2006 MERCEDES-BENZ SPRINTER glove box

INSTRUMENT PANEL
ANTENNA CABLE
REMOVAL
(1) Disconnect and isolate the battery negative
cable.
(2) Remove the A-pillar trim (Refer to 23 - BODY/
INTERIOR/A-PILLAR TRIM - REMOVAL).
(3) Remove the portion of the headliner over the
front seat passengers (Refer to 23 - BODY/INTERI-
OR/HEADLINER - REMOVAL).
(4) Disconnect the antenna and electrical connec-
tions near the windshield.
(5) Remove the glove box (Refer to 23 - BODY/IN-
STRUMENT PANEL/GLOVE BOX - REMOVAL).
(6) Remove the radio (Refer to 8 - ELECTRICAL/
AUDIO/RADIO - REMOVAL).
(7) Cut both ends of existing cable close to the
instrument panel (Fig. 2).
INSTALLATION
(1) Insert new cable through glove box opening to
the radio opening in the instrument panel.
(2) Route cable up the A-pillar and connect to the
antenna body and cable.
(3) Connect the antenna and electrical connections
near the windshield.
(4) Attach antenna cable to instrument panel wire
harness.
(5) Install glove box (Refer to 23 - BODY/INSTRU-
MENT PANEL/GLOVE BOX - INSTALLATION).
(6) Install the headliner (Refer to 23 - BODY/IN-
TERIOR/HEADLINER - INSTALLATION).
(7) Install the A-pillar trim (Refer to 23 - BODY/
INTERIOR/A-PILLAR TRIM - INSTALLATION).
(8) Install the radio (Refer to 8 - ELECTRICAL/
AUDIO/RADIO - INSTALLATION).
(9) Connect the battery negative cable.
RADIO
REMOVAL
(1) Disconnect and isolate the battery negative
cable.
(2) Using special tool 9241 or equivalent, insert
one into each slot on the face of the radio (Fig. 3).
(3) Disconnect wire harness connector and antenna
from radio.
INSTALLATION
(1) Connect wire harness connector and antenna to
radio.
(2) Position radio to instrument panel and push
into place.
(3) Connect battery negative cable.
SPEAKER
REMOVAL
(1) Disconnect and isolate the battery cable.
(2) Remove the A-pillar trim (Refer to 23 - BODY/
INTERIOR/A-PILLAR TRIM - REMOVAL).
(3) Remove speaker grill (Fig. 4).
Fig. 2 INSTRUMENT PANEL ANTENNA CABLE
Fig. 3 RADIO
1 - SPECIAL TOOL 9241
2 - RADIO
3 - RETAINING TAB
8A - 2 AUDIO/VIDEOVA

the status of the driver side front seat belt. This
audible warning occurs independent of the visual
warning provided by the EMIC ªSeatbeltº indicator.
²Lights-On Warning- The EMIC chime tone
generator will generate repetitive chime tones at a
fast rate when either front door is opened with the
ignition switch in any position except On, and the
exterior lights are turned On. The EMIC uses inter-
nal programming and hard wired inputs from the left
(lighting) control stalk of the multi-function switch,
the ignition switch, and both front door jamb
switches to determine the current status of these
switches. This chime will continue to sound until the
exterior lighting is turned Off, until the ignition
switch is turned to the On position, or until both
front doors are closed, whichever occurs first.
²Key-In-Ignition Warning- The EMIC chime
tone generator will generate repetitive chime tones at
a fast rate when the key is in the ignition lock cylin-
der, the ignition switch is in any position except On,
and either front door is opened. The EMIC uses
internal programming and hard wired inputs from
the key-in ignition switch, the ignition switch, and
both front door jamb switches to determine the cur-
rent status of these switches. The chime will con-
tinue to sound until the key is removed from the
ignition lock cylinder, until the ignition switch is
turned to the On position, or until both front doors
are closed, whichever occurs first.
