CHEVROLET PLYMOUTH ACCLAIM 1993 Service Manual

Fig. 17 Power Brake Booster Hose
Fig. 18 Speed Control Vacuum
Ä FUEL SYSTEMS 14 - 161

3.3L AND 3.8L MULTI-PORT FUEL INJECTIONÐON-BOARD DIAGNOSTICS INDEX
page page
60-Way Pcm Wiring Connector ............. 167
Circuit Actuation Test Mode ................ 166
Diagnostic Trouble Code Description ......... 163
General Information ...................... 162
High and Low Limits ..................... 163
Monitored Circuits ....................... 162 Non-Monitored Circuits
................... 162
State Display Test Mode .................. 163
System Tests .......................... 163
Throttle Body Minimum Air Flow Check Procedure ............................ 166
GENERAL INFORMATION
The powertrain control module (PCM) has been
programmed to monitor many different circuits of the
fuel injection system. If a problem is sensed with a
monitored circuit often enough to indicate an actual
problem, the PCM stores a fault. If the problem is re-
paired or ceases to exist, the PCM cancels the Diag-
nostic trouble code after 51 vehicle key on/off cycles. Certain criteria must be met for a diagnostic trou-
ble code to be entered into the PCM memory. The
criteria may be a specific range of engine RPM, en-
gine temperature, and/or input voltage to the PCM. It is possible a diagnostic trouble code for a moni-
tored circuit may not be entered into memory even
though a malfunction has occurred. This may happen
because one of the diagnostic trouble code criteria for
the circuit has not been met. For example, assume
one of the diagnostic trouble code criteria for a sen-
sor circuit is the engine must be operating between
750 and 2000 RPM. If the sensor output circuit
shorts to ground when engine RPM is above 2400
RPM (resulting i n a 0 volt input to the PCM) a diag-
nostic trouble code will not be entered into memory.
This is because the condition does not occur within
the specified RPM range. There are several operating conditions that the
PCM does not monitor and set diagnostic trouble
codes for. Refer to Monitored Circuits and Non-Mon-
itored Circuits in this section. Stored diagnostic trouble codes can be displayed ei-
ther by cycling the ignition key On - Off - On - Off -
On, or through use of the DRBII scan tool. The
DRBII scan tool connects to the data link connector
in the vehicle (Fig. 1).
MONITORED CIRCUITS
The powertrain control module (PCM) can detect
certain fault conditions in the fuel injection system. Open or Shorted Circuit - The PCM can deter-
mine if the sensor output (input to PCM) is within
proper range. Also, the PCM can determine if the cir-
cuit is open or shorted. Output Device Current Flow - The PCM senses whether the output devices are hooked up. If there is
a problem with the circuit, the PCM senses whether
the circuit is open, shorted to ground, or shorted
high. Oxygen Sensor - The PCM can determine if the
oxygen sensor is switching between rich and lean
once the system has entered closed loop. Refer to
Modes of Operation in this section for an explanation
of closed loop operation.
NON-MONITORED CIRCUITS
The powertrain control module (PCM) does not
monitor the following circuits, systems and condi-
tions that could have malfunctions that result in
driveability problems. Diagnostic trouble codes may
not be displayed for these conditions. However, prob-
lems with these systems may cause diagnostic trou-
ble codes to be displayed for other systems. For
example, a fuel pressure problem will not register a
fault directly, but could cause a rich or lean condi-
tion. This could cause an oxygen sensor fault to be
stored in the PCM. Fuel Pressure - Fuel pressure is controlled by the
vacuum assisted fuel pressure regulator. The PCM
cannot detect a clogged fuel pump inlet filter, clogged
in-line fuel filter, or a pinched fuel supply or return
Fig. 1 Powertrain Control Module (PCM)
14 - 162 FUEL SYSTEMS Ä

