2006 MERCEDES-BENZ SPRINTER relay

CHIME / BUZZER
TABLE OF CONTENTS
page page
CHIME/BUZZER
DESCRIPTION..........................1
OPERATION............................1DIAGNOSIS AND TESTING - CHIME
WARNING SYSTEM.....................2
CHIME / BUZZER
DESCRIPTION
A chime warning system is standard factory-in-
stalled equipment. The chime warning system uses a
chime tone generator and a contactless relay that are
soldered onto the electronic circuit board inside the
ElectroMechanical Instrument Cluster (EMIC) to
provide audible indications of various vehicle condi-
tions that may require the attention of the vehicle
operator or occupants. The microprocessor-based
EMIC utilizes electronic messages received from
other modules in the vehicle over the Controller Area
Network (CAN) data bus network along with hard
wired inputs to the cluster to monitor many sensors
and switches throughout the vehicle. In response to
those inputs, the circuitry and internal programming
of the EMIC allow it to control audible outputs that
are produced through its on-board chime tone gener-
ator and contactless relay.
The EMIC circuitry and its chime tone generator
are capable of producing the following audible out-
puts:
²Single Chime Tone- A single, extended ªbeep-
likeº chime tone is issued as a seat belt reminder.
²Fast Rate Repetitive Chime Tone- Repeated
ªbeep-likeº tones that are issued at a fast rate as an
audible alert and to support various visual warnings.
²Slow Rate Repetitive Click Tone- Repeated
ªclick-likeº tones that are issued at a slow rate to
emulate turn signal and hazard flasher operation.
²Fast Rate Repetitive Click Tone- Repeated
ªclick-likeº tones that are issued at a fast rate to
emulate turn signal flasher operation with a bulb
out.
Hard wired circuitry connects the EMIC and the
various chime warning switch and sensor inputs to
their respective modules and to each other through
the electrical system of the vehicle. These hard wired
circuits are integral to the vehicle wire harness,
which is routed throughout the vehicle and retained
by many different methods. These circuits may be
connected to each other, to the vehicle electrical sys-
tem and to the EMIC through the use of a combina-
tion of soldered splices, splice block connectors, andmany different types of wire harness terminal con-
nectors and insulators. Refer to the appropriate wir-
ing information. The wiring information includes
wiring diagrams, proper wire and connector repair
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 chime tone generator and contactless
relay cannot be adjusted or repaired. If the chime
tone generator or contactless relay are damaged or
faulty, the entire EMIC unit must be replaced.
OPERATION
The chime warning system components operate on
battery current received through a non-switched
fused B(+) circuit so that the system may operate
regardless of the ignition switch position. The Elec-
troMechanical Instrument Cluster (EMIC) also mon-
itors the ignition switch position so that some chime
features will only occur with ignition switch in the
On position, while others occur regardless of the igni-
tion switch position.
The chime warning system provides an audible
indication to the vehicle operator or occupants under
the following conditions:
²Engine Oil Level Low Warning- Each time
the ignition switch is turned to the On position, the
EMIC chime tone generator will generate a fast rate
repetitive chime tone if electronic messages are
received over the Controller Area Network (CAN)
data bus from the Engine Control Module (ECM)
indicating that the engine level is too low. The ECM
uses internal programming and hard wired inputs
from the engine oil level and temperature sensor to
determine the engine oil level. This audible warning
occurs in concert with the visual warning provided by
the multi-function indicator in the cluster.