²Audible Turn Signal/Hazard Warning Sup-
port- The EMIC contactless relay will generate
repetitive clicks at a slow rate during normal turn
signal/hazard warning operation, or at a fast rate
when a turn signal lamp bulb or circuit is inopera-
tive, in concert with the operation of the turn signal
indicators in the cluster. These clicks are designed to
emulate the sound of the opening and closing of the
contact points in a conventional electromechanical
turn signal or hazard warning flasher. The EMIC
uses a hard wired input received from the turn sig-
nal relay in the fuse block beneath the steering col-
umn through the turn signal or hazard warning
switch circuitry of the multi-function switch to deter-
mine when to flash the turn signal indicators and
activate the contactless relay on the cluster electronic
circuit board. The turn signal clicks will continue to
sound until the turn signal switch is turned Off, or
until the ignition switch is turned to the Off position,
whichever occurs first. The hazard warning clicks
will continue to sound until the hazard warning
switch is turned Off.
The EMIC provides chime service for all available
features in the chime warning system. The EMIC relies
upon its internal programming and hard wired inputs
from the front door ajar switches, the key-in ignition
switch, the ignition switch, the seat belt switch, and the
turn signal/hazard warning (multi-function) switches.
The EMIC relies upon electronic message inputsreceived from other electronic modules over the CAN
data bus network to provide chime service for the low
engine oil level warning. Upon receiving the proper
inputs, the EMIC activates the chime tone generator or
the contactless relay to provide the audible warning to
the vehicle operator. The internal programming of the
EMIC determines the priority of each chime request
input that is received, as well as the rate and duration
of each tone that is to be generated. See the owner's
manual in the vehicle glove box for more information on
the features provided by the chime warning system.
The hard wired chime warning system inputs to
the EMIC, as well as other hard wired circuits for
this system may be diagnosed and tested using con-
ventional diagnostic tools and procedures. However,
conventional diagnostic methods may not prove con-
clusive in the diagnosis of the EMIC, the CAN data
bus network, or the electronic message inputs used
by the EMIC to provide chime warning system ser-
vice. The most reliable, efficient, and accurate means
to diagnose the EMIC, the CAN data bus network,
and the electronic message inputs for the chime
warning system requires the use of a diagnostic scan
tool. Refer to the appropriate diagnostic information.
DIAGNOSIS AND TESTING - CHIME WARNING
SYSTEM
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, or instrument panel component diagno-
sis or service. Disconnect and isolate the battery
negative (ground) cable, then wait two minutes for
the system capacitor to discharge before perform-
ing further diagnosis or service. This is the only
sure way to disable the supplemental restraint sys-
tem. Failure to take the proper precautions could
result in accidental airbag deployment.
The hard wired chime warning system inputs to
the ElectroMechanical Instrument Cluster (EMIC),
as well as other hard wired circuits for this system
may be diagnosed and tested using conventional
diagnostic tools and procedures. However, conven-
tional diagnostic methods may not prove conclusive
in the diagnosis of the EMIC, the Controller Area
Network (CAN) data bus network, or the electronic
message inputs used by the EMIC to provide chime
warning system service. The most reliable, efficient,
and accurate means to diagnose the EMIC, the CAN
data bus network, and the electronic message inputs
for the chime warning system requires the use of a
diagnostic scan tool. Refer to the appropriate diag-
nostic information.
8B - 2 CHIME/BUZZERVA

For battery system maintenance schedules and
jump starting procedures, see the owner's manual in
the vehicle glove box. Optionally, refer to the Lubri-
cation and Maintenance section of this manual for
the recommended battery maintenance schedules and
for the proper battery jump starting procedure. While
battery charging can be considered a maintenance
procedure, the battery charging procedure and
related information are located later in this section of
this service manual. This was done because the bat-
tery must be fully-charged before any battery system
diagnosis or testing procedures can be performed.
