5.FUEL PUMP MODULE
If there are no possible causes remaining, view repair.
Repair
Replace the Fuel Pump Module.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
6.O2 SENSOR OPERATION
Turn the ignition off.
NOTE: Wait a minimum of 10 minutes to allow the O2 Sensor and Exhaust System to cool down before
continuing the test.
Ignition on, engine not running.
With the scan tool, monitor all of the O2 Sensor voltage readings.
Is the voltage above 4.5 volts?
Ye s>>
Go To 7
No>>
Go To 13
7.O2 SENSOR HEATER OPERATION
Turn the ignition off.
NOTE: Wait a minimum of 10 minutes to allow the O2 Sensor to cool down before continuing the test.
Ignition on, engine not running.
With the scan tool, actuate the 1/1 O2 Heater Test.
With the scan tool, monitor all O2 Sensor voltage readings for at least 2 minutes.
Does the voltage stay above 4.5 volts for any of the O2 Sensors?
Ye s>>
Replace the O2 Sensor that had the voltage reading above 4.5 volts.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
No>>
Go To 8
8.TP SENSOR VOLTAGE GREATER THAN 0.92 OF A VOLT WITH THROTTLE CLOSED
With the scan tool, read TP Sensor voltage.
NOTE: The throttle must be against the stop.
Isthevoltage0.92ofavoltorlesswiththeThrottleclosed?
Ye s>>
Go To 9
No>>
Check for a binding throttle condition. If OK, replace the Throttle Position Sensor.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
9.TP SENSOR SWEEP
With the scan tool, read the TP Sensor voltage.
While monitoring the scan tool, slowly open and close the throttle.
Does the voltage increase and decrease smoothly?
Ye s>>
Go To 10
No>>
ReplacetheThrottlePositionSensor.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
12.ENGINE MECHANICAL PROBLEM
Check for any of the following conditions/mechanical problems.
AIR INDUCTION SYSTEM - must be free from leaks.
ENGINE VACUUM - must be at least 13 inches in neutral
ENGINE VALVE TIMING - must be within specifications
ENGINE COMPRESSION - must be within specifications
ENGINE EXHAUST SYSTEM - must be free of any restrictions or leaks.
ENGINE PCV SYSTEM - must flow freely
TORQUE CONVERTER STALL SPEED - must be within specifications
POWER BRAKE BOOSTER - no internal vacuum leaks
FUEL - must be free of contamination
FUEL INJECTOR - plugged or restricted injector; control wire not connectedtocorrectinjector
Are there any engine mechanical problems?
Ye s>>
Repair as necessary.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
No>>
Refer to the INTERMITTENT CONDITIONSymptom (Diagnostic Procedure).
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
13.O2 SENSOR
NOTE: Wait a minimum of 10 minutes to allow the O2 Sensor to cool down before continuing the test.
Ignition on, engine not running.
Disconnect the harness connector(s) of the O2 Sensor(s) that had a voltagereading below 4.5 volts in the previous
step.
With the scan tool, monitor the O2 Sensor voltage reading(s).
Is the voltage above 4.5 volts for any of the O2 Sensors?
Ye s>>
Replace the O2 Sensor that had a voltage reading above 4.5 volts.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
No>>
Go To 14
14.(K43) O2 SENSOR 2/1 SIGNAL CIRCUIT SHORTED TO GROUND
Turn the ignition off.
Disconnect the PCM harness connectors.
Measure the resistance between ground and the (K43) O2 Sensor 2/1
Signal circuit at the PCM harness connector.
Istheresistancebelow100ohms?
Ye s>>
Repair the short to ground in the (K43) O2 Sensor 2/1 Sig-
nal circuit.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to
9 - ENGINE - STANDARD PROCEDURE)
No>>
Go To 15
Theory of Operation
The fuel feedback system will maintain a stoiciometric fuel/air mixture,14.7:1, by modifying the injector pulsewidth
according to the oxygen content of the exhaust gas. The PCM makes short termand long term fuel corrections to
maintain stoiciometric fuel/air ratio for best catalytic converter efficiency. Short term fuel correction is based on
upstream O2 sensor output and is designed for quick engine response. The long term fuel correction compensated
for variations in the engine specifications, sensor tolerances and component aging and is designed to correct rich
and lean conditions over a longer period of time.
When Monitored:
With the engine running in closed loop mode, the ambient/battery temperature above 20 deg. F and altitude
below 8500 ft.
Set Condition:
If the PCM multiplies short term compensation by long term adaptive and a purge fuel multiplier and the result
is below a certain value for 30 seconds over two trips, a freeze frame is stored, the MIL illuminates and a
trouble code is stored. Two Trip Fault. Three good trips to turn off the MIL.