²Fasten Seat Belt Reminder- Each time the
ignition switch is turned to the On position, the
EMIC chime tone generator will generate a single
extended chime tone for a duration of about six sec-
onds, or until the driver side front seat belt is fas-
tened, whichever occurs first. The EMIC uses
internal programming and a hard wired input from
the driver side front seat belt switch to determine
VACHIME/BUZZER 8B - 1

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

ELECTRONIC CONTROL MODULES
TABLE OF CONTENTS
page page
CENTRAL TIMER MODULE
DESCRIPTION..........................1
OPERATION............................1
DIAGNOSIS AND TESTING - CENTRAL TIMER
MODULE.............................2
REMOVAL.............................2
INSTALLATION..........................3
CONTROLLER ANTILOCK BRAKE
DESCRIPTION..........................3
REMOVAL.............................3INSTALLATION..........................3
ENGINE CONTROL MODULE
DESCRIPTION..........................3
REMOVAL.............................6
INSTALLATION..........................6
TRANSMISSION CONTROL MODULE
DESCRIPTION..........................6
OPERATION............................7
STANDARD PROCEDURE - TCM ADAPTATION . 10
CENTRAL TIMER MODULE
DESCRIPTION
The central timer module (CTM) is located beneath
the driver seat. The CTM uses information carried on
the programmable communications interface (PCI)
data bus network along with many hard wired inputs
to monitor many sensor and switch inputs. In
response to those inputs, the circuitry and program-
ming of the CTM allow it to supply the vehicle occu-
pants with audible and visual information, and to
control and integrate many functions and features of
the vehicle through both hard wired outputs and the
transmission of message outputs to other modules in
the vehicle over the PCI data bus.
The features that the CTM supports or controls
include the following:
²Central Locking- The CTM on vehicles
equipped with the optional Vehicle Theft Security
System (VTSS) includes a central locking/unlocking
feature.
²Enhanced Accident Response- The CTM pro-
vides an optional enhanced accident response fea-
ture. This is a programmable feature.
²Panic Mode- The CTM provides support for
the optional RKE system panic mode including horn,
headlamp, and park lamp flash features.
²Power Lock Control- The CTM provides the
optional power lock system features, including sup-
port for the automatic door lock and door lock inhibit
modes.
²Programmable Features- The CTM provides
support for certain programmable features.
²Remote Keyless Entry- The CTM provides
the optional Remote Keyless Entry (RKE) system fea-
tures, including support for the RKE Lock (with
optional horn and park lamps flash), Unlock (with
park lamps flash, driver-door-only unlock, andunlock-all-doors), Panic, and illuminated entry
modes, as well as the ability to be programmed to
recognize up to four RKE transmitters. The RKE
horn, driver-door-only unlock, and unlock-all-doors
features are programmable.
²Vehicle Theft Security System- The CTM
provides control of the optional Vehicle Theft Secu-
rity System (VTSS) features, including support for
the central locking/unlocking mode and control of the
Security indicator in the instrument cluster.
Hard wired circuitry connects the CTM to the elec-
trical system of the vehicle. Refer to the appropriate
wiring information.
Many of the features in the vehicle controlled or
supported by the CTM are programmable using the
DRBIIItscan tool. However, if any of the CTM hard-
ware components are damaged or faulty, the entire
CTM unit must be replaced. The hard wired inputs
or outputs of all CTM versions can be diagnosed
using conventional diagnostic tools and methods;
however, for diagnosis of the CTM or the PCI data
bus, the use of a DRBIIItscan tool is required. Refer
to the appropriate diagnostic information.
OPERATION
The central timer module (CTM) monitors many
hard wired switch and sensor inputs as well as those
resources it shares with other modules in the vehicle
through its communication over the programmable
communications interface (PCI) data bus network.
The internal programming and all of these inputs
allow the CTM to determine the tasks it needs to
perform and their priorities, as well as both the stan-
dard and optional features that it should provide.
The CTM then performs those tasks and provides
those features through both PCI data bus communi-
cation with other modules and hard wired outputs
through a number of driver circuits, relays, and
VAELECTRONIC CONTROL MODULES 8E - 1

actuators.These outputs allow the CTM the ability to
control numerous accessory systems in the vehicle.
The CTM monitors its own internal circuitry as
well as many of its input and output circuits, and
will store a Diagnostic Trouble Code (DTC) in elec-
tronic memory for any failure it detects. These DTCs
can be retrieved and diagnosed using a DRBIIItscan
tool. Refer to the appropriate diagnostic information.