OPERATION
The battery system is designed to provide a safe,
efficient, reliable and mobile means of delivering and
storing electrical energy. This electrical energy is
required to operate the engine starting system, as
well as to operate many of the other vehicle acces-
sory systems for limited durations while the engine
and/or the charging system are not operating. The
battery system is also designed to provide a reserve
of electrical energy to supplement the charging sys-
tem for short durations while the engine is running
and the electrical current demands of the vehicle
exceed the output of the charging system. In addition
to delivering, and storing electrical energy for the
vehicle, the battery system serves as a capacitor and
voltage stabilizer for the vehicle electrical system. It
absorbs most abnormal or transient voltages caused
by the switching of any of the electrical components
or circuits in the vehicle.
DIAGNOSIS AND TESTING - BATTERY SYSTEM
The battery, starting, and charging systems in the
vehicle operate with one another and must be tested
as a complete system. In order for the engine to start
and the battery to maintain its charge properly, all ofthe components that are used in these systems must
perform within specifications. It is important that
the battery, starting, and charging systems be thor-
oughly tested and inspected any time a battery needs
to be charged or replaced. The cause of abnormal bat-
tery discharge, overcharging or early battery failure
must be diagnosed and corrected before a battery is
replaced and before a vehicle is returned to service.
The service information for these systems has been
separated within this service manual to make it eas-
ier to locate the specific information you are seeking.
However, when attempting to diagnose any of these
systems, it is important that you keep their interde-
pendency in mind.
The diagnostic procedures used for the battery,
starting, and charging systems include the most
basic conventional diagnostic methods, to the more
sophisticated On-Board Diagnostics (OBD) built into
the Powertrain Control Module (PCM). Use of an
induction-type milliampere ammeter, a volt/ohmme-
ter, a battery charger, a carbon pile rheostat (load
tester) and a 12-volt test lamp may be required. All
OBD-sensed systems are monitored by the PCM.
Each monitored circuit is assigned a Diagnostic Trou-
ble Code (DTC). The PCM will store a DTC in elec-
tronic memory for any failure it detects. Refer to
Charging System for the proper charging system on-
board diagnostic test procedures.
MICRO 420 BATTERY TESTER
The Micro 420 automotive battery tester is
designed to help the dealership technicians diagnose
the cause of a defective battery. Follow the instruc-
tion manual supplied with the tester to properly
diagnose a vehicle. If the instruction manual is not
available refer to the standard procedure in this sec-
tion, which includes the directions for using the
Micro 420 battery tester.
8F - 2 BATTERY SYSTEMVA

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

remains illuminated until the cluster receives a
lamp-off message from the ECM, or until the ignition
switch is turned to the Off position, whichever occurs
first.
The ECM continually monitors the constant engine
speed (ADR) switch and electronic messages from the
Controller Antilock Brake (CAB) concerning the sta-
tus of the four wheel speed sensors, the park brake
switch and the brake lamp switch to determine the
correct operating mode for the ADR feature. The
ECM then sends the proper lamp-on or lamp-off mes-
sages to the instrument cluster. See the owner's man-
ual in the vehicle glove box for more information on
the features, use, activation and deactivation of the
constant engine speed (ADR) feature. For proper
diagnosis of the ADR feature, the ECM, the CAB, the
CAN data bus, or the electronic message inputs to
the instrument cluster that control the ADR indica-
tor, a diagnostic scan tool is required. Refer to the
appropriate diagnostic information.
AIRBAG INDICATOR
DESCRIPTION
An airbag indicator is standard equipment on all
instrument clusters. The airbag indicator is located
near the left edge of the instrument cluster, next to
the tachometer. The airbag indicator consists of a
stencil-like cutout of the letters ªSRSº 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. A red
Light Emitting Diode (LED) behind the cutout in the
opaque layer of the overlay causes the ªSRSº text to
appear in red 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 air-
bag indicator is serviced as a unit with the instru-
ment cluster.