Possible Causes
O2 SENSOR
(K43) O2 SENSOR 2/1 SIGNAL CIRCUIT OPEN
(K43) O2 SENSOR 2/1 SIGNAL CIRCUIT SHORTED TO VOLTAGE
2/1 O2 SENSOR HEATER OPERATION
EVAP SYSTEM OPERATION
TP SENSOR VOLTAGE GREATER THAN 0.92 OF A VOLT WITH THROTTLE CLOSED
TP SENSOR
FUEL FILTER/PRESSURE REGULATOR
MAP SENSOR
ECT SENSOR
ENGINE MECHANICAL CONDITION
PCM
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE -
DIAGNOSIS AND TESTING).
Diagnostic Test
1.GOOD TRIP EQUAL TO ZERO
NOTE: Check for contaminates that may have damaged the O2 Sensor: contaminated fuel, unapproved sil-
icone, oil and coolant.
Ignition on, engine not running.
With the scan tool, read DTCs and record the related Freeze Frame data.
NOTE: Any O2 Sensor, TPS, ECT, MAP, or EVAP DTCs must be repaired before continuing.
Is the Good Trip Counter displayed and equal to zero?
Ye s>>
Go To 2
No>>
Refer to the INTERMITTENT CONDITIONSymptom (Diagnostic Procedure).
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
9.ECT SENSOR OPERATION
NOTE: For this test to be valid, the thermostat must be operating correctly.
NOTE: This test works best if performed on a cold engine (cold soak)
Ignition on, engine not running.
With the scan tool, read the Engine Coolant Temperature Sensor value. If theenginewasallowedtositovernight
(cold soak), the temperature value should be a sensible value that is somewhere close to the ambient temperature.
NOTE: If engine coolant temperature is above 82°C (180°F), allow the engine to cool until 65°C (150°F) is
reached.
Start the Engine.
During engine warm-up, monitor the Engine Coolant Temperature value. Thetemp value change should be a
smooth transition from start up to normal operating temp 82°C (180°F). Thevalue should reach at least 82°C
(180°F).
Did the Engine Coolant Temperature value increase smoothly and reach at least 82°C?
Ye s>>
Go To 10
No>>
Replace the Engine Coolant Temperature Sensor.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
10.ENGINE MECHANICAL PROBLEM
Check for any of the following conditions/mechanical problems.
AIR INDUCTION SYSTEM - must be free from restrictions.
ENGINE VACUUM - must be at least 13 inches in neutral
ENGINE VALVE TIMING - must be within specifications
ENGINE COMPRESSION - must be within specifications
ENGINE EXHAUST SYSTEM - must be free of any restrictions or leaks.
ENGINE PCV SYSTEM - must flow freely
TORQUE CONVERTER STALL SPEED - must be within specifications
POWER BRAKE BOOSTER - no internal vacuum leaks
FUEL - must be free of contamination
FUEL INJECTOR - plugged or restricted injector; control wire not connectedtocorrectinjector
Are there any engine mechanical problems?
Ye s>>
Repair as necessary.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
No>>
Refer to the INTERMITTENT CONDITION Diagnostic Procedure.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
11 .O2 SENSOR
Disconnect the sensor harness connector of the O2 Sensor(s) that had a voltage value greater than 4.5 volts in the
previous step.
Ignition on, engine not running.
With the scan tool, monitor the O2 Sensor voltage reading(s).
Is the O2 Sensor voltage above 4.5 volts?
Ye s>>
Replace the O2 Sensor.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
No>>
Go To 12
When Monitored:
Ignition on.
Set Condition:
When the PCM recognizes the engine oil temperature sensor signal goes below a specific value.
Possible Causes
ENGINE OIL TEMP SENSOR
(G127) ENGINE OIL TEMP SENSOR SIGNAL CIRCUIT SHORTED TO GROUND
(G127) ENGINE OIL TEMP SENSOR CIRCUIT SHORTED TO THE (Z1) GROUND CIRCUIT
PCM
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE -
DIAGNOSIS AND TESTING)
1.EOT VOLTAGE BELOW 1.0 VOLT
Ignition on, engine not running.
With the scan tool, read DTCs and record the related Freeze Frame data.
With the scan tool, read the Engine Oil Temp Sensor voltage.
Is the EOT Sensor voltage below 1.0 volt?
Ye s>>
Go To 2
No>>
Refer to the INTERMITTENT CONDITIONSymptom (Diagnostic Procedure).
Perform POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
2.ENGINE OIL TEMP SENSOR
Turn the ignition off.
Disconnect the Engine Oil Temp harness connector.
Ignition on, engine not running.
With the scan tool, read Engine Oil Temp voltage.
Is the voltage above 1.0 volt?
Ye s>>
Replace the Engine Oil Temp Sensor.
Perform POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
No>>
Go To 3
3.(G127) EOT SENSOR SIGNAL CIRCUIT SHORTED TO GROUND
Turn the ignition off.
Disconnect the PCM harness connectors.
Measure the resistance between ground and the (G127) Engine Oil
Temp Sensor Signal circuit at the EOT Sensor harness connector.
