
TEST ACTION APPLICABILITY
5NOTE: If the ECM detects and stores a DTC, the ECM also stores the
engine/vehicle operating conditions under which the DTC was set. Some of
these conditions are displayed on the DRB IIItat the same time the DTC is
displayed.
NOTE: Before erasing stored DTCs, record these conditions. Attempting to
duplicate these conditions may assist when checking for an active DTC.
NOTE: Refer to the Service Information and perform the Air Bleed Proce-
dure before continuing diagnosis.
Turn the ignition on.
With the DRBIIIt, erase the ECM DTCs.
Start and idle the engine while monitoring for ECM DTC's.
If the DTC does not reset at idle condition, test drive the vehicle under various load
and speed conditions to attempt to duplicate the fault.
NOTE: Driving the vehicle up and down steep hills or rapid cornering with
a low fuel level can cause this DTC to set. Verify with customer if Low Fuel
Light was illuminated when fault occurred.
With the DRBIIIt, read the ECM DTCs.
Does the DRBIIItdisplay this DTC?All
Ye s!Go To 6
No!Go To 16
6 Start the engine.
With the DRBIIItin Sensors, compare the Fuel Pressure Setpoint with the Actual
Fuel Pressure readings.
NOTE: If there is air in the fuel system, the Actual Fuel Pressure will
oscillate above and below the Fuel Pressure Setpoint.
Does Actual Fuel Pressure oscillate above and below the Fuel Pressure Setpoint?All
Ye s!Refer to the Service Information to purge air from the fuel system.
Perform ROAD TEST VERIFICATION - VER-2.
No!Go To 7
7 Start the engine.
With the DRBIIItin Sensors, compare the Fuel Pressure Setpoint with the Actual
Fuel Pressure readings.
NOTE: A sticking Fuel Pressure Solenoid is indicated by Actual Fuel
Pressure gradually dropping below the Fuel Pressure Setpoint then sud-
denly increasing (spiking) above the Fuel Pressure Setpoint.
Does Actual Fuel Pressure gradually decrease then suddenly increase (spike) above
the Fuel PressureAll
Ye s!Replace the Fuel Pressure Solenoid in accordance with the
Service Information.
Perform ROAD TEST VERIFICATION - VER-2.
No!Go To 8
120
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P2015-FUEL RAIL PRESSURE MALFUNCTION MAXIMUM FUEL FLOW
EXCEEDED Ð
Continued

TEST ACTION APPLICABILITY
8 Refer to the appropriate Service Information and refer to Diagnosis and Testing Fuel
Delivery System table.
NOTE: The following is a list of problems that can cause fuel pressure to
deviate from specification: restricted fuel filter or fuel lines, failed fuel
pressure solenoid, failed fuel lift pump, failed fuel sending unit, contami-
nated fuel, faulty injector.
Were there any problems with the Fuel Delivery System?All
Ye s!Repair as necessary in accordance with the Service Information.
Perform ROAD TEST VERIFICATION - VER-2.
No!Go To 9
9 Refer to each of the following symptoms in the Driveability category.
CHECKING THE FUEL PRESSURE SOLENOID CIRCUITS
CHECKING THE FUEL QUANTITY SOLENOID CIRCUITS
CHECKING THE FUEL PRESSURE SENSOR CIRCUITS
Were any problems found?All
Ye s!Repair as necessary.
Perform ROAD TEST VERIFICATION - VER-2.
No!Go To 10
10NOTE: An injector that sticks open can cause this DTC. A sticking injector
will cause the engine to misfire and emit excessive black smoke from the
exhaust system.
Refer to the Service Information and perform the Fuel Injector Leak Quantity Test.
Were any problems found?All
Ye s!Using the Service Information, remove and inspect the Fuel
Injectors for signs of damage or debris that may cause the injector
to stick. Sticking injectors may cause the combustion chamber to
become black and oil soaked. Replace Injector(s) as necessary.
Perform ROAD TEST VERIFICATION - VER-2.
No!Go To 11
11 With the DRBIIIt, select System Test, Smooth Eng Run Check, then Correction
Quantity Check.
Perform this test at Idle, 2000 rpm and 3000 rpm.
NOTE: Readings per cylinder should be below 0.00450 mm
3/stroke for each
cylinder at each engine speed.
Did any of the cylinders exceed 0.00450 mm
3/stroke during this test?All
Ye s!Replace Fuel Injector of the cylinder(s) that had readings above
0.00450 mm
3/stroke.
Perform ROAD TEST VERIFICATION - VER-2.
No!Go To 12
12 With the DRBIIIt, select System Test, Smooth Eng Run Check, then Cylinder Speed
Check.
NOTE: Readings for all cylinders should be close to each other. Look for one
or two cylinders to differ high or low from the other cylinders.
Did any of the cylinders differ significantly from the majority of the other cylinders?All
Ye s!Replace Fuel Injector of the cylinder(s) that had readings signif-
icantly above or below the other fuel injectors.
Perform ROAD TEST VERIFICATION - VER-2.
No!Go To 13
121
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P2015-FUEL RAIL PRESSURE MALFUNCTION MAXIMUM FUEL FLOW
EXCEEDED Ð
Continued

