over the Controller Area Network (CAN) data bus.
The traction control malfunction indicator Light
Emitting Diode (LED) is completely controlled by the
instrument cluster logic circuit, and that logic will
only allow this indicator to operate when the instru-
ment cluster detects that the ignition switch is in the
On position. Therefore, the LED will always be off
when the ignition switch is in any position except
On. The LED only illuminates when it is provided a
path to ground by the instrument cluster transistor.
The instrument cluster will turn on the traction con-
trol malfunction indicator for the following reasons:
²Bulb Test- Each time the ignition switch is
turned to the On position the traction control indica-
tor is illuminated as a bulb test until the engine is
started.
²Traction Control (ASR) Malfunction Indica-
tor Lamp-On Message- Each time the cluster
receives a traction control malfunction indicator
lamp-on message from the CAB, the indicator will be
illuminated. The indicator remains illuminated until
the cluster receives a lamp-off message from the
CAB, or until the ignition switch is turned to the Off
position, whichever occurs first.The CAB continually monitors the traction control
(ASR) system circuits and sensors to decide whether
the system is in good operating condition. The CAB
then sends the proper lamp-on or lamp-off messages
to the instrument cluster. If the CAB sends a
lamp-on message after the bulb test, it indicates that
the CAB has detected a system malfunction and that
the traction control (ASR) system has become inoper-
ative. The CAB will store a Diagnostic Trouble Code
(DTC) for any malfunction it detects. In addition, if
the traction control malfunction indicator is illumi-
nated, the CAB will deactivate an activated traction
control system and engine power output may be
reduced. See the owner's manual in the vehicle glove
box for more information on the features, use, activa-
tion and deactivation of the traction control (ASR)
system. For proper diagnosis of the traction control
system, the CAB, the CAN data bus, or the electronic
message inputs to the instrument cluster that control
the traction control malfunction indicator, a diagnos-
tic scan tool is required. Refer to the appropriate
diagnostic information.
TURN SIGNAL INDICATOR
DESCRIPTION
Two turn signal indicators, one right and one left,
are standard equipment on all instrument clusters.
The turn signal indicators are located near the upper
edge of the instrument cluster, one to each side of the
speedometer. Each turn signal indicator consists of a
arrow-shaped cutout of the International Control and
Display Symbol icon for ªTurn Warningº in the
opaque layer of the instrument cluster overlay. The
dark outer layer of the overlay prevents these icons
from being clearly visible when they are not illumi-
nated. A green Light Emitting Diode (LED) behind
each turn signal indicator cutout in the opaque layer
of the overlay causes the icon to appear in green
through the translucent outer layer of the overlay
when the indicator is illuminated from behind by the
LED, which is soldered onto the instrument cluster
electronic circuit board. The turn signal indicators
are serviced as a unit with the instrument cluster.
OPERATION
The turn signal indicators give an indication to the
vehicle operator that the turn signal (left or right
indicator flashing) or hazard warning (both left and
right indicators flashing) have been selected and are
operating. These indicators are controlled by transis-
tors on the instrument cluster electronic circuit board
based upon the cluster programming and a hard
wired input received by the cluster from the turn sig-
nal relay through the turn signal and hazard warn-
ing switch circuitry of the multi-function switch on
VAINSTRUMENT CLUSTER 8J - 27

the left and right turn signal circuits. Each turn sig-
nal indicator Light Emitting Diode (LED) is com-
pletely controlled by the instrument cluster logic
circuit, and that logic will allow this indicator to
operate whenever the instrument cluster receives a
battery current input on the fused B(+) circuit.
Therefore, each LED can be illuminated regardless of
the ignition switch position. The LED only illumi-
nates when it is provided a path to ground by the
instrument cluster transistor. The instrument cluster
will turn on the turn signal indicators for the follow-
ing reasons:
²Turn Signal Input- Each time the cluster
detects a turn signal input from the turn signal relay
through the closed turn signal switch circuitry of the
multi-function switch on the hard wired left or right
turn signal circuit, the requested turn signal lamps
and turn signal indicator will be flashed on and off,
and a contactless relay soldered onto the cluster elec-
tronic circuit board will produce a clicking sound to
emulate a conventional turn signal flasher. The turn
signals and the turn signal indicators continue to
flash on and off until the turn signal switch circuitry
of the multi-function switch is opened, or until the
ignition switch is turned to the Off position, which-
ever occurs first.