Istheresistancebelow100ohms?
Ye s>>
Repair the short to ground in the (G127) Engine Oil Temp
Sensor Signal circuit.
Perform POWERTRAIN VERIFICATION TEST. (Refer to 9 -
ENGINE - STANDARD PROCEDURE)
No>>
Go To 4
When Monitored:
With battery voltage greater than 10.4 volts, the auto shutdown relay energized, injector pulse width less than
10ms, and engine speed less than 3000 rpm.
Set Condition:
This trouble code takes .64 to 10.0 seconds to set when no inductive kick is sensed .18ms after injector turn
off, and with no other injectors on.
Possible Causes
(K342) ASD RELAY OUTPUT CIRCUIT
(K11) INJECTOR CONTROL NO.1 CIRCUIT OPEN
(K11) INJECTOR CONTROL NO.1 CIRCUIT SHORTED TO GROUND
FUEL INJECTOR
PCM
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE -
DIAGNOSIS AND TESTING).
Diagnostic Test
1.ACTIVE DTC
Ignition on, engine not running.
With a scan tool, read DTCs.
Is the DTC active at this time?
Ye s>>
Go To 2
No>>
Refer to the INTERMITTENT CONDITION Diagnostic Procedure.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
2.(K342) ASD RELAY OUTPUT CIRCUIT
Turn the ignition off.
Disconnect the No.1 Fuel Injector harness connector.
Ignition on, engine not running.
With the scan tool, actuate the ASD Relay.
Using a 12-volt test light connected to ground, probe the (K342) ASD
Relay Output circuit in the Fuel Injector harness connector.
Does the test light illuminate brightly?
Ye s>>
Go To 3
No>>
Repair the excessive resistanceorshorttogroundinthe
(K342) ASD Relay Output circuit.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to
9 - ENGINE - STANDARD PROCEDURE)
When Monitored:
With battery voltage greater than 10.4 volts, the auto shutdown relay energized, injector pulse width less than
10ms, and engine speed less than 3000 rpm.
Set Condition:
This trouble code takes .64 to 10.0 seconds to set when no inductive kick is sensed .18ms after injector turn
off, and with no other injectors on.
Possible Causes
(K342) ASD RELAY OUTPUT CIRCUIT
(K12) INJECTOR CONTROL NO.2 CIRCUIT OPEN
(K12) INJECTOR CONTROL NO.2 CIRCUIT SHORTED TO GROUND
FUEL INJECTOR
PCM
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE -
DIAGNOSIS AND TESTING).
Diagnostic Test
1.ACTIVE DTC
Ignition on, engine not running.
With a scan tool, read DTCs.
Is the DTC active at this time?
Ye s>>
Go To 2
No>>
Refer to the INTERMITTENT CONDITION Diagnostic Procedure.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
2.(K342) ASD RELAY OUTPUT CIRCUIT
Turn the ignition off.
Disconnect the No.2 Fuel Injector harness connector.
Ignition on, engine not running.
With the scan tool, actuate the ASD Relay.
Using a 12-volt test light connected to ground, probe the (K342) ASD Relay Output circuit in the No.2 Fuel Injector
harness connector.
Does the test light illuminate brightly?
Ye s>>
Go To 3
No>>
Repair the excessive resistance or short to ground in the (K342) ASD Relay Output circuit.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
When Monitored:
With battery voltage greater than 10.4 volts, the auto shutdown relay energized, injector pulse width less than
10ms, and engine speed less than 3000 rpm.
Set Condition:
This trouble code takes .64 to 10.0 seconds to set when no inductive kick is sensed .18ms after injector turn
off, and with no other injectors on.
Possible Causes
(K342) ASD RELAY OUTPUT CIRCUIT
(K13) INJECTOR CONTROL NO.3 CIRCUIT OPEN
(K13) INJECTOR CONTROL NO.3 CIRCUIT SHORTED TO GROUND
FUEL INJECTOR
PCM
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE -
DIAGNOSIS AND TESTING).
Diagnostic Test
1.ACTIVE DTC
Ignition on, engine not running.
With a scan tool, read DTCs.
Is the DTC active at this time?
Ye s>>
Go To 2
No>>
Refer to the INTERMITTENT CONDITION Diagnostic Procedure.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
2.(K342) ASD RELAY OUTPUT CIRCUIT
Turn the ignition off.
Disconnect the No.3 Fuel Injector harness connector.
Ignition on, engine not running.
With the scan tool, actuate the ASD Relay.
Using a 12-volt test light connected to ground, probe the (K342) ASD
Relay Output circuit in the No.3 Fuel Injector harness connector.
Does the test light illuminate brightly?
Ye s>>
Go To 3
No>>
Repair the excessive resistanceorshorttogroundinthe
(K342) ASD Relay Output circuit.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to
9 - ENGINE - STANDARD PROCEDURE)