TEST ACTION APPLICABILITY
3 Turn Ignition On (Engine Off).
During the following voltage drop measurement, wiggle wires between O2S Connec-
tor and PCM Connector.
Using a voltmeter, backprobe O2S (Signal) Circuit between O2S Connector (O2S
Signal) and PCM Connector (O2S Signal).
While wiggling wires, is the voltage drop reading below 0.10 VDC?All
Ye s®Go To 4
No®Repair poor connection (high resistance) on O2S Signal Circuit.
Perform VERIFICATION TEST VER-5A3.
4 At this time the 1/2 O2S SLOW RESPONSE does not exist or is an intermittent
problem.
With the DRB, read the FREEZE FRAME DATA.
With this screen, attempt to duplicate the condition that has set this fault.
While using FREEZE FRAME DATA pay particular attention to the fault setting
conditions, such as speed, temp, load, and map vacuum.
Does the 1/2 O2S SLOW RESPONSE reoccur?All
Ye s®Go To 5
No®The 1/2 O2S SLOW RESPONSE no longer exists.
Perform VERIFICATION TEST VER-5A3.
5 The following are possible causes for O2 Sensor Slow Response: exhaust leak, fuel
contamination, O2 sensor failure, electrical wiring connectors, electrical mechanical,
and O2 heater failure.
Start the Engine.
NOTE: Check the exhaust for excessive smoke caused by oil or coolant
consumption.
Is there an oil or coolant consumption condition present?All
Ye s®Repair engine mechanical as necessary and replace O2 Sensor.
Perform VERIFICATION TEST VER-5A3.
No®Go To 6
6 The following are possible causes for O2 Sensor Slow Response: exhaust leak, fuel
contamination, O2 sensor failure, electrical wiring connectors, electrical mechanical,
and O2 heater failure.
Start the Engine.
Check the Exhaust System for leaks between the Engine and the catalyst.
Are there any leaks?All
Ye s®Repair or replace leaking Exhaust System as necessary.
Perform VERIFICATION TEST VER-5A3.
No®Go To 7
7 The following are possible causes for O2 Sensor Slow Response: exhaust leak, fuel
contamination, O2 sensor failure, electrical wiring connectors, electrical mechanical,
and O2 heater failure.
Turn Ignition On (Engine Off).
Using a voltmeter, backprobe O2S (Signal) Circuit between O2S Connector (O2S
Signal) and PCM Connector (O2S Signal).
Is the voltage drop reading below 0.10 VDC?All
Ye s®Go To 8
No®Repair poor connection (high resistance) on O2S Signal Circuit.
Perform VERIFICATION TEST VER-5A3.
69
DRIVEABILITY
P-0139 1/2 O2S SLOW RESPONSE ÐContinued
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Symptom:
P-0140 1/2 O2 SENSOR STAYS AT CENTER
When Monitored and Set Condition:
P-0140 1/2 O2 SENSOR STAYS AT CENTER
When Monitored: With the engine running for more than 2 minutes and engine
temperature greater than 76 degrees C (170 degrees F).
Set Condition: The Upstream Oxygen Sensor Signal voltage is between 0.35 volt and 0.55
volt for 1.5 minutes.
POSSIBLE CAUSES
O2 SENSOR 1/2 GROUND CIRCUIT OPEN
O2 SENSOR 1/2 SIGNAL CIRCUIT OPEN
1/2 O2 SENSOR WIRING HARN INTER DEFECT
1/2 O2 SENSOR WIRING HARN OBS DEFECT
O2 SENSOR 1/2 DEFECTIVE
PCM DEFECTIVE
TEST ACTION APPLICABILITY
1 Ignition Off
Start the engine and allow it to reach normal operating temperature.
With the DRB in actuator tests, set RPM to 1500.
In sensors, read the Downstream Oxygen Sensor Level.
Is the Downstream O2 Sensor Level switching?All
Ye s®Go To 2
No®Go To 4
2 Ignition Off
Start the engine and allow it to reach normal operating temperature.
Using the DRB, set the engine speed to 1500 RPM.
With the DRB, read the Downstream O2 Sensor state.
Wiggle Downstream O2 Sensor Connector and Harness.
While wiggling the Harness, monitor the DRB display.
At any time was the Downstream O2 Sensor state locked at center?All
Ye s®Repair the open Harness or Connector that caused the O2 Sensor
state to stay at center.
Perform Powertrain Verification Test VER-5A.
No®Go To 3
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DRIVEABILITY
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TEST ACTION APPLICABILITY
11 Check for any of the following conditions/mechanical problems.
ENGINE VACUUM Ð must be at least 13 inches in neutral
ENGINE VALVE TIMING Ð must be within specifications
ENGINE COMPRESSION Ð must be within specifications
ENGINE EXHAUST SYSTEM Ð must be free of any restrictions or leaks
ENGINE PVC SYSTEM Ð must flow freely
TORQUE CONVERTER STALL SPEED Ð must be within specifications
POWER BRAKE BOOSTER Ð no internal vacuum leaks
FUEL- must be free of contamination
FUEL INJECTOR Ð plugged or restricted injector; control wire not connected to
correct injector.
