CHEVROLET PLYMOUTH ACCLAIM 1993 Service Manual

2.2L/2.5L SINGLE POINT FUEL INJECTIONÐON-BOARD DIAGNOSTICS INDEX
page page
60-Way PCM Wiring Connector .............. 46
Circuit Actuation Test Mode ................ 45
Diagnostic Trouble Code Description .......... 42
General Information ....................... 41
High and Low Limits ...................... 42
Ignition Timing Procedure .................. 46 Monitored Circuits
........................ 41
Non-Monitored Circuits .................... 42
State Display Test Mode ................... 45
Systems Test ........................... 45
Throttle Body Minimum Air Flow Check Procedure.46
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 50 to 100 vehicle key on/off
cycles. Certain criteria must be met for a diagnostic trou-
ble code to be entered into powertrain control module
(PCM) memory. The criteria may be a specific range
of engine RPM, engine temperature, and/or input
voltage to the PCM. It is possible that a diagnostic trouble code for a
monitored 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 exam-
ple , assume that one of the diagnostic trouble code
criteria for a certain sensor circuit is that the engine
must be operating between 750 and 2000 RPM to be
monitored for a diagnostic trouble code. 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 diagnostic 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 for which
the PCM does not monitor and set diagnostic trouble
codes. Refer to Monitored Circuits and Non-Moni-
tored Circuits in this section. Stored diagnostic trouble codes can be displayed by
cycling the ignition key On - Off - On - Off - On.
Also, the technician can display fault information us-
ing the DRB II scan tool. The DRBII scan tool con-
nects to the data link connector in the vehicle (Fig.
1,2or3).
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, and if the circuit 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
Fig. 1 Data Link Connector LocationÐAA and AP Vehicles
Fig. 2 Data Link Connector LocationÐAC Vehicles
Ä FUEL SYSTEMS 14 - 41

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 PCM does not monitor the following circuits,
systems and conditions that could have malfunctions
that result in driveability problems. Diagnostic trou-
ble codes may not be displayed for these conditions.
However, problems with these systems may cause di-
agnostic trouble codes to be displayed for other sys-
tems. For example, a fuel pressure problem will not
register a fault directly, but could cause a rich or
lean condition. This could cause an oxygen sensor
fault to be stored in the PCM. Fuel Pressure - Fuel pressure is controlled by the
fuel pressure regulator. The PCM cannot detect a
clogged fuel pump inlet filter, clogged in-line fuel fil-
ter, or a pinched fuel supply or return line. However,
these could result in a rich or lean condition causing
an oxygen sensor fault. 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. The PCM also cannot detect an
incorrectly indexed distributor. 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 the fuel injector is clogged, the pintle 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 the exhaust stream oxygen content through
the oxygen sensor 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 ele-
ment. Evaporative System - The PCM will not detect a
restricted, plugged or loaded evaporative purge can-
ister. Vacuum Assist - Leaks or restrictions in the vac-
uum circuits of vacuum assisted engine control sys-
tem devices are not monitored by the PCM. However,
these could result in a MAP sensor fault being stored
in the PCM. PCM System Ground - The PCM cannot deter-
mine a poor system ground. However, a diagnostic
trouble code may be generated as a result of this con-
dition. 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 es-
tablished high and low limits that are programmed
into it for that device. If the input voltage is not
within specifications 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
When a diagnostic trouble code appears, it indi-
cates the powertrain control module (PCM) has rec-
ognized an abnormal condition in the system.
Diagnostic trouble codes can be obtained from the
malfunction indicator lamp (instrument panel 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.
Fig. 3 Data Link Connector LocationÐAG and AJ Vehicles
14 - 42 FUEL SYSTEMS Ä

DIAGNOSTIC TROUBLE CODE DESCRIPTION
Ä FUEL SYSTEMS 14 - 43

DIAGNOSTIC TROUBLE CODE DESCRIPTION
14 - 44 FUEL SYSTEMS Ä

SYSTEMS TEST
WARNING: APPLY PARKING BRAKE AND/OR
BLOCK WHEELS BEFORE PERFORMING A TEST
WITH THE ENGINE OPERATING.
OBTAINING DIAGNOSTIC TROUBLE CODES
(1) Connect DRBII scan tool to the data link con-
nector located in the engine compartment near the
powertrain control module (PCM). (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 3 seconds then go out (bulb
check).
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 po-
sition versus an open circuit, a short circuit, or a de-
fective 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 ei-
ther State Display Inputs and Outputs or State Dis-
play Sensors.
STATE DISPLAY INPUTS AND OUTPUTS
Connect the DRBII scan tool to the vehicle and ac-
cess 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 (automatic transaxle only)
Speed Control Resume
Brake Switch
Speed Control On/Off
Speed Control Set
A/C Switch Sense
S/C (Speed Control) Vent Solenoid
S/C (Speed Control) Vacuum Solenoid
Torque Converter Clutch Solenoid (3 speed auto-
matic transaxle)
A/C Clutch Relay
EGR Solenoid
Auto Shutdown Relay
Radiator Fan Relay
Purge Solenoid
Malfunction Indicator (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
Coolant Temperature
Coolant Temp Sensor
Throttle Position
Minimum Throttle
Battery Voltage
MAP Sensor Reading
Idle Air Control Motor Position
Added Adaptive Fuel
Adaptive Fuel Factor
Barometric Pressure
Min Airflow Idl Spd
Engine Speed
Fault #1 Key-On Info
Module Spark Advance
Speed Control Target
Fault #2 Key-On Info
Fault #3 Key-On Info
Speed Control Status
Charging System Goal
Theft Alarm Status
Speed Control Switch Voltage
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.). With the exception of an intermit-
tent condition, if a device functions properly during
its test, it can be assumed that the device, its associ-
ated wiring, and its driver circuit are in working or-
der.
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
Fuel Injector #1
Idle Air Control Motor Open/Close
Ä FUEL SYSTEMS 14 - 45

Radiator Fan Relay
A/C Clutch Relay
Auto Shutdown Relay
Purge Solenoid
S/C Servo Solenoids
Generator Field
Tachometer Output
Torque Converter Clutch Solenoid (3 speed auto-
matic transaxle only)
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) Connect DRBII scan tool.
(2) Remove air cleaner assembly. Plug the heated
air door vacuum hose. (3) Warm engine in Park or Neutral until the cool-
ing fan has cycled on and off at least once. (4) Hook-up timing check device and tachometer.
(5) Disconnect the coolant temperature sensor and
set basic timing to 12ÉBTDC 62ÉBTDC.
(6) Shut off engine. Reconnect coolant temperature
sensor. (7) Disconnect the PCV valve hose from the intake
manifold nipple. (8) Attach Air Metering Fitting #6457 (Fig. 4) to
the intake manifold PCV nipple. (9) Restart the engine, allow engine to idle for at
least one minute. (10) Using the DRBII scan tool, Access Min Air-
flow Idle Spd in the sensor read test mode. (11) The following will then occur:
² Idle air control motor will fully close.
² Idle spark advance will become fixed.
² Idle fuel will be provided at a set value.
² Engine RPM will be displayed on DRBII scan tool.
(12) Check idle RPM with tachometer. If idle RPM is within the specifications listed below, then the
throttle body minimum air flow is set correctly.
If idle RPM is not within specification replace
throttle body. (13) Shut off engine.
(14) Remove Special Tool number 6457 from in-
take manifold PCV nipple. Reinstall the PCV valve
hose. (15) Remove DRBII scan tool.
(16) Reinstall air cleaner assembly. Reinstall
heated air door vacuum hose. (17) Disconnect timing check device and tachome-
ter.
IGNITION TIMING PROCEDURE
Refer to Group 8D Ignition System
60-WAY PCM WIRING CONNECTOR
Refer to the powertrain control module (PCM) wir-
ing connector descriptions for information regarding
wire colors and cavity numbers (Fig. 5).
Fig. 4 Air Metering Fitting
IDLE SPECIFICATIONS
14 - 46 FUEL SYSTEMS Ä