TEST ACTION APPLICABILITY
17 Refer to the appropriate Service Information and refer to Diagnosis and Testing Fuel
Delivery System table.
NOTE: The following is a list of problems that can cause fuel pressure to
deviate from specification: restricted fuel filter or fuel lines, failed fuel
pressure solenoid, air in fuel system, failed fuel sending unit, contaminated
fuel, faulty injector.
Were there any problems with the Fuel Delivery System?All
Ye s!Repair as necessary in accordance with the Service Information.
Perform ROAD TEST VERIFICATION - VER-2.
No!Go To 18
18 Refer to each of the following symptoms in the Driveability category.
CHECKING THE FUEL PRESSURE SOLENOID CIRCUITS
CHECKING THE FUEL QUANTITY SOLENOID CIRCUITS
CHECKING THE FUEL PRESSURE SENSOR CIRCUITS
Were any problems found?All
Ye s!Repair as necessary.
Perform ROAD TEST VERIFICATION - VER-2.
No!Go To 19
19NOTE: An injector that sticks open can cause this DTC. A sticking injector
will cause the engine to misfire and emit excessive black smoke from the
exhaust system.
Refer to the Service Information and perform the Fuel Injector Leak Quantity during
engine cranking test.
Were any problems found?All
Ye s!Using the Service Information, remove and inspect the Fuel
Injectors for signs of damage or debris that may cause the injector
to stick. Sticking injectors may cause the combustion chamber to
become black and oil soaked. Replace Injector(s) as necessary.
Perform ROAD TEST VERIFICATION - VER-2.
No!Go To 20
20 Turn the ignition off.
Replace the Fuel Pressure Solenoid in accordance with the Service Information.
Turn the ignition on.
With the DRBIIIt, erase the ECM DTCs.
Attempt to start and test drive the vehicle.
With the DRBIIIt, read the ECM DTCs.
Did this DTC set again?All
Ye s!Go To 21
No!Test Complete.
123
DRIVEABILITY - DIESEL
P2015-FUEL RAIL PRESSURE MALFUNCTION MAXIMUM FUEL FLOW
EXCEEDED Ð
Continued

Symptom:
P2025-INTAKE PRESSURE SENSOR PLAUSIBILITY
When Monitored and Set Condition:
P2025-INTAKE PRESSURE SENSOR PLAUSIBILITY
When Monitored: With the ignition on.
Set Condition: The Intake Pressure Sensor signal does not agree with the Atmospheric
Pressure Sensor signal in the ECM.
POSSIBLE CAUSES
AIR FILTER
AIR RESTRICTION
INTERMITTENT CONDITION
HIGH RESISTANCE IN THE INTAKE PRESSURE SENSOR SIGNAL CIRCUIT
HIGH RESISTANCE IN THE INTAKE PRESSURE SENSOR GROUND CIRCUIT
HIGH RESISTANCE IN THE INTAKE PRESSURE SENSOR 5-VOLT SUPPLY CIRCUIT
ENGINE CONTROL MODULE
TEST ACTION APPLICABILITY
1NOTE: If DTC P1611, P2306 or P2332 is present with this DTC, diagnose
DTCs P1611, P2306 or P2332 before diagnosing this DTC.
NOTE: If the ECM detects and stores a DTC, the ECM also stores the
engine/vehicle operating conditions under which the DTC was set. Some of
these conditions are displayed on the DRB at the same time the DTC is
displayed.
NOTE: Before erasing stored DTCs, record these conditions. Attempting to
duplicate these conditions may assist when checking for an active DTC.
Turn the ignition on.
With the DRB, erase ECM DTCs.
Turn the ignition off, wait 30 seconds.
Test drive the vehicle.
With the DRB, read ECM DTCs.
Did this DTC set again?All
Ye s!Go To 2
No!Go To 7
2 Turn the ignition off.
Remove and inspect the Air Filter for soiling or excessive dirt and debris which may
cause air flow restriction.
Were any of these problems found?All
Ye s!Replace the Air Filter element.
Perform ROAD TEST VERIFICATION - VER-2.
No!Go To 3
125
DRIVEABILITY - DIESEL