HARD WIRED INPUTS
The hard wired inputs to the CTM include the fol-
lowing:
²Fused B(+)
²Fused ignition switch output (run-acc)
²Fused ignition switch output (run-start)
²Ground
²Key-in ignition switch sense
²Sliding door switch sense
²Passenger door switch sense
²Driver door switch sense
²PCI bus circuit
HARD WIRED OUTPUTS
The hard wired outputs of the CTM include the fol-
lowing:
²Door lock relay output
²Door unlock relay output
²VTSS indicator driver
MESSAGING
The CTM uses the following messages received
from other electronic modules over the PCI data bus:
²Airbag Deploy (ACM)
²Beep request (CMTC)
²Charging System Failure (PCM)
²Chime request (EMIC)
²Engine RPM (PCM)
²OK to Arm VTSS (PCM)
²Security indicator request (SKIM)
²System Voltage (PCM)
²Valid/Invalid Key (SKIM)
²Vehicle Distance (PCM)
²Vehicle Speed (PCM)
DIAGNOSIS AND TESTING - CENTRAL TIMER
MODULE
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 inputs to and outputs from the
central timer module (CTM) may be diagnosed and
tested using conventional diagnostic tools and meth-
ods. Refer to the appropriate wiring information.
However, conventional diagnostic methods may not
prove conclusive in the diagnosis of the CTM. In
order to obtain conclusive testing of the CTM, the
programmable communications interface (PCI) data
bus network and all of the modules that provide
inputs to or receive outputs from the CTM must also
be checked. The most reliable, efficient, and accurate
means to diagnose the CTM, the PCI data bus net-
work, and the modules that provide inputs to, or
receive outputs from, the CTM requires the use of a
DRBIIItscan tool. Refer to the appropriate diagnos-
tic information.
REMOVAL
(1) Disconnect and isolate the battery negative
cable.
(2) Slide the driver seat to the full forward posi-
tion.
(3) Disconnect the wire harness connector for the
seat belt latch. (Fig. 1).
(4) Remove the screws that secure the closeout
panel beneathe the driver seat cushion and remove
the panel.
(5) Remove the screws that secure the central
timer module to the bracket.
(6) Disconnect the wire harness connectors from
the central timer module.
(7) Remove the central timer module from the
vehicle.
8E - 2 ELECTRONIC CONTROL MODULESVA

INSTALLATION
(1) Position the central timer module in the vehicle
(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 milliliter
board assembly fitted on both sides. The routing of
the wiring harness connector at the ECM connector
are split into interfering cables and sensitive cables
in order to achieve improved electromagnetic compat-
ibility. The smaller wiring harness connector is used
for the vehicle wiring harness and the larger harness
is used for the engine wiring harness. 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. 3).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

New software has been loaded to the ECM for EGR
control. This is due to the wider operating range and
larger volume of recirculated gas. There is a consid-
erable number of new, adapted, and optimized func-
tions, particularly with regard to injection, EGR,
boost control, sensing of the input parameters and
the signaling of the actuators (Fig. 3).
²The rail pressure control achieved by signaling
the quantity control valve in the high pressure pump
and the pressure regulator results in reduced power
consumption of high pressure pump and in lowering
fuel pressures
²Individual cylinder torque control for smooth
engine running: using the crankshaft position sensor
signals, the ECM detect non-uniform engine running
results from uneven torque contributions of the indi-
vidual cylinders and adjust the injection quantities of
the individual injectors so that all cylinders make the
same torque contribution
²A relay is used for activating the electric in-tank
fuel pump
²Heated crankcase ventilation to ensure pressure
compensation even at low temperatures
²Improved boost pressure control using an elec-
tric variable nozzle turbine actuator with position
feed back
²Controlled fuel heating using the high pressure
pump closed-loop control
²Translation of the drive input received from the
accelerator pedal module which is equipped with
dual hall sensors²Measurement of the intake air mass using new
mass air flow (MAF) sensor with increase precision
and extended measuring range
²O2 sensor for measuring the amount of oxygen
in the exhaust in order to calculate the air to fuel
ratio. With the intake air mass being known, the
injected fuel quantity can be calculated from the air
to fuel ratio
²Activation of the O2 sensor heater to burn off
deposits
²Full load EGR with a more precise, model based
EGR closed-loop control. The ECM calculates the
EGR rate from the various sensor signals. Using the
calculate EGR rate in percent instead of the fresh air
mass flow as a control parameter enables a more pre-
cise control of the EGR rate as well as better correc-
tion of the target value.