line. However, these could result in a rich or lean
condition causing an oxygen sensor fault to be stored in
the PCM. Secondary Ignition Circuit - The PCM cannot
detect an inoperative ignition coil, fouled or worn spark
plugs, ignition cross firing, or open spark plug cables. Engine Timing - The PCM cannot detect an incor-
rectly indexed timing chain, camshaft sprocket and
crankshaft sprocket. However, these could result in a
rich or lean condition causing an oxygen sensor fault to
be stored in the PCM. Cylinder Compression - The PCM cannot detect
uneven, low, or high engine cylinder compression. Exhaust System - The PCM cannot detect a
plugged, restricted or leaking exhaust system. Fuel Injector Malfunctions - The PCM cannot
determine if a fuel injector is clogged, the needle is
sticking or the wrong injector is installed. However,
these could result in a rich or lean condition causing an
oxygen sensor fault to be stored in the PCM. Excessive Oil Consumption - Although the PCM
monitors exhaust stream oxygen content when the
system is in closed loop, it cannot determine excessive
oil consumption. Throttle Body Air Flow - The PCM cannot detect a
clogged or restricted air cleaner inlet or filter element. Evaporative System - The PCM will not detect a
restricted, plugged or loaded evaporative purge canis-
ter. Vacuum Assist - Leaks or restrictions in the
vacuum circuits of vacuum assisted engine control
system devices are not monitored by the PCM. How-
ever, these could result in a MAP sensor fault being
stored in the PCM. PCM System Ground - The PCM cannot determine
a poor system ground. However, a diagnostic trouble
code may be generated as a result of this condition. PCM Connector Engagement - The PCM cannot
determine spread or damaged connector pins. How-
ever, a diagnostic trouble code may be generated as a
result of this condition.
HIGH AND LOW LIMITS
The powertrain control module (PCM) compares in-
put signal voltages from each input device with estab-
lished high and low limits for the device. If the input
voltage is not within limits and other diagnostic
trouble code criteria are met, a diagnostic trouble code
will be stored in memory. Other diagnostic trouble code
criteria might include engine RPM limits or input
voltages from other sensors or switches that must be
present before a fault condition can be verified.
DIAGNOSTIC TROUBLE CODE DESCRIPTION
A diagnostic trouble code indicates that the power-
train control module (PCM) has recognized an abnor- mal condition in the system. Diagnostic trouble codes
can be obtained from the malfunction indicator lamp
(Check Engine lamp on the instrument panel) or from
the DRBII scan tool. Diagnostic trouble codes indicate
the results of a failure but do not identify the failed
component directly.
SYSTEM TESTS
WARNING: APPLY PARKING BRAKE AND/OR BLOCK
WHEELS BEFORE PERFORMING ANY TEST ON AN
OPERATING ENGINE.
OBTAINING DIAGNOSTIC TROUBLE CODES
(1) Connect the DRBII scan tool to the data link
connector located in the engine compartment near the
driver side strut tower (Fig. 1). (2) Start the engine if possible, cycle the transaxle
selector and the A/Cswitch if applicable. Shut off the
engine. (3) Turn the ignition switch on, access Read Fault
Screen. Record all the fault messages shown on the
DRBII scan tool. Observe the malfunction indicator
lamp (check engine lamp on the instrument panel). The
lamp should light for 2 seconds then go out (bulb
check). Diagnostic trouble code erasure; access erase
diagnostic trouble code data
STATE DISPLAY TEST MODE
The switch inputs used by the powertrain control
module (PCM) have only two recognized states, HIGH
and LOW. For this reason, the PCM cannot recognize
the difference between a selected switch position ver-
sus an open circuit, a short circuit, or a defective
switch. If the change is displayed, it can be assumed
that the entire switch circuit to the PCM is functional.
From the state display screen access either State
Display Inputs and Outputs or State Display Sensors.
STATE DISPLAY INPUTS AND OUTPUTS
Connect the DRBII scan tool to the vehicle and access
the State Display screen. Then access Inputs and
Outputs. The following is a list of the engine control
system functions accessible through the Inputs and
Outputs screen. Park/Neutral Switch
Speed Control Resume
Brake Switch
Speed Control On/Off
Speed Control Set
A/C Switch Sense
S/C Vent Solenoid
Ä FUEL SYSTEMS 14 - 163