Symptom List:
P2025-INTAKE PRESSURE SENSOR SIGNAL VOLTAGE TOO HIGH
P2030-INTAKE PRESSURE SENSOR CIRCUIT FAULT
P2030-INTAKE PRESSURE SENSOR OPEN CIRCUIT
P2030-INTAKE PRESSURE SENSOR SIGNAL VOLTAGE TOO HIGH
Test Note: All symptoms listed above are diagnosed using the same tests.
The title for the tests will be P2025-INTAKE PRESSURE
SENSOR SIGNAL VOLTAGE TOO HIGH.
POSSIBLE CAUSES
INTERMITTENT CONDITION
INTAKE PRESSURE SENSOR GROUND CIRCUIT SHORTED TO VOLTAGE
INTAKE PRESSURE SENSOR SIGNAL CIRCUIT SHORTED TO VOLTAGE
INTAKE PRESSURE SENSOR GROUND CIRCUIT OPEN
INTAKE PRESSURE SENSOR
ENGINE CONTROL MODULE (INTERNAL)
ENGINE CONTROL MODULE (SENSOR SIGNAL SHORTED TO VOLTAGE)
TEST ACTION APPLICABILITY
1NOTE: If the ECM detects and stores a DTC, the ECM also stores the
engine/vehicle operating conditions under which the DTC was set. Some of
these conditions are displayed on the DRB at the same time the DTC is
displayed.
NOTE: Before erasing stored DTCs, record these conditions. Attempting to
duplicate these conditions may assist when checking for an active DTC.
NOTE: Ensure all turbocharger inlet and outlet tubes are connected prop-
erly, without damage and restriction before continuing with this test. Also
ensure the Boost Pressure Servo Motor and Servo Motor rod are attached
and functioning properly.
Turn the ignition on.
With the DRB, erase ECM DTCs.
Cycle the ignition key on and off several times, leaving the key on for at least 10
seconds at a time.
With the DRB, read ECM DTCs.
Did this DTC set again?All
Ye s!Go To 2
No!Go To 7
128
DRIVEABILITY - DIESEL

TEST ACTION APPLICABILITY
2 Turn the ignition off.
Disconnect the Intake Pressure Sensor harness connector.
Disconnect the ECM harness connectors.
Turn the ignition on.
Measure the voltage between ground and the Intake Pressure Sensor Signal circuit.
Is the voltage above 1.0 volt?All
Ye s!Go To 3
No!Go To 4
3 Turn the ignition off.
Disconnect the Intake Pressure Sensor harness connector.
Disconnect the ECM harness connectors.
Remove the Engine Control Relay.
Connect a jumper wire between cavity 30 and cavity 87 of the Engine Control Relay
connector.
Turn the ignition on.
Measure the voltage between ground and the Intake Pressure Sensor Signal circuit.
Is the voltage above 1.0 volt?All
Ye s!Repair the Intake Pressure Sensor Signal circuit for a short to
voltage.
Perform ROAD TEST VERIFICATION - VER-2.
No!Replace and program the Engine Control Module in accordance
with the Service Information.
Perform ROAD TEST VERIFICATION - VER-2.
4 Turn the ignition off.
Disconnect the Intake Pressure Sensor harness connector.
Disconnect the ECM harness connectors.
Remove the Engine Control Relay.
Connect a jumper wire between cavity 30 and cavity 87 of the Engine Control Relay
connector.
Turn the ignition on.
Measure the voltage between ground and the Intake Pressure Sensor Ground circuit.
Is the voltage above 1.0 volt?All
Ye s!Repair the Intake Pressure Sensor Ground circuit for a short to
voltage. Note: The ECM will need to be checked for proper
operation before the repair is completed. A short to voltage on a
ground circuit can damage the ECM.
Perform ROAD TEST VERIFICATION - VER-2.
No!Go To 5
5 Turn the ignition off.
Disconnect the Intake Pressure Sensor harness connector.
Disconnect the ECM harness connectors.
Measure the resistance of the Sensor Ground circuit.
Is the resistance below 10.0 ohms?All
Ye s!Go To 6
No!Repair the Intake Pressure Sensor Ground circuit for an open.
Perform ROAD TEST VERIFICATION - VER-2.
129
DRIVEABILITY - DIESEL
P2025-INTAKE PRESSURE SENSOR SIGNAL VOLTAGE TOO HIGH Ð
Continued