Fig. 5 PCM Wiring Connector Cavity Description
Ä FUEL SYSTEMS 14 - 47

2.2L/2.5L SINGLE POINT FUEL INJECTIONÐSERVICE PROCEDURES INDEX
page page
Canister Purge Solenoid ................... 53
Electric Exhaust Gas Recirculation Transducer (EET) Service ............................... 53
Fuel Fitting ............................. 50
Fuel Injector ............................ 51
Fuel Lines and Hoses ..................... 48
Fuel Pressure Regulator ................... 51 Fuel System Pressure Release Procedure
...... 48
Heated Oxygen Sensor (O
2Sensor) .......... 54
Idle Air Control Motor ..................... 53
Manifold Absolute Pressure Sensor ........... 53
PCM Service ............................ 54
Throttle Body ............................ 48
Throttle Position Sensor ................... 52
FUEL LINES AND HOSES
Perform the Fuel System Pressure Relief Procedure
before servicing the fuel system. The procedure must
be done to bleed fuel pressure from the system before
removing clamps or hoses. Use care when removing fuel hoses to prevent dam-
age to hose or hose nipple. Always use new hose
clamps, of the correct type, during reassembly. Tighten
hose clamps to 1 N Im (10 in. lbs.) torque. Do not use
aviation style clamps on this system or hose
damage may result.
FUEL SYSTEM PRESSURE RELEASE PROCEDURE
CAUTION: Before servicing the fuel pump, fuel lines,
fuel filter, throttle body, or fuel injector, release fuel
system pressure.
(1) Loosen fuel filler cap to release fuel tank pres-
sure. (2) Disconnect injector wiring harness connector at
edge of throttle body (Fig. 1). (3) Connect a jumper wire between terminal Num-
ber 1 of the injector harness and engine ground. (4) Connect a jumper wire to the positive terminal
Number 2 of the injector harness and touch the battery
positive post for no longer than 5 seconds . This
releases system pressure. (5) Remove jumper wires.
(6) Continue fuel system service.
THROTTLE BODY
CAUTION: The fuel system is under a constant pres-
sure of 270 kPa (39 psi). When servicing the fuel
portion of the throttle body, release fuel pressure
before disconnecting any tubes. Refer to the fuel
pressure release procedure.
Always reassemble throttle body components with
new O-rings and seals where applicable. Never use
silicone lubricants on O-rings or seals, damage may
result. Use care when removing fuel tubes to prevent
damage to quick connect fittings or tube ends. Refer to Fuel Hoses, Clamps, and Quick Connect Fittings
in the Fuel Delivery Section of this Group.
REMOVAL
(1) Remove air cleaner (Fig. 2).
(2) Perform fuel system pressure release procedure.
(3) Disconnect negative battery cable.
(4) Disconnect vacuum hoses and electrical connec-
tors (Fig. 3).
Fig. 1 Injector Harness Connector
Fig. 2 Throttle Body and Air Cleaner Assembly
14 - 48 FUEL SYSTEMS Ä

Fig. 3 Throttle Body
Ä FUEL SYSTEMS 14 - 49

(5) Remove throttle cable. If equipped, remove the
speed control and transaxle kickdown cables. (6) Remove return spring.
(7) Loosen fuel tube clamp on valve cover (Fig. 4).
(8) Wipe quick connect fittings to remove any dirt.
Remove fuel intake and return tubes. Refer to Fuel
Hoses, Clamps and Quick Connect Fittings in the
Fuel Delivery Section of this Group. Place a shop
towel under the connections to absorb any fuel spilled. (9) Remove throttle body mounting screws and lift
throttle body from vehicle. Remove throttle body gas-
ket from intake manifold.
INSTALLATION
(1) Using a new gasket, install throttle body and
tighten mounting screws to 20 N Im (175 in. lbs.)
torque. (2) Lubricate the ends of the fuel supply and return
tubes with clean 30 weight oil. Connect fuel lines to
quick connect fittings. Refer to Fuel Hoses, Clamps
and Quick Connect Fittings in the Fuel Delivery
Section of this Group . After the fuel tubes are
connected to the fittings, pull on the tubes to ensure
that they are fully inserted and locked into position. (3) Tighten the fuel tube clamp on the valve cover.
(4) Install return spring.
(5) Install throttle cable. If equipped, install kick-
down and speed control cables. (6) Install wiring connectors and vacuum hoses.
(7) Install air cleaner.
(8) Reconnect negative battery cable.
CAUTION: When using the ASD Fuel System Test, the
Auto Shutdown (ASD) Relay remains energized for
either 7 minutes, until the test is stopped, or until the
ignition switch is turned to the Off position. (9) With the ignition key in ON position, access the
DRBII scan tool ASD Fuel System Test to pressurize
the fuel system. Check for leaks.
FUEL FITTING
REMOVAL
(1) Remove air cleaner assembly.
(2) Perform Fuel System Pressure Release proce-
dure. (3) Disconnect negative battery cable.
(4) Loosen fuel tube clamp on valve cover.
(5) Wipe any dirt from around quick connect fittings.
(Fig. 5) Place a shop towel under the connections to
catch any spilled fuel. Remove fuel tubes from quick
connect fittings. Refer to Fuel Hoses, Clamps and
Quick Connect Fittings in the Fuel Delivery Sec-
tion of this Group .
(6) Remove each fitting from throttle body and note
inlet diameter. Remove copper washers.
INSTALLATION
(1) Replace copper washers with new washers.
(2) Install fuel fittings in proper ports and tighten to
20 N Im (175 in. lbs.) torque.
(3) Lubricate ends of the fuel tubes with 30 weight
oil. Insert the tubes into the quick connect fittings.
Refer to Fuel Hoses, Clamps and Quick Connect
Fittings in the Fuel Delivery Section of this
Group . After the fuel tubes are connected to the
fittings, pull on the tubes to ensure that they are fully
inserted and locked into position. (4) Tighten fuel tube clamp on valve cover.
(5) Reconnect negative battery cable.
Fig. 5 Servicing Fuel Fitting
Fig. 4 Fuel Line Clamp
14 - 50 FUEL SYSTEMS Ä