The oxygen sensor signal can be used in combina-
tion with the mass air flow signal, the injection
quantity signal and pressure and temperature sig-
nals to perform the following functions for optimized
closed loop control and monitoring of emissions
related components:
²Injection valve quantity drift compensation in
partial load range: the oxygen content in the exhaust
is calculated from the air mass and from injection
quantity signal and is compared to the air-fuel ratio
as measured by the sensor. If the calculated air-fuel
ratio differs from the measured air-fuel ratio, the is
no correction of the injection quantity but the EGR
Fig. 3 ECM CONTROL
VAELECTRONIC CONTROL MODULES 8E - 5

²Position of selector lever.
²Selected shift range.
²CAN signals.
²Engine Status.
Engine speed limits may be reached in all gears
with full throttle or in kick-down operation. In for-
ward driving, the shift range of the forward gears
can be adjusted by the operator by tipping the selec-
tor lever to the left or right (AutoStick). However, the
TCM features a downshift inhibitor to prevent the
engine from overspeeding.
OPERATION
The transmission control module (TCM) deter-
mines the current operating conditions of the vehicle
and controls the shifting process for shift comfort and
driving situations. It receives this operating data
from sensors and broadcast messages from other
modules.
The TCM uses inputs from several sensors that are
directly hardwired to the controller and it uses sev-
eral indirect inputs that are used to control shifts.
This information is used to actuate the proper sole-
noids in the valve body to achieve the desired gear.
The shift lever assembly (SLA) has several items
that are monitored by the TCM to calculate shift
lever position. The reverse light switch, an integral
part of the SLA, controls the reverse light relay con-
trol circuit. The Brake/Transmission Shift Interlock
(BTSI) solenoid and the park lockout solenoid (also
part of the SLA) are controlled by the TCM.
The ECM and ABS broadcast messages over the
controller area network (CAN C) bus for use by the
TCM. The TCM uses this information, with other
inputs, to determine the transmission operating con-
ditions.
The TCM:
²determines the momentary operating conditions
of the vehicle.
²controls all shift processes.
²considers shift comfort and the driving situation.
The TCM controls the solenoid valves for modulat-
ing shift pressures and gear changes. Relative to the
torque being transmitted, the required pressures are
calculated from load conditions, engine rpm, vehicle
speed, and ATF temperature.
The following functions are contained in the TCM:
²Shift Program
²Downshift Safety
²Torque Converter Lock-Up Clutch.
²Adaptation.
This transmission does not have a TCM relay.
Power is supplied to the SLA and the TCM directly
from the ignition.
The TCM continuously checks for electrical prob-
lems, mechanical problems, and some hydraulic prob-
lems. When a problem is sensed, the TCM stores a
diagnostic trouble code (DTC). Some of these codescause the transmission to go into ªLimp-Inº or
ªdefaultº mode. Some DTCs cause permanent
Limp-In and others cause temporary Limp-In. The
NAG1 defaults in the current gear position if a DTC
is detected, then after a key cycle the transmission
will go into Limp-in, which is mechanical 2nd gear.
Some DTCs may allow the transmission to resume
normal operation (recover) if the detected problem
goes away. A permanent Limp-In DTC will recover
when the key is cycled, but if the same DTC is
detected for three key cycles the system will not
recover and the DTC must be cleared from the TCM
with the DRBIIItscan tool.
TCM SIGNALS
The TCM registers one part of the input signals by
direct inputs, the other part by CAN C bus. In addi-
tion to the direct control of the actuators, the TCM
sends various output signals by CAN C bus to other
control modules.
Selector Lever Position
The TCM monitors the SLA for all shift lever posi-
tions via the CAN bus.
ATF Temperature Sensor
The ATF temperature sensor is a positive temper-
ature co-efficient (PTC) thermistor. It measures the
temperature of the transmission fluid and is a direct
input signal for the TCM. The temperature of the
ATF has an influence on the shifttime and resulting
shift quality. As the temperature rises, resistance
rises, and therefore, the probing voltage is decreas-
ing. Because of its registration, the shifting process
can be optimized in all temperature ranges.
The ATF temperature sensor is wired in series
with the park/neutral contact. The temperature sig-
nal is transmitted to the TCM only when the reed
contact of the park/neutral contact is closed because
the TCM only reads ATF temperature while in any
forward gear, or REVERSE. When the transmission
is in PARK or NEUTRAL, the TCM will substitute
the engine temperature for the ATF temperature.
