²Body Control Module
²Remote Keyless Entry Module
(8) Disconnect one component at time, to see if any
component is at fault. If the high reading is not elim-
inated there is a short circuit in the wiring. Refer to
Group 8W, wiring diagrams.
(9) Remove interior and brake lamp fuses. Install
the fuses. The milliampere reading should be 2-4 mA.
If reading is higher than 4 mA:
(a) Disconnect PCM.
(b) If reading is OK, replace PCM.
(c) If reading does not change there is a short
circuit to the PCM. Refer to Group 8W, Wiring Dia-
grams.
BATTERY LOAD TEST
A fully charged battery must have cranking capac-
ity, to provide the starter motor and ignition system
enough power to start the engine over a broad range
of ambient temperatures. A battery load test will ver-
ify the actual cranking capability of the battery.
WARNING: IF BATTERY SHOWS SIGNS OF FREEZ-
ING, LEAKING, LOOSE POSTS, OR EXCESSIVELY
LOW ELECTROLYTE LEVEL, DO NOT TEST. ACID
BURNS OR AN EXPLOSIVE CONDITION MAY
RESULT.
(1) Remove both battery cables, negative cable
first. The battery top, cables and posts should be
clean. Test battery with a hydrometer. If battery
charge is low the charge battery. Refer to Battery
Charging Procedures.(2) Connect a Volt/Ammeter/Load tester to the bat-
tery posts (Fig. 6). Rotate the load control knob of the
Carbon pile rheostat to apply a 300 amp load. Apply
this load for 15 seconds to remove the surface charge
from the battery, and return the control knob to off
(Fig. 7).
(3) Allow the battery to stabilize for 2 minutes,
and then verify open circuit voltage.
(4) Rotate the load control knob on the tester to
maintain 50% of the battery cold crank rating for 15
seconds (Fig. 8). Record the loaded voltage reading
and return the load control to off. Refer to the Bat-
tery Specifications at the rear of this Group.
(5) Voltage drop will vary according to battery
temperature at the time of the load test. Battery
temperature can be estimated by the temperature of
exposure over the preceding several hours. If the bat-
tery has been charged or boosted a few minutes prior
to the test, the battery would be slightly warmer.
Refer to Load Test Voltage Chart for proper loaded
voltage reading.
Fig. 5 Milliampere Meter ConnectionFig. 6 Volt-Ammeter Load Tester Connections
Fig. 7 Remove Surface Charge From Battery
NS/GSBATTERY 8A - 5
DIAGNOSIS AND TESTING (Continued)
coming from the module, replace the Memory Seat/
Mirror Module.
²If P9 low current battery is present at (cavity 5)
referenced to ground Z1 (cavity 1) of the seat switch,
verify the presence of the P9 voltage at the switch
outputs. If there is no output voltage from the
switch, replace the switch.
²If P9 voltage is present at the output of the
switch, but there is no reaction from the memory
seat/mirror module, verify that the P9 voltage is
present at the appropriate 21-way connector pins
into the module. If the P9 voltage is not present at
the 21-way connector, repair or replace the seat wir-
ing harness. If the verification check of the seat wir-
ing harness is correct, replace the control module.
(2) If the control module does not respond with a
relay click to a specific seat switch when actuated,
verify the continuity of the particular circuit between
the seat switch and the Memory Seat/Mirror Module.
If the P9 voltage is present at the correct input of the
21-way connector of the module when the switch is
actuated, but there is no response by the module,
replace the Memory Seat/Mirror Module.
(3) If the Memory Seat/Mirror Module responds
with a relay click when a seat switch is actuated for
a given direction, but there is no reaction from a seat
or recliner motor relating to that switch input, dis-
connect the 10-way connector from the control mod-
ule. Jumper the battery and ground from cavities 8
and 7 of the seat harness 10-way connector to the
proper cavities for the seat or recliner motor in ques-
tion and direction of travel desired. If the motor oper-
ates, replace the control module. If the motor does
not operate, verify continuity of the wiring into the
motor 2-way connector. Repair or replace the wiring
as necessary. If the wiring has continuity, and the
motor will not operate when fed directly, replace the
track assembly, since the motor/transmission combi-
nations are not designed to be serviced on an individ-
ual basis.
SEAT AND RECLINER POSITION SENSING
Seat and recliner position sense ground reference
circuit P28 BR/RD feed is from the memory seat/mir-
ror module (cavity 10) 21-way connector to each of
the position sense connectors.
Seat and recliner position sense +5 volt feed circuit
P29 BR/WT feed is from the memory seat/mirror
module (cavity 20) 21-way connector to each of the
position sense connectors.
To test for the presence of a sense voltage, a volt
meter must be used as follows:
²Connect the negative probe to the P28 circuit
(cavity 10) of the 21-way connector.