Are there any engine mechanical problems?All
Ye s®Repair as necessary.
Perform FUEL SYSTEM/MISFIRE MONITOR VERIFICATION
TEST
No®Go To 12
12 Turn ignition off.
Warning: The fuel system is under constant pressure (even with the engine
off). Before testing or servicing any fuel system hose, fitting or line, the fuel
system pressure must be released.
Disconnect the fuel supply line at the fuel rail.
Connect fuel line adapter #6539(5/169) or #6631 (3/89) to the disconnected fuel supply
line. Insert the other end of the adapter into a graduated container.
Caution: Do not operate the fuel pump for more than 7 seconds in the next
step. Fuel pump module reservoir may run empty and damage to the fuel
pump may result.
Specification: A good fuel pump will deliver at least 1/4 liter of fuel in 7
seconds.
With the DRB, actuate the ASD Fuel System test for 7 seconds.
Is the fuel pump capacity within specification?All
Ye s®Test Complete.
No®Check for a kinked/damaged fuel supply line between the fuel
tank and fuel rail. If OK, replace the fuel filter/pressure regulator.
Caution: Stop ALL Actuations.
13 The conditions required to set the DTC are no longer present.
With the DRB read and record the freeze frame data and the ªFuel System Similar
Conditions Windowº data.
Utilize the data and try to duplicate the operating conditions at which the DTC was
set. Pay particular attention to the ECT and RPM for added diagnostics.
Note: Refer to any TSB's that may apply to the symptom.
Test Complete
Repair
Test Complete.
78
DRIVEABILITY
P-0171±1/1 FUEL SYSTEM LEAN ÐContinued
ProCarManuals.com
TEST ACTION APPLICABILITY
8 Turn ignition off.
Warning: The fuel system is under a constant pressure (even with the engine
off). Before testing or servicing any fuel system hose, fitting or line, the fuel
system pressure must be released.
Remove the pressure test port cap at the fuel rail test port. Connect a fuel pressure
gauge to the test port pressure fitting on the fuel rail.
Ignition on. With the DRB, actuate the ASD Fuel System test and observe the fuel
pressure gauge.
Note: Fuel pressure specification is 49.2 psi +/þ 5 psi.
Choose a conclusion that best matches your fuel pressure reading.All
Below Specification
Go To 9
Within Specification
Go To 13
Above Specification
Replace the fuel filter/pressure regulator.
Caution: Stop ALL Actuations.
9 Check for any of the following conditions/mechanical problems.
ENGINE VACUUM Ð must be at least 13 inches in neutral
ENGINE VALVE TIMING Ð must be within specifications
ENGINE COMPRESSION Ð must be within specifications
ENGINE EXHAUST SYSTEM Ð must be free of any restrictions or leaks.
ENGINE PVC SYSTEM Ð must flow freely
TORQUE CONVERTER STALL SPEED Ð must be within specifications
POWER BRAKE BOOSTER Ð no internal vacuum leaks
FUEL - must be free of contamination
FUEL INJECTOR Ð plugged or restricted injector; control wire not connected to
correct injector
Are there any engine mechanical problems?All
Ye s®Repair as necessary.
Perform FUEL SYSTEM/MISFIRE MONITOR VERIFICATION
TEST
No®Go To 10
10 Turn ignition off.
Warning: The fuel system is under a constant pressure (even with the engine
off). Before testing or servicing any fuel system hose, fitting or line, the fuel
system pressure must be released.
Raise vehicle on hoist, and disconnect the fuel pressure line at the fuel pump module.
Install special 5/169fuel line adapter tool #6539 between disconnected fuel line and
the fuel pump module.
Attach a fuel pressure test gauge to the ªT'' fitting on tool #6539.
Ignition on. With the DRB, actuate the ASD Fuel System test and observe the fuel
pressure gauge.
Note: Fuel pressure specification is 49.2 psi +/- 5 psi.
Is the fuel pressure within specification now?All
Ye s®Repair the restriction in the chassis fuel supply line between the
fuel tank and fuel rail.
No®Go to 11
Caution: Stop ALL Actuations.
81
P0172 -1/1 FUEL SYSTEM RICH ÐContinued
ProCarManuals.com
TEST ACTION APPLICABILITY
11Warning: The fuel system is under a constant pressure (even with the engine
off). Before testing or servicing any fuel system hose, fitting or line, the fuel
system pressure must be released.
Remove the Fuel Pump Module and inspect the Fuel Inlet Strainer.
Is the Fuel Inlet Strainer plugged?All
Ye s®Replace the Fuel Inlet Strainer.
No®Go To 12
12 If there are no potential causes remaining, the Fuel Pump Module is assumed to be
defective.
View repair options.All
Repair
Replace the Fuel Pump Module
13 Check for any of the following conditions/mechanical problems.
ENGINE VACUUM Ð must be at least 13 inches in neutral
ENGINE VALVE TIMING Ð must be within specifications
ENGINE COMPRESSION Ð must be within specifications
ENGINE EXHAUST SYSTEM Ð must be free of any restrictions or leaks.