²Hazard Warning Input- Each time the cluster
detects a hazard warning input from the turn signal
relay through the closed hazard warning switch cir-
cuitry of the multi-function switch on the hard wired
left and right turn signal circuits, all of the turn sig-
nal lamps and both turn signal indicators will be
flashed on and off, and a contactless relay soldered
onto the cluster electronic circuit board will produce
a clicking sound to emulate a conventional hazard
warning flasher. The turn signals and the turn signal
indicators continue to flash on and off until the haz-
ard warning switch circuitry of the multi-function
switch is opened.
An electronic wipers, turn signals and engine start
control module located within the fuse block beneath
the steering column monitors the turn signal circuits
and controls the flash rate of the turn signal relay.
The instrument cluster continually monitors the
right and left turn signal circuits to determine the
proper turn signal and hazard warning indicator
operation, then flashes the proper turn signal indica-
tors and the contactless relay on and off accordingly.
The multi-function switch, the turn signal relay and
the left and right turn signal circuits to the instru-
ment cluster can be diagnosed using conventional
diagnostic tools and methods. For proper diagnosis of
the wipers, turn signals and engine start control
module within the fuse block or the instrument clus-
ter circuitry that controls the turn signal indicators
and the contactless relay, a diagnostic scan tool is
required. Refer to the appropriate diagnostic infor-
mation.WAIT - TO - START INDICATOR
DESCRIPTION
A wait-to-start indicator is standard equipment in
all instrument clusters. The wait-to-start indicator is
located near the lower edge of the instrument cluster,
to the right of the multi-function indicator display.
The wait-to-start indicator consists of the Interna-
tional Control and Display Symbol icon for ªDiesel
Preheatº imprinted within a rectangular cutout in
the opaque layer of the instrument cluster overlay.
The dark outer layer of the overlay prevents the indi-
cator from being clearly visible when it is not illumi-
nated. An amber Light Emitting Diode (LED) behind
the cutout in the opaque layer of the overlay causes
the icon to appear silhouetted against an amber field
through the translucent outer layer of the overlay
when the indicator is illuminated from behind by the
LED, which is soldered onto the instrument cluster
electronic circuit board. The wait-to-start indicator is
serviced as a unit with the instrument cluster.
OPERATION
The wait-to-start indicator gives an indication to
the vehicle operator when the diesel engine glow
plugs are energized in their pre-heat operating mode.
This indicator is controlled by a transistor on the
instrument cluster circuit board based upon cluster
programming and electronic messages received by
the cluster from the Engine Control Module (ECM)
over the Controller Area Network (CAN) data bus.
The wait-to-start indicator Light Emitting Diode
(LED) is completely controlled by the instrument
cluster logic circuit, and that logic will only allow
this indicator to operate when the instrument cluster
detects that the ignition switch is in the On position.
Therefore, the LED will always be off when the igni-
tion switch is in any position except On. The LED
only illuminates when it is provided a path to ground
by the instrument cluster transistor. The instrument
cluster will turn on the wait-to-start indicator for the
following reasons:
²Bulb Test- Each time the ignition switch is
turned to the On position the wait-to-start indicator
is illuminated for about two seconds as a bulb test.
²Wait-To-Start Lamp-On Message- Each time
the cluster receives a wait-to-start lamp-on message
from the ECM indicating that the diesel engine glow
plugs are energized in their pre-heat operating mode,
the wait-to-start indicator will be illuminated. The
indicator remains illuminated until the cluster
receives a wait-to-start lamp-off message indicating
that the pre-heat mode of the glow plugs has been
completed, until the ECM detects that the engine is
running, or until the ignition switch is turned to the
Off position, whichever occurs first.
8J - 28 INSTRUMENT CLUSTERVA