Starter Interlock
The TCM monitors a contact switch wired in series
with the transmission temperature sensor to deter-
mine PARK and NEUTRAL positions. The contact
switch is open in PARK and NEUTRAL. The TCM
senses transmission temperature as high (switch
supply voltage), confirming switch status as open.
The TCM then broadcasts a message over CAN bus
to confirm switch status. The PCM receives this
information and allows operation of the starter cir-
cuit.
VAELECTRONIC CONTROL MODULES 8E - 7

STARTING SYSTEM
TABLE OF CONTENTS
page page
STARTING SYSTEM
DESCRIPTION.........................28
OPERATION...........................28
DIAGNOSIS AND TESTING - STARTING
SYSTEM............................29
SPECIFICATIONS
TORQUE - STARTER - DIESEL...........33
SPECIFICATIONS - STARTER MOTOR -
DIESEL.............................33STARTER MOTOR
DIAGNOSIS AND TESTING - STARTER
MOTOR .............................33
REMOVAL.............................34
INSTALLATION.........................35
STARTER MOTOR RELAY
DESCRIPTION.........................35
REMOVAL.............................35
INSTALLATION.........................36
STARTING SYSTEM
DESCRIPTION
The starting system consists of:
²Starter relay
²Starter motor (including an integral starter sole-
noid)
Other components to be considered as part of start-
ing system are:
²Battery
²Battery cables
²Ignition switch and key lock cylinder
²Park/neutral position switch (automatic trans-
mission)
²Wire harnesses and connections.
The Battery, Starting, and Charging systems oper-
ate in conjunction with one another, and must be
tested as a complete system. For correct operation of
starting/charging systems, all components used in
these 3 systems must perform within specifications.
When attempting to diagnose any of these systems, it
is important that you keep their interdependency in
mind.
The diagnostic procedures used in each of these
groups include the most basic conventional diagnostic
methods, to the more sophisticated On-Board Diag-
nostics (OBD) built into the Engine Control Module
(ECM). Use of an induction-type milliampere amme-
ter, volt/ohmmeter, battery charger, carbon pile rheo-
stat (load tester), and 12-volt test lamp may be
required.
Certain starting system components are monitored
by the ECM and may produce a Diagnostic Trouble
Code (DTC).
OPERATION
The starting system components form two separate
circuits. A high-amperage feed circuit that feeds the
starter motor high-amperage, and a low-amperagecontrol circuit that operates on less than 20 amperes.
The high-amperage feed circuit components include
the battery, the battery cables, the contact disc por-
tion of the starter solenoid, and the starter motor
itself. The low-amperage control circuit components
include the ignition switch, the park/neutral position
switch (automatic transmission), the starter relay,
the electromagnetic windings of the starter solenoid,
and the connecting wire harness components.
If the vehicle is equipped with an automatic trans-
mission, battery voltage is supplied through the low-
amperage control circuit to the coil battery terminal
of the starter relay when the ignition switch is
turned to the momentary Start position. The park/
neutral position switch is installed in series between
the starter relay coil ground terminal and ground.
This normally open switch prevents the starter relay
from being energized and the starter motor from
operating unless the automatic transmission gear
selector is in the Neutral or Park positions.
When the starter relay coil is energized, the nor-
mally open relay contacts close. The relay contacts
connect the relay common feed terminal to the relay
normally open terminal. The closed relay contacts
energize the starter solenoid coil windings.
The energized solenoid pull-in coil pulls in the sole-
noid plunger. The solenoid plunger pulls the shift
lever in the starter motor. This engages the starter
overrunning clutch and pinion gear with the starter
ring gear on the manual transmission flywheel or on
the automatic transmission torque converter or
torque converter drive plate.
As the solenoid plunger reaches the end of its
travel, the solenoid contact disc completes the high-
amperage starter feed circuit and energizes the sole-
noid plunger hold-in coil. Current now flows between
the solenoid battery terminal and the starter motor,
energizing the starter.
Once the engine starts, the overrunning clutch pro-
tects the starter motor from damage by allowing the
8F - 28 STARTING SYSTEMVA