²Connect the positive probe to the P29 circuit
(cavity 20) of the 21-way connector and verify a volt-age reading between 3.5 and 5 volts when a seat or
recliner switch is activated.An internal timer in
the Memory Seat/Mirror Module (MSM Module)
regulates the length of time this voltage stays
active i.e., 3 seconds from the time that the
switch was activated, unless the switch is held
or while the transmission is out of PARK.If the
voltage is less than 3.5, there is a fault in the system
that is drawing it down. To troubleshoot this circuit,
disconnect the 25-way connector from the MSM Mod-
ule (this removes all of the vehicle mirror circuitry).
If the voltage is still less than 3.5, disconnect each of
the position sense connectors from each of the
motors. If the voltage remains less than 3.5, replace
the MSM Module. If the voltage increases when a
motor is disconnected from the system, determine if
the fault is in the wiring or the motor assembly.
Repair or replace the wire harness assembly as
needed. If the fault is in the motor position sensing
potentiometer, replace the track assembly.
²The potentiometers built onto the motor end-bell
provide voltages to the MSM Module through the
21-way connector, which change as follows, corre-
sponding to the given seat actuations. Refer to Seat
Actuations Table.
SERVICE PROCEDURES
REMOTE KEYLESS ENTRY (RKE) DATA LINK
The memory seat/mirror module interfaces with
the RKE via a serial data link (single wire). The pro-
gramming sequence to relate an RKE transmitter to
the chosen seat, recliner and side view mirror posi-
tions consists of the following steps:
(1) Adjust the seat, recliner and side view mirrors
to the desired position.
(2) Press momentarily and release memory switch
S.
(3) Press momentarily and release memory switch
1or2.
(4) Press momentarily and release a LOCK button
on an RKE transmitter.
(5) To program the second driver's position, follow
the previous sequence with a second transmitter.
(6) To recall either of the programmed positions
with an RKE transmitter, press momentarily and
release an UNLOCK button on one of the pro-
grammed RKE transmitters.An unprogrammed
RKE transmitter will have no effect on the sys-
tem.
(7) The RKE receiver uses the serial data link to
notify the module of a request from a programmed
transmitter, that an UNLOCK button has been
pressed. This UNLOCK request (from a transmitter
associated with either switch 1 or 2) will activate the
NSPOWER SEATS 8R - 9
DIAGNOSIS AND TESTING (Continued)
THROTTLE BODY....................... 64
THROTTLE POSITION SENSOR............ 65
UPSTREAM OXYGEN SENSOR............. 68
SPECIFICATIONS
TORQUE.............................. 72SPECIAL TOOLS
FUEL................................. 72
GENERAL INFORMATION
INTRODUCTION
All engines used in this section have a sequential
Multi-Port Electronic Fuel Injection system. The MPI
system is computer regulated and provides precise
air/fuel ratios for all driving conditions. The Power-
train Control Module (PCM) operates the fuel injec-
tion system.
The PCM regulates:
²Ignition timing
²Air/fuel ratio
²Emission control devices
²Cooling fan
²Charging system
²Idle speed
²Vehicle speed control
Various sensors provide the inputs necessary for
the PCM to correctly operate these systems. In addi-
tion to the sensors, various switches also provide
inputs to the PCM.
All inputs to the PCM are converted into signals.
The PCM can adapt its programming to meet chang-
ing operating conditions.
Fuel is injected into the intake port above the
intake valve in precise metered amounts through
electrically operated injectors. The PCM fires the
injectors in a specific sequence. Under most operat-
ing conditions, the PCM maintains an air fuel ratio
of 14.7 parts air to 1 part fuel by constantly adjust-
ing injector pulse width. Injector pulse width is the
length of time the injector is open.
The PCM adjusts injector pulse width by opening
and closing the ground path to the injector. Engine
RPM (speed) and manifold absolute pressure (air
density) are the primary inputs that determine injec-
tor pulse width.
MODES OF OPERATION
As input signals to the PCM change, the PCM
adjusts its response to output devices. For example,
the PCM must calculate a different injector pulse
width and ignition timing for idle than it does for
Wide Open Throttle (WOT). There are several differ-
ent modes of operation that determine how the PCM
responds to the various input signals.
There are two different areas of operation, OPEN
LOOP and CLOSED LOOP.
During OPEN LOOP modes the PCM receives
input signals and responds according to preset PCMprogramming. Input from the oxygen (O2S) sensor is
not monitored during OPEN LOOP modes.
During CLOSED LOOP modes the PCM does mon-
itor the O2S sensor input. This input indicates to the
PCM whether or not the calculated injector pulse
width results in the ideal air/fuel ratio of 14.7 parts
air to 1 part fuel. By monitoring the exhaust oxygen
content through the O2S sensor, the PCM can fine
tune the injector pulse width. Fine tuning injector
pulse width allows the PCM to achieve optimum fuel
economy combined with low emissions.
The multi-port fuel injection system has the follow-
ing modes of operation:
²Ignition switch ON (zero RPM)
²Engine start-up
²Engine warm-up
²Cruise (Idle)
²Acceleration
²Deceleration
²Wide Open Throttle
²Ignition switch OFF
The engine start-up (crank), engine warm-up, and
wide open throttle modes are OPEN LOOP modes.
Under most operating conditions, the acceleration,
deceleration, and cruise modes,with the engine at
operating temperatureare CLOSED LOOP modes.
IGNITION SWITCH ON (ZERO RPM) MODE
When the multi-port fuel injection system is acti-
vated by the ignition switch, the following actions
occur:
²The PCM determines atmospheric air pressure
from the MAP sensor input to determine basic fuel
strategy.
²The PCM monitors the coolant temperature sen-
sor and throttle position sensor input. The PCM mod-
ifies fuel strategy based on this input.
When the key is in the ON position and the engine
is not running (zero rpm), the Automatic Shutdown
(ASD) relay and fuel pump relay are not energized.
Therefore battery voltage is not supplied to the fuel
pump, ignition coil, fuel injectors or oxygen sensor
heating element.
ENGINE START-UP MODE
This is an OPEN LOOP mode. The following
actions occur when the starter motor is engaged.
If the PCM receives the camshaft position sensor
and crankshaft position sensor signals, it energizes
the ASD relay and fuel pump relay. These relays sup-
ply battery voltage to the fuel pump, fuel injectors,
14 - 30 FUEL SYSTEMNS
SPECIFICATIONS (Continued)
BOOST PRESSURE SENSOR
The Boost Pressure Sensor is mounted to the top of
the intake manifold. (Fig. 2) It is a sensor that mea-
sures both manifold vacuum and turbo boost, and it
also contains an integrated intake air temperature
sensor. The Boost Pressure Sensor takes the place of
the Mass Air Flow (MAF). In the Intake Air Temper-
ature Sensor component, there is a ceramic element
that changes its resistance based on temperature.
The ceramic element is part of an electronic circuit
connected to the PCM, and has a voltage applied to
it. The ceramic element is exposed to the air inside
the intake. This air has a cooling effect on the
ceramic element, and its resistance changes. This
causes the voltage flowing through the intake air
temperature circuit to vary. The voltage signal pro-
duced by the Intake Air Temperature Sensor changes
inversely to the temperature, and is measured by the
PCM. As a general rule, when the temperature of the
air in the intake is high, the voltage signal produced
by the Intake Air Temperature Sensor is low. The
component of the Boost Pressure Sensor that mea-
sures manifold vacuum and turbo boost produces a
voltage signal that is proportional to the pressure in
the inake manifold. When the intake manifold pres-
sure is low, the voltage is low, and when the pressure
is high, the voltage is high. The PCM uses the volt-
age signals from the Boost Pressure Sensor, and the
Intake Air Temperature Sensor to determine the
amount of air flowing through the intake manifold.
VEHICLE THEFT ALARM
The PCM can learn if the vehicle has a Vehicle
Theft Alarm (VTA) system. Once it detects the vehi-
cle having VTA,the controller can ONLY BE
USED ON VEHICLES WITH VTA.If the PCM is put it on a vehicle without VTA the
Glow Plug Lamp will start to blink and the vehicle
will not start.
The PCM cannot be flashed to remove the VTA.
BATTERY VOLTAGEÐPCM INPUT
The battery voltage input provides power to the
PCM. It also informs the PCM what voltage level is
being supplied by the generator once the vehicle is
running.
The battery input also provides the voltage that is
needed to keep the PCM memory alive. The memory
stores Diagnostic Trouble Code (DTC) messages.
Trouble codes will still be stored even if the battary
voltage is lost.
SENSOR RETURNÐPCM INPUT (ANALOG
GROUND)
Sensor Return provides a low noise Analog ground
reference for all system sensors.
SIGNAL GROUNDÐPCM INPUT
Signal ground provides a low noise ground to the
data link connector.
IGNITION CIRCUIT SENSEÐPCM INPUT
The ignition circuit sense input signals the PCM
that the ignition (key) switch has been turned to the
ON position. This signal initiates the glow plug con-
trol routine to begin the ªpre±heatº cycle.
START SIGNALÐPCM INPUT
This input tells the PCM that the engine starter is
being operated. This in turn will start the glow plug
ªpost±heatº cycle.
POWER GROUND
Provides a common ground for power devices (sole-
noid and relay devices).
NEEDLE MOVEMENT OR INSTRUMENTED FIRST
INJECTORÐPCM INPUT
This input from the PCM supplies a constant 30
mA electrical current source for the first injector sen-
sor. It will vary the voltage to this sensor when it
senses a mechanical movement within the injector
needle (pintle) of the number±1 cylinder fuel injector.
When this voltage has been determined by the PCM,
it will then control an output to the fuel timing sole-
noid (the fuel timing solenoid is located on the fuel
injection pump). Also refer to Fuel Injection Pump for
additional information.
The first injector sensor is a magnetic (inductive)
type.
Fig. 2 Boost Pressure Sensor Location
NS/GSFUEL SYSTEMÐ2.5L DIESEL ENGINE/2.0L GAS ENGINE 14 - 45
DESCRIPTION AND OPERATION (Continued)