DIAGNOSTIC TROUBLE CODE DESCRIPTION
14 - 164 FUEL SYSTEMS Ä

DIAGNOSTIC TROUBLE CODE DESCRIPTION (CON'T)
Ä FUEL SYSTEMS 14 - 165

S/C Vacuum Solenoid
A/C Clutch Relay
EGR Solenoid
Auto Shutdown Relay
Radiator Fan Relay
Purge Solenoid
Malfunction Indicator Lamp (Check Engine Lamp)
STATE DISPLAY SENSORS
Connect the DRBII scan tool to the vehicle and ac-
cess the State Display screen. Then access Sensor
Display. The following is a list of the engine control
system functions accessible through the Sensor Dis-
play screen. Oxygen Sensor Signal
Engine Coolant Temperature
Engine Coolant Temp Sensor
Throttle Position
Minimum Throttle
Battery Voltage
MAP Sensor Reading
Idle Air Control Motor Position
Adaptive Fuel Factor
Barometric Pressure
Min Airflow Idle Spd (speed)
Engine Speed
DIS Sensor Status
Fault #1 Key-On Info
Module Spark Advance
Speed Control Target
Fault #2 Key-on Info
Fault #3 Key-on Info
Speed Control Status
Speed Control Switch Voltage
Charging System Goal
Theft Alarm Status
Map Sensor Voltage
Vehicle Speed
Oxygen Sensor State
MAP Gauge Reading
Throttle Opening (percentage)
Total Spark Advance
CIRCUIT ACTUATION TEST MODE
The circuit actuation test mode checks for proper
operation of output circuits or devices which the pow-
ertrain control module (PCM) cannot internally rec-
ognize. The PCM can attempt to activate these
outputs and allow an observer to verify proper oper-
ation. Most of the tests provide an audible or visual
indication of device operation (click of relay contacts,
spray fuel, etc.). Except for intermittent conditions, if
a device functions properly during testing, assume
the device, its associated wiring, and driver circuit
working correctly.
OBTAINING CIRCUIT ACTUATION TEST
Connect the DRBII scan tool to the vehicle and ac-
cess the Actuators screen. The following is a list of
the engine control system functions accessible
through Actuators screens. Stop All Tests
Ignition Coil #1
Ignition Coil #2
Ignition Coil #3
Fuel Injector #1
Fuel Injector #2
Fuel Injector #3
Fuel Injector #4
Fuel Injector #5
Fuel Injector #6
Idle Air Control Motor Open/Close
Radiator Fan Relay
A/C Clutch Relay
Auto Shutdown Relay
EVAP Purge Solenoid
S/C Servo Solenoids
Generator Field
EGR Solenoid
All Solenoids/Relays
ASD Fuel System Test
Speed Control Vacuum Solenoid
Speed Control Vent Solenoid
THROTTLE BODY MINIMUM AIR FLOW CHECK
PROCEDURE
(1) Warm engine in Park or Neutral until the cool-
ing fan has cycled on and off at least once. (2) Ensure that all accessories are off.
(3) Shut off engine.
(4) Disconnect the PCV valve hose from the intake
manifold nipple. (5) Attach Air Metering Fitting #6457 (0.125 in.
orifice) to the intake manifold PCV nipple (Fig. 2).
(6) Disconnect the 3/16 inch idle purge line from
the throttle body nipple. Cap the 3/16 inch nipple. (7) Connect DRBII scan tool to vehicle.
(8) Restart the engine. Allow engine to idle for at
least one minute. (9) Using the DRBII scan tool, access Min. Airflow
Idle Spd.
Fig. 2 Air Metering Fitting #6457
14 - 166 FUEL SYSTEMS Ä

(10) The following will then occur:
² Idle air control motor will fully close.
² Idle spark advance will become fixed.
² Engine RPM will be displayed on DRBII scan tool.
(11) If idle RPM is within the range shown in the
Idle Specification chart, throttle body minimum air-
flow is set correctly.
(12) If idle RPM is not within specifications, shut off
the engine and clean the throttle body as follows: (a) Remove the throttle body from engine.
WARNING: CLEAN THROTTLE BODY IN A WELL
VENTILATED AREA. WEAR RUBBER OF BUTYL
GLOVES, DO NOT LET MOPAR PARTS CLEANER
COME IN CONTACT WITH EYES OR SKIN. AVOID
INGESTING THE CLEANER. WASH THOROUGHLY
AFTER USING CLEANER. (b) While holding the throttle open, spray the
entire throttle body bore and the manifold side of the
throttle plate with Mopar Parts Cleaner. Only use
Mopar Parts Cleaner to clean the throttle body. (c) Using a soft scuff pad, clean the top and bottom
of throttle body bore and the edges and manifold side
of the throttle blade. The edges of the throttle
blade and portions of the throttle bore that are
closest to the throttle blade when is closed,
must be free of deposits. (d) Use compressed air to dry the throttle body.
(e) Inspect throttle body for foreign material.
(f) Install throttle body on manifold.
(g) Repeat steps 1 through 14. If the minimum air
flow is still not within specifications, the problem is
caused by the throttle body. Replace the throttle
body.
(13) Shut off engine.
(14) Remove Air Metering Fitting #6457 from the
intake manifold PCV nipple. Reinstall the PCV valve
hose. (15) Uncap the throttle body idle purge nipple and
connect the idle purge line. (16) Remove DRBII scan tool.
60-WAY PCM WIRING CONNECTOR
Refer to the PCM wiring connector diagram (Fig. 3)
for wire colors and cavity numbers.
IDLE SPECIFICATIONS
Ä FUEL SYSTEMS 14 - 167