ENGINE PVC SYSTEM Ð must flow freely
TORQUE CONVERTER STALL SPEED Ð must be within specifications
POWER BRAKE BOOSTER Ð no internal vacuum leaks
FUEL - must be free of contamination
FUEL INJECTOR Ð plugged or restricted injector; control wire not connected to
correct injector
Are there any engine mechanical problems?All
Ye s®Repair as necessary.
Perform FUEL SYSTEM/MISFIRE MONITOR VERIFICATION
TEST
No®Test Complete.
14 The conditions required to set the DTC are no longer present.
With the DRB read and record the freeze frame data and the ªFuel System Similar
Conditions Window'' data.
Utilize the data and try to duplicate the operating conditions at which the DTC was
set. Pay particular attention to the ECT and RPM for added diagnostics.
Note: Refer to any TSB's that may apply to the symptom.
Test Complete
Repair
Test Complete.
82
P0172 -1/1 FUEL SYSTEM RICH ÐContinued
ProCarManuals.com
Symptom:start here
P-0201 INJECTOR #1 CONTROL CIRCUIT
When Monitored and Set Condition:
P-0201 INJECTOR #1 CONTROL CIRCUIT
When Monitored: With battery voltage greater than 12 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
ASD RELAY OUTPUT CIRCUIT OPEN
INJECTOR DEFECTIVE
INJECTOR #1 DRIVER CIRCUIT OPEN
INJECTOR #1 DRIVER CIRCUIT SHORTED TO GROUND
POWERTRAIN CONTROL MODULE DEFECTIVE
INJECTOR #1 DRIVER CIRCUIT SHORT TO GROUND
INJECTOR #1 DRIVER CIRCUIT SHORT TO GROUND (PCM)
TEST ACTION APPLICABILITY
1 Ignition Off
Start engine, let idle for at least 20 seconds.
Key on, engine off.
With the DRB, read Trouble Codes.
Is the Global Good Trip counter displayed and equal to zero?All
Ye s®Go To 2
No®Go To 7
2 Ignition Off
Disconnect the Injector #1 Connector.
Note: Check connectors - Clean/repair as necessary.
Using an Ohmmeter, measure resistance of Injector #1.
Is the resistance between 10.0 and 16.0 ohms?All
Ye s®Go To 3
No®Replace the Fuel Injector.
Perform Powertrain Verification Test VER-5A.
83
DRIVEABILITY
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Symptom:
P-0202 INJECTOR #2 CONTROL CIRCUIT
When Monitored and Set Condition:
P-0202 INJECTOR #2 CONTROL CIRCUIT
When Monitored: With battery voltage greater than 12 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
ASD RELAY OUTPUT CIRCUIT OPEN
INJECTOR DEFECTIVE
INJECTOR #2 DRIVER CIRCUIT OPEN
INJECTOR #2 DRIVER CIRCUIT SHORTED TO GROUND
PCM DEFECTIVE
TEST ACTION APPLICABILITY
1 Ignition Off
Start engine, let idle for at least 20 seconds.
Key on, engine off.
With the DRB, read Trouble Codes.
Is the Global Good Trip counter displayed and equal to zero?All
Ye s®Go To 2
No®Go To 7
2 Ignition Off
Note: It may be necessary to remove the Intake Plenum in the following
steps.
Disconnect the Injector #2 Connector.
Note: Check connectors - Clean/repair as necessary.
Using an Ohmmeter, measure resistance of Injector #2.
Is the resistance between 10.0 and 16.0 ohms?All
Ye s®Go To 3
No®Replace the Fuel Injector.
Perform Powertrain Verification Test VER-5A.
86
DRIVEABILITY
ProCarManuals.com
Symptom:
P-0203 INJECTOR #3 CONTROL CIRCUIT
When Monitored and Set Condition:
P-0203 INJECTOR #3 CONTROL CIRCUIT
When Monitored: With battery voltage greater than 12 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
ASD RELAY OUTPUT CIRCUIT OPEN
FUEL INJECTOR #3 DEFECTIVE
INJECTOR #3 DRIVER CIRCUIT OPEN
INJECTOR #3 DRIVER CIRCUIT SHORTED TO GROUND
PCM DEFECTIVE
TEST ACTION APPLICABILITY
1 Ignition Off
Start engine, let idle for at least 20 seconds.
Key on, engine off.
With the DRB, read Trouble Codes.
Is the Global Good Trip counter displayed and equal to zero?All
Ye s®Go To 2
No®Go To 7
2 Ignition Off
Note: It may be necessary to remove the Intake Plenum in the following
steps.
Disconnect the Injector #3 Connector.
Note: Check connectors - Clear/repair as necessary.
Using an Ohmmeter, measure the resistance of Injector #3.
Is the resistance between 10.0 and 16.0 ohms?All
Ye s®Go To 3
No®Replace the Fuel Injector.
Perform Powertrain Verification Test VER-5A.
89
DRIVEABILITY
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