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)
P0300-MULTIPLE CYLINDER MISFIRE
For a complete wiring diagramRefer to Section 8W.
When Monitored:
Any time the engine is running, and the adaptive numerator has been successfully updated.
Set Condition:
When more than a 2% (2.5% LEV) misfire rate is measured during two trips. Above 3000 RPM 1 trip less than
3000 RPM 2 trip. Three good trips to turn off the MIL.
Possible Causes
(K342) ASD RELAY OUTPUT CIRCUIT
INJECTOR CONTROL CIRCUIT
COIL CONTROL CIRCUIT
IGNITION WIRE
SPARK PLUG
IGNITION COIL
FUEL PUMP INLET STRAINER PLUGGED
RESTRICTED FUEL SUPPLY LINE
FUEL PUMP MODULE
FUEL PRESSURE LEAK DOWN
FUEL INJECTOR
ENGINE MECHANICAL
PCM
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE -
DIAGNOSIS AND TESTING).
Diagnostic Test
1.CYLINDER MIS-FIRE CONDITION ACTIVE
NOTE: Check for any TSB’s that apply to a Misfire condition. Review the vehicle repair history for any mis-
fire condition repairs that have been performed.
Star the engine.
Observe the WHICH CYLINDER IS MISFIRING screen for at least one minute on the scan tool.
Is there a misfire present?
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.VISUAL INSPECTION
NOTE: Anything that affects the speed of the crankshaft can cause a misfireDTC.
NOTE: When a Misfire is detected for a particular cylinder, the PCM will shut down that cylinders Injector
Control circuit.
- Visually inspect the engine for any of the following conditions.
- Worn serpentine belt
- Binding Engine-Driven accessories: A/C Compressor, P/S Pump, Water pump.
- Misalignment of the Water pump, P/S Pump and A/C Compressor pulleys
- Corroded PCM power and ground circuits.
- Improper CKP, CMP, MAP, and TP Sensor mounting
- Poor connector/terminal to component connection. i.e., CKP sensor, Fuel Injector, Ign coil, etc.
11 .INJECTOR CONTROL CIRCUIT
Turn the ignition off.
Disconnect the Fuel Injector harness connector.
Disconnect the PCM harness connectors.
CAUTION: Do not probe the PCM harness connectors. Probing the PCM harness connectors will damage
the PCM terminals resulting in poor terminal to pin connection. Install Miller Special Tool 8815 to perform
diagnosis.
Check the Injector Control circuit for an open, short to ground, and short to voltage.
Was a problem found with the Injector Control circuit?
Ye s>>
Repair the excessive resistance or short in the Injector Control circuit.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
No>>
Go To 17
12.FUEL SUPPLY LINE RESTRICTED
Turn the ignition off.
WARNING: The fuel system is under a constant pressure (even with the engineoff). Before testing or ser-
vicing any fuel system hose, fitting or line, the fuel system pressure mustbe released. Failure to follow
these instructions can result in personal injury or death.
Raise vehicle on hoist, and disconnect the fuel pressure line at the fuel pump module.
Install special tool 6539 (5/16
) 6631(3/8) fuel line adapter and the fuel pressure gauge between the fuel supply line
and the fuel pump module.
Ignition on, engine not running.
With the scan tool, actuate the ASD FuelSystem test and observe the fuel pressure gauge.
NOTE: Fuel pressure specification is 407 KPa +/- 34 KPa (59 psi +/- 5 psi).
Is the fuel pressure within specification?
Ye s>>
Repair or replace fuel supply line as necessary.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
No>>
Go To 13
13.FUEL PUMP INLET STRAINER
Turn the ignition off.
WARNING: The fuel system is under a constant pressure (even with the engineoff). Before testing or ser-
vicing any fuel system hose, fitting or line, the fuel system pressure mustbe released. Failure to follow
these instructions can result in personal injury or death.
Remove the Fuel Pump Module and inspect the Fuel Inlet Strainer.
Is the Fuel Inlet Strainer plugged?
Ye s>>
Replace the Fuel Pump Inlet Strainer.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
No>>
Before continuing, check the Fuel Pump Module harness connector terminals for corrosion, damage, or
terminal push out. Make sure the ground circuit is functional. Repair as necessary. Replace the Fuel
Pump Module.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
14.IGNITION WIRE
NOTE: If the vehicle being tested does not have an ignition wire answer YES to this test and continue.
Turn the ignition off.
Remove the ignition wire.
Measure the resistance of the ignition wire.
Is the resistance below 10K ohms?
Ye s>>
Go To 14
No>>
Replace the Ignition Wire.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
15.IGNITION COIL
Disconnect the Ignition Coil harness connector.
RemovetheFuelPumpfuseorASDfuse.
Using a 12-volt test light connected to 12-volts, probe the Ignition Coil Control circuit.
Crank the engine for 5 seconds while observing the test light.
Does the test light brightly blink/flicker?
Ye s>>
Replace the Ignition Coil.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
No>>
Go To 15
16.COIL CONTROL CIRCUIT
Turn the ignition off.
Disconnect the Ignition Coil harness connector.
Disconnect the PCM harness connectors.
CAUTION: Do not probe the PCM harness connectors. Probing the PCM harness connectors will damage
the PCM terminals resulting in poor terminal to pin connection. Install Miller Special Tool 8815 to perform
diagnosis.
Check the Coil Control circuit for an open, short to ground, and short to voltage.
Was a problem found with the Coil Control circuit?
Ye s>>
Repair the Coil Control circuit.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
No>>
Go To 17
17.PCM
NOTE: Before continuing, check the PCM harness connector terminals for corrosion, damage, or terminal
push out. Repair as necessary.
Using the schematics as a guide, inspect the wire harness and connectors. Pay particular attention to all Power and
Ground circuits.
Were there any problems found?
Ye s>>
Repair as necessary.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
No>>
Replace and program the Powertrain Control Module per Service Information.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
When Monitored:
Any time the engine is running, and the adaptive numerator has been successfully updated.
Set Condition:
When more than a 1% misfire rate is measured during two trips, or with a 6% to 30% misfire rate during one
trip.
Possible Causes
(K342) ASD OUTPUT CIRCUIT
(K11) INJECTOR CONTROL CIRCUIT
(K19) COIL CONTROL CIRCUIT
IGNITION WIRE
SPARK PLUG
IGNITION COIL
FUEL PUMP INLET STRAINER PLUGGED
RESTRICTED FUEL SUPPLY LINE
FUEL PUMP MODULE
FUEL PRESSURE LEAK DOWN
FUEL INJECTOR
ENGINE MECHANICAL
PCM
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE -
DIAGNOSIS AND TESTING).
Diagnostic Test
1.CYLINDER MIS-FIRE CONDITION ACTIVE
Engine running.
Observe the WHICH CYLINDER IS MISFIRING screen for at least one minute on the scan tool.
Isthereamisfirepresentatthistime?
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.VISUAL INSPECTION
NOTE: Anything that affects the speed of the crankshaft can cause a misfireDTC.
NOTE: When a Misfire is detected for a particular cylinder, the PCM will shut down that cylinders Injector
Control circuit.
- Visually inspect the engine for any of the following conditions.
- Worn serpentine belt
- Binding Engine-Driven accessories: A/C Compressor, P/S Pump, Water pump.
- Misalignment of the Water pump, P/S Pump and A/C Compressor pulleys
- Corroded PCM power and ground circuits.
- Improper CKP, CMP, MAP, and TP Sensor mounting
- Poor connector/terminal to component connection. i.e., CKP sensor, Fuel Injector, Ign coil, etc.
- Vacuum leaks
- Restricted Air Induction system or Exhaust system.
12.FUEL SUPPLY LINE RESTRICTED
Turn the ignition off.
WARNING: The fuel system is under a constant pressure (even with the engineoff). Before testing or ser-
vicing any fuel system hose, fitting or line, the fuel system pressure mustbe released. Failure to follow
these instructions can result in personal injury or death.
Raise vehicle on hoist, and disconnect the fuel pressure line at the fuel pump module.
Install special tool 6539 (5/16
) 6631(3/8) fuel line adapter and the fuel pressure gauge between the fuel supply line
and the fuel pump module.
Ignition on, engine not running.
With the scan tool, actuate the ASD FuelSystem test and observe the fuel pressure gauge.
NOTE: Fuel pressure specification is 379 KPa +/- 14 KPa (55 psi +/- 2 psi).
Is the fuel pressure within specification?
Ye s>>
Repair or replace fuel supply line as necessary.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
No>>
Go To 13
13.FUEL PUMP INLET STRAINER
Turn the ignition off.
WARNING: The fuel system is under a constant pressure (even with the engineoff). Before testing or ser-
vicing any fuel system hose, fitting or line, the fuel system pressure mustbe released. Failure to follow
these instructions can result in personal injury or death.
Remove the Fuel Pump Module and inspect the Fuel Inlet Strainer.
Is the Fuel Inlet Strainer plugged?
Ye s>>
Replace the Fuel Pump Inlet Strainer.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
No>>
Before continuing, check the Fuel Pump Module harness connector terminals for corrosion, damage, or
terminal push out. Make sure the ground circuit is functional. Repair as necessary. Replace the Fuel
Pump Module.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
14.IGNITION WIRE
NOTE: If the vehicle being tested does not have an ignition wire answer YES to this test and continue.
Turn the ignition off.
Remove the ignition wire.
Measure the resistance of the ignition wire.
Is the resistance below 10K ohms?
Ye s>>
Go To 15
No>>
Replace the Ignition Wire.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
15.IGNITION COIL
Disconnect the Ignition Coil harness connector.
Remove the Fuel Pump Relay.
Using a 12-volt test light connected to 12-volts, probe the (K19) Ignition
Coil Control No.1 circuit.
Crank the engine for 5 seconds while observing the test light.
NOTE: The primary resistance of the 8.3L Ignition coil is 0.53 to
0.65 of an ohm at 77°F (25°C).
Does the test light brightly blink/flicker?
Ye s>>
Replace the Ignition Coil.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to
9 - ENGINE - STANDARD PROCEDURE)
No>>
Go To 16
16.(K19) IGNITION COIL CONTROL NO.1 CIRCUIT
Turn the ignition off.
Disconnect the C1 PCM harness connector.
Check the (K19) Ignition Coil Control No.1 circuit for an open or short to
ground.
Was a problem found with the Coil Control circuit?
Ye s>>
Repair the (K19) Ignition Coil Control No.1 circuit.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to
9 - ENGINE - STANDARD PROCEDURE)
No>>
Go To 17
When Monitored:
Any time the engine is running, and the adaptive numerator has been successfully updated.
Set Condition:
When more than a 1% misfire rate is measured during two trips, or with a 6% to 30% misfire rate during one
trip.
Possible Causes
(K342) ASD RELAY OUTPUT CIRCUIT
(K12) INJECTOR CONTROL CIRCUIT
(K134) COIL CONTROL CIRCUIT
IGNITION WIRE
SPARK PLUG
IGNITION COIL
FUEL PUMP INLET STRAINER PLUGGED
RESTRICTED FUEL SUPPLY LINE
FUEL PUMP MODULE
FUEL PRESSURE LEAK DOWN
FUEL INJECTOR
ENGINE MECHANICAL
PCM
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE -
DIAGNOSIS AND TESTING).
Diagnostic Test
1.CYLINDER MIS-FIRE CONDITION ACTIVE
Engine running.
Observe the WHICH CYLINDER IS MISFIRING screen for at least one minute on the scan tool.
Isthereamisfirepresentatthistime?
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.VISUAL INSPECTION
NOTE: Anything that affects the speed of the crankshaft can cause a misfireDTC.
NOTE: When a Misfire is detected for a particular cylinder, the PCM will shut down that cylinders Injector
Control circuit.
- Visually inspect the engine for any of the following conditions.
- Worn serpentine belt
- Binding Engine-Driven accessories: A/C Compressor, P/S Pump, Water pump.
- Misalignment of the Water pump, P/S Pump and A/C Compressor pulleys
- Corroded PCM power and ground circuits.
- Improper CKP, CMP, MAP, and TP Sensor mounting
- Poor connector/terminal to component connection. i.e., CKP sensor, Fuel Injector, Ign coil, etc.
- Vacuum leaks
- Restricted Air Induction system or Exhaust system.