Fig. 3 60-Way PCM Wiring Connector
14 - 168 FUEL SYSTEMS Ä

3.3L AND 3.8L MULTI-PORT FUEL INJECTIONÐSERVICE PROCEDURES INDEX
page page
Camshaft Position Sensor Service ........... 176
Crankshaft Position Sensor ................ 176
EVAP Canister Purge Solenoid Service ....... 175
Fuel Injector ........................... 174
Fuel Injector Rail Assembly ................ 170
Fuel Pressure Regulator .................. 173
Fuel System Pressure Release Procedure ..... 169 Heated Oxygen Sensor (O
2Sensor) Service . . . 177
Idle Air Control Motor .................... 170
Manifold Absolute Pressure (MAP) Sensor ..... 175
PCM Service ........................... 175
Throttle Body ........................... 169
Throttle Body Removal ................... 169
Throttle Position Sensor .................. 169
THROTTLE BODY REMOVAL
(1) Disconnect negative battery cable.
(2) Remove the air cleaner to throttle body hose
clamp. Remove the nut holding the air cleaner as-
sembly to the air cleaner bracket. Remove the air
cleaner (Fig. 1). (3) Remove throttle and the speed control cables.
(4) Disconnect electrical connectors from the idle
air control motor and throttle position sensor (TPS). (5) Disconnect vacuum hoses from throttle body.
(6) Remove throttle body to intake manifold at-
taching nuts. (7) Remove throttle body and gasket.
(8) Reverse the above procedure for installation.
THROTTLE BODY
When servicing throttle body components, always
reassemble components with new O-rings and seals
where applicable (Fig. 2). Never use lubricants on
O-rings or seals, damage may result. If assembly of component is difficult, use water to aid assembly.
Use care when removing hoses to prevent damage to
hose or hose nipple.
FUEL SYSTEM PRESSURE RELEASE PROCEDURE
WARNING: THE 3.3L AND 3.8L MPI FUEL SYSTEMS
ARE UNDER A CONSTANT PRESSURE OF AP-
PROXIMATELY 330 KPA (48 PSI). RELEASE FUEL
SYSTEM PRESSURE BEFORE SERVICING THE
FUEL PUMP, FUEL LINES, FUEL FILTER, THROT-
TLE BODY OR FUEL INJECTORS.
(1) Disconnect negative cable from battery.
(2) Remove fuel filler cap.
(3) Remove the protective cap from the fuel pres-
sure test port on the fuel rail (Fig. 3). (4) Place the open end of fuel pressure release
hose, tool number C-4799-1, into an approved gaso-
line container. Connect the other end of hose
C-4799-1 to the fuel pressure test port. Fuel pressure
will bleed off through the hose into the gasoline con-
tainer. Fuel gauge C-4799-A contains hose C-4799-1. (5) Continue fuel system service.
THROTTLE POSITION SENSOR
REMOVAL
(1) Disconnect negative cable from battery.
(2) Remove electrical connector from throttle posi-
tion sensor. (3) Remove throttle position sensor mounting
screws (Fig. 4). (4) Lift throttle position sensor off throttle shaft.
INSTALLATION
(1) Install throttle position sensor on throttle shaft.
Install mounting screws. Tighten screw to 2 N Im (17
in. lbs.) torque. (2) Connect electrical connector to throttle position
sensor. (3) Connect negative cable to battery.Fig. 1 Throttle Body Assembly
Ä FUEL SYSTEMS 14 - 169

IDLE AIR CONTROL MOTOR
REMOVAL
(1) Disconnect negative cable from battery.
(2) Remove electrical connector from idle air con-
trol motor. (3) Remove idle air control motor mounting screws
(Fig. 5). (4) Remove idle air control motor from throttle
body. Ensure the O-ring is removed with the motor.
INSTALLATION
(1) New idle air control motors have a new O-ring
installed on it. If pintle measures more than 1 inch
(25 mm) it must be retracted. Use the DRBII scan
tool Idle Air Control Motor Open/Close Test to re-
tract the pintle (battery must be connected.) (2) Carefully place idle air control motor into
throttle body. (3) Install mounting screws. Tighten screws to 2
N Im (17 in. lbs.) torque.
(4) Connect electrical connector to idle air control
motor. (5) Connect negative cable to battery.
FUEL INJECTOR RAIL ASSEMBLY
REMOVAL
(1) Perform fuel system pressure release procedure
before servicing or starting repairs. Refer to Fuel
System Pressure Release Procedure in this section. (2) Disconnect negative cable from battery.
(3) Remove air cleaner and hose assembly (Fig. 1).
Fig. 2 Throttle Body
Fig. 3 Fuel Pressure Test PortFig. 4 Servicing Throttle Position Sensor
14 - 170 FUEL SYSTEMS Ä