Symptom List:
P2025-INTAKE PRESSURE SENSOR SIGNAL VOLTAGE TOO LOW
P2030-INTAKE PRESSURE SENSOR SIGNAL VOLTAGE TOO LOW
Test Note: All symptoms listed above are diagnosed using the same tests.
The title for the tests will be P2025-INTAKE PRESSURE
SENSOR SIGNAL VOLTAGE TOO LOW.
POSSIBLE CAUSES
INTERMITTENT CONDITION
INTAKE PRESSURE SENSOR 5 VOLT SUPPLY
INTAKE PRESSURE SENSOR
INTAKE PRESSURE SENSOR SIGNAL CIRCUIT SHORTED TO GROUND
INTAKE PRESSURE SENSOR SIGNAL AND GROUND CIRCUITS SHORTED TOGETHER
ENGINE CONTROL MODULE
INTAKE PRESSURE SENSOR SIGNAL CIRCUIT OPEN
TEST ACTION APPLICABILITY
1NOTE: If the ECM detects and stores a DTC, the ECM also stores the
engine/vehicle operating conditions under which the DTC was set. Some of
these conditions are displayed on the DRB at the same time the DTC is
displayed.
NOTE: Before erasing stored DTCs, record these conditions. Attempting to
duplicate these conditions may assist when checking for an active DTC.
NOTE: Ensure all turbocharger inlet and outlet tubes are connected prop-
erly, without damage and restriction before continuing with this test. Also
ensure the Boost Pressure Servo Motor and Servo Motor rod are attached
and functioning properly.
Turn the ignition on.
With the DRB, erase ECM DTCs.
Cycle the ignition key on and off several times, leaving the key on for at least 10
seconds at a time.
With the DRB, read ECM DTCs.
Did this DTC set again?All
Ye s!Go To 2
No!Go To 7
2 Turn the ignition off.
Disconnect the Intake Pressure Sensor harness connector.
Turn the ignition on.
Measure the voltage between ground and the Intake Pressure Sensor 5 Volt Supply
circuit.
Is the voltage above 4.8 volts?All
Ye s!Go To 3
No!Repair the Intake Pressure Sensor 5 Volt Supply circuit for an
open.
Perform ROAD TEST VERIFICATION - VER-2.
131
DRIVEABILITY - DIESEL

TEST ACTION APPLICABILITY
1NOTE: If the ECM detects and stores a DTC, the ECM also stores the
engine/vehicle operating conditions under which the DTC was set. Some of
these conditions are displayed on the DRB at the same time the DTC is
displayed.
NOTE: Before erasing stored DTCs, record these conditions. Attempting to
duplicate these conditions may assist when checking for an active DTC.
Turn the ignition on.
With the DRB, erase ECM DTCs.
Turn the ignition off for 10 seconds.
Test drive the vehicle.
Monitor the DRB for ECM DTCs.
Did this DTC set again?All
Ye s!Go To 2
No!Go To 9
2 Turn the ignition off.
Using the Service Information wiring diagrams, inspect the wiring and connectors
between the ECM and the O2 sensor for damage, corrosion, poor terminal contact or
other problems.
Were any problems found?All
Ye s!Clean, repair or replace as necessary.
Perform ROAD TEST VERIFICATION - VER-2.
No!Go To 3
3 Turn the ignition off.
Disconnect the O2 Sensor harness connector.
Turn the ignition on.
Using a 12-volt test light connected to ground, check the Power Supply circuit at the
O2 harness connector cavity 4.
Does the test light illuminate brightly?All
Ye s!Go To 4
No!Repair the Power Supply circuit for an open or short to ground.
Perform ROAD TEST VERIFICATION - VER-2.
4 Turn the ignition off.
Disconnect the O2 Sensor harness connector.
Disconnect the ECM harness connectors.
Perform the following resistance measurements from the O2 harness connector to the
ECM harness connector.
O2 Sensor Cavity 1 to ECM Cavity C1-15.
O2 Sensor Cavity 2 to ECM Cavity C1-40.
O2 Sensor Cavity 3 to ECM Cavity C1-72.
O2 Sensor Cavity 5 to ECM Cavity C1-62.
O2 Sensor Cavity 6 to ECM Cavity C1-39.
Is the resistance below 10.0 ohms for each measurement?All
Ye s!Go To 5
No!Repair the circuit(s) that measured above 10.0 ohms for an open.
Perform ROAD TEST VERIFICATION - VER-2.
135
DRIVEABILITY - DIESEL
P2026-O2 SENSOR CIRCUIT FAULT ÐContinued