OPERATION
The airbag (SRS) indicator gives an indication to
the vehicle operator when the Airbag Control Module
(ACM) has recorded a Diagnostic Trouble Code (DTC)
for a Supplemental Restraint System (SRS) circuit or
component malfunction. Such a DTC may indicate
that the SRS is faulty or inoperative. The airbag
indicator is controlled by a transistor on the instru-
ment cluster circuit board based upon cluster pro-
gramming and a hard wired input received by the
cluster from the ACM. The airbag 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 offwhen 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 airbag indi-
cator for the following reasons:
²Bulb Test- Each time the ignition switch is
turned to the On position the airbag indicator is illu-
minated for about four seconds. The entire four sec-
ond bulb test is a function of the ACM.
²Airbag Lamp-On Input- Each time the cluster
receives a lamp-on input from the ACM, the airbag
indicator will be illuminated. The indicator can be
flashed on and off, or illuminated solid, as dictated
by the ACM input. For some DTC's, if the problem
does not recur, the ACM will send a lamp-off input
automatically. Other DTC's may require that a fault
be repaired and the ACM be reset before a lamp-off
input will be sent. For more information on the ACM
and the DTC set and reset parameters, refer to 8 -
ELECTRICAL/RESTRAINTS/AIRBAG CONTROL
MODULE - OPERATION). The indicator remains
illuminated until the cluster receives a lamp-off
input from the ACM, or until the ignition switch is
turned to the Off position, whichever occurs first.
²Airbag Indicator Malfunction- Following the
seatbelt reminder function, each time the cluster
detects a malfunction in the airbag (SRS) indicator or
the airbag indicator circuit, the cluster will flash the
seatbelt indicator on and off. The cluster will con-
tinue to flash the seatbelt indicator until the airbag
indicator circuit fault is resolved, or until the ignition
switch is turned to the Off position, whichever occurs
first.
The ACM continually monitors the SRS circuits
and sensors to decide whether the system is in good
operating condition. The ACM then provides the
proper lamp-on or lamp-off inputs to the instrument
cluster. If the ACM provides a lamp-on input after
the bulb test, it indicates that the ACM has detected
a system malfunction and/or that the airbags and
seat belt tensioners may not deploy when required,
or may deploy when not required. The ACM will
store a DTC for any malfunction it detects. The ACM
input circuit to the instrument cluster can be diag-
nosed using conventional diagnostic tools and meth-
ods. For proper diagnosis of the SRS, the ACM, or
the instrument cluster circuitry that controls the air-
bag indicator, a diagnostic scan tool is required. Refer
to the appropriate diagnostic information.
AMBIENT TEMPERATURE
INDICATOR
DESCRIPTION
An ambient temperature indicator is optional
equipment on all instrument clusters. In vehicles so
VAINSTRUMENT CLUSTER 8J - 11

clock remains functional regardless of the ignition
switch position.
The vehicle operator can choose to have the
optional ambient temperature indicator displayed
instead of the clock information, but the clock and
ambient temperature indicator cannot be displayed
at the same time. The clock or ambient temperature
indicator display option is selected using the multi-
function indicator clock switch on the instrument
cluster circuit board. This switch is actuated manu-
ally by depressing the clock switch push button that
extends through the lower edge of the cluster lens
below the left end of the multi-function indicator.
Actuating this switch momentarily will toggle the
display between the clock and ambient temperature
indicator modes. Actuating this switch twice within
about one second will cause the display to toggle, but
then automatically revert to the originally selected
mode after about twenty seconds.
See the owner's manual in the vehicle glove box for
more information on the features, use, operation and
setting procedures for the clock. For proper testing of
the instrument cluster circuitry that controls the
clock functions, a diagnostic scan tool is required.
Refer to the appropriate diagnostic information.
COOLANT LOW INDICATOR
DESCRIPTION
A coolant low indicator is standard equipment on
all instrument clusters. The coolant low indicator is
located near the lower edge of the instrument cluster,
to the left of the multi-function indicator display. The
coolant low indicator consists of the International
Control and Display Symbol icon for ªLow Engine
Coolantº 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. A red Light Emitting Diode (LED) behind the
cutout in the opaque layer of the overlay causes the
icon to appear silhouetted against a red 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 coolant low indicator is ser-
viced as a unit with the instrument cluster.
OPERATION
The coolant low indicator gives an indication to the
vehicle operator when the engine coolant level is low.
This indicator is controlled by a transistor on the
instrument cluster circuit board based upon cluster
programming and a hard wired input received by the
cluster from the engine coolant level switch. The cool-
ant low indicator Light Emitting Diode (LED) is com-
pletely controlled by the instrument cluster logiccircuit, 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 ignition switch is in
any position except On. The LED only illuminates
when it is provided a path to ground by the instru-
ment cluster transistor. The instrument cluster will
turn on the coolant low indicator for the following
reasons:
²Bulb Test- Each time the ignition switch is
turned to the On position the coolant low indicator is
illuminated for about two seconds as a bulb test.
²Engine Coolant Level Switch Input- Each
time the cluster detects an appropriate input on the
low coolant fluid level sense circuit (engine coolant
level switch resistance low = engine coolant level low)
while the ignition switch is in the On position, the
coolant low indicator will be illuminated. The indica-
tor remains illuminated until the low coolant fluid
level sense input to the cluster changes (engine cool-
ant level switch resistance high = engine coolant
level full), or until the ignition switch is turned to
the Off position, whichever occurs first. The engine
coolant level switch also features a diagnostic resis-
tor connected in parallel between the switch input
and output to provide the cluster with verification
that the low coolant fluid level sense circuit is not
open or shorted.
The engine coolant level switch integral to the cool-
ant bottle provides a hard wired input to the instru-
ment cluster circuitry through the low coolant fluid
level sense circuit. The engine coolant level switch
and the low coolant fluid level sense circuit to the
instrument cluster can be diagnosed using conven-
tional diagnostic tools and methods. For proper diag-
nosis of the instrument cluster circuitry that controls
the coolant low indicator, a diagnostic scan tool is
required. Refer to the appropriate diagnostic infor-
mation.
ENGINE TEMPERATURE
GAUGE
DESCRIPTION
An engine coolant temperature gauge is standard
equipment on all instrument clusters. The engine
coolant temperature gauge is located in the upper
right corner of the instrument cluster, to the right of
the speedometer. The engine coolant temperature
gauge consists of a movable gauge needle or pointer
controlled by the instrument cluster circuitry and a
fixed 45 degree scale on the cluster overlay that
reads left-to-right from 120É C to 40É C for Canadian
vehicles, or from 250É F to 110É F for United States
vehicles. An International Control and Display Sym-
bol icon for ªEngine Coolant Temperatureº is located
VAINSTRUMENT CLUSTER 8J - 15

through the fuel level sense circuit. The fuel level
sensor is a potentiometer that changes resistance
according to the fuel level. As the fuel level
decreases, the resistance through the fuel level sen-
sor increases. The instrument cluster applies a fuel
tank characteristic curve and fuel tank reserve valve
setting to the fuel level sensor input, which must be
configured when the cluster is initialized. These
characteristics determine the algorithm the cluster
uses to display the fuel level data on the fuel gauge
and the control for the low fuel warning indicator.
The fuel level sensor and the fuel level sense circuit
to the instrument cluster can be diagnosed using con-
ventional diagnostic tools and methods. For proper
diagnosis of the instrument cluster circuitry that con-
trols the fuel gauge, a diagnostic scan tool is
required. Refer to the appropriate diagnostic infor-
mation.
LOW OIL LEVEL INDICATOR
DESCRIPTION
A low oil level indicator is standard equipment on
all instrument clusters. The low oil level indicator is
located near the lower edge of the instrument cluster,
to the left of the multi-function indicator display. The
low oil level indicator consists of the International
Control and Display Symbol icon for ªEngine Oilº
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. A red
Light Emitting Diode (LED) behind the cutout in the
opaque layer of the overlay causes the icon to appear
silhouetted against a red field through the translu-
cent outer layer of the overlay when the indicator is
illuminated from behind by the LED, which is sol-
dered onto the instrument cluster electronic circuit
board. The low oil level indicator is serviced as a unit
with the instrument cluster.
OPERATION
The low oil level indicator gives an indication to
the vehicle operator when the engine oil level is low.
This indicator is controlled by a transistor on the
instrument cluster electronic circuit board based
upon cluster programming and electronic messages
received by the cluster from the Engine Control Mod-
ule (ECM) over the Controller Area Network (CAN)
data bus. The low oil level indicator Light Emitting
Diode (LED) is completely controlled by the instru-
ment 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 ignition switch is in any position except On. The
LED only illuminates when it is provided a path toground by the instrument cluster transistor. The
instrument cluster will turn on the low oil level indi-
cator for the following reasons:
²Bulb Test- Each time the ignition switch is
turned to the On position the low oil level indicator
is illuminated for about two seconds as a bulb test.
²Engine Oil Level Low Message- Once the
engine has been started, each time the cluster
receives a message from the ECM indicating that the
engine oil level is at or near the ªMinimumº mark on
the dipstick, the low oil level indicator is illuminated.
The indicator remains illuminated briefly at first, but
will remain illuminated for longer periods as subse-
quent messages indicate that the oil level has
dropped further. Eventually, the indicator will
remain illuminated solid until the engine oil level is
corrected, or until the ignition switch is turned to the
Off position, whichever occurs first.
The instrument cluster also supplements the oil
level indicator by displaying an engine oil icon along
with alpha-numeric messages in the multi-function
indicator Liquid Crystal Display (LCD) advising the
vehicle operator how much oil is required to correct
the engine oil level, and when the ªMaximumº engine
oil level has been exceeded. See the owner's manual
in the vehicle glove box for more information on this
feature.
The ECM continually monitors the engine oil level
and temperature sensor to determine the engine oil
level. The ECM then sends the proper engine oil
level messages to the instrument cluster. If the
instrument cluster turns on the indicator after the
bulb test, even after the engine oil level is sufficient,
it may indicate that the engine or the engine oiling
system requires service. For proper diagnosis of the
engine oil level and temperature sensor, the ECM,
the CAN data bus, or the electronic message inputs
to the instrument cluster that control the low oil
level indicator, a diagnostic scan tool is required.
Refer to the appropriate diagnostic information.
MAINTENANCE INDICATOR
DESCRIPTION
An Active Service SYSTem (ASSYST) engine oil
maintenance indicator is optional equipment on all
instrument clusters. In vehicles so equipped, a sec-
ond, dedicated ASSYST microprocessor is integral to
the cluster electronic circuit board. The ASSYST indi-
cations are displayed and can be toggled with the
clock indication on the right side of the multi-func-
tion indicator Liquid Crystal Display (LCD) located
near the lower edge of the instrument cluster,
directly below the speedometer. The ASSYST displays
include numeric values combined with several icons
to indicate actual engine oil level, and reminders in
time (days) or distance (miles or kilometers) until the
8J - 20 INSTRUMENT CLUSTERVA

next required engine oil maintenance is anticipated.
ASSYST also provides several audible indications
using the electronic tone generator on the instrument
cluster circuit board to supplement these visual dis-
plays.
The indications of the ASSYST engine oil mainte-
nance indicator are not visible when the LCD is not
illuminated. When illuminated, the ASSYST indica-
tions appear as dark characters and icons silhouetted
against an amber field. When the exterior lighting is
turned Off, the display is illuminated at maximum
brightness. When the exterior lighting is turned On,
the display illumination level can be adjusted in con-
cert with the cluster general illumination lighting
using the ª+º (plus) and ª2º (minus) multi-function
indicator push buttons. The ASSYST engine oil main-
tenance indicator is serviced as a unit with the
instrument cluster.
OPERATION
The ASSYST engine oil maintenance indicator
microprocessor uses numerous criteria besides time
and mileage to evaluate vehicle maintenance require-
ments. Time data is taken from the electronic digital
clock integral to the instrument cluster. Vehicle dis-
tance data is obtained from the Controller Antilock
Brake (CAB) over the Controller Area Network
(CAN) data bus. Coolant temperature, engine oil
temperature, engine oil level, engine oil quality,
engine speed, and engine load data are obtained from
the Engine Control Module (ECM) over the CAN
data bus. Using all of the available data and internal
programming, the ASSYST microprocessor then cal-
culates the estimated time and distance to the next
required engine oil maintenance interval. The
ASSYST uses the multi-function indicator LCD to
display that data and, when necessary, issues audible
alerts to the vehicle operator through the electronic
tone generator on the cluster circuit board.
See the owner's manual in the vehicle glove box for
more information on the features, use, operation and
resetting procedures for the ASSYST maintenance
computer. Proper diagnosis and testing of the
ASSYST engine oil maintenance computer, the CAN
data bus and the electronic data bus message inputs
to the EMIC that are used by the ASSYST computer
for its calculations requires the use of a diagnostic
scan tool. Refer to the appropriate diagnostic infor-
mation.
MALFUNCTION INDICATOR
LAMP (MIL)
DESCRIPTION
A Malfunction Indicator Lamp (MIL) is standard
equipment on all instrument clusters. The MIL islocated near the lower edge of the instrument cluster,
to the right of the multi-function indicator display.
The MIL consists of the International Control and
Display Symbol icon for ªEngineº imprinted within a
rectangular cutout in the opaque layer of the instru-
ment cluster overlay. The dark outer layer of the
overlay prevents the indicator from being clearly vis-
ible 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 trans-
lucent outer layer of the overlay when the indicator
is illuminated from behind by the LED, which is sol-
dered onto the instrument cluster electronic circuit
board. The MIL is serviced as a unit with the instru-
ment cluster.
OPERATION
The Malfunction Indicator Lamp (MIL) gives an
indication to the vehicle operator when the Engine
Control Module (ECM) has recorded a Diagnostic
Trouble Code (DTC) for an On-Board Diagnostics II
(OBDII) emissions-related circuit or component mal-
function. The MIL is controlled by a transistor on the
instrument cluster circuit board based upon cluster
programming and electronic messages received by
the cluster from the ECM over the Controller Area
Network (CAN) data bus. The MIL Light Emitting
Diode (LED) is completely controlled by the instru-
ment 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 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 MIL for the fol-
lowing reasons:
²Bulb Test- Each time the ignition switch is
turned to the On position the MIL is illuminated as a
bulb test. The indicator will remain illuminated until
the engine is started, or until the ignition switch is
turned to the Off position, whichever occurs first.
²MIL Lamp-On Message- Each time the clus-
ter receives a MIL lamp-on message from the ECM,
the indicator will be illuminated. The indicator will
remain illuminated until the detected fault is
repaired, or until the ignition switch is turned to the
Off position, whichever occurs first. For more infor-
mation on the ECM and the DTC set and reset
parameters, (Refer to 25 - EMISSIONS CONTROL -
OPERATION).
²Communication Error- If the cluster receives
no lamp-on or lamp-off message from the ECM, the
MIL is illuminated by the instrument cluster. The
indicator remains controlled and illuminated by the
cluster until a valid lamp-on or lamp-off message is
received from the ECM.
VAINSTRUMENT CLUSTER 8J - 21