
Symptom:
P2306-SENSOR SUPPLY 2 VOLTAGE IS TOO LOW
POSSIBLE CAUSES
BOOST PRESSURE SENSOR
FUEL PRESSURE SENSOR
VISUAL WIRING AND CONNECTOR INSPECTION
INTERMITTENT CONDITION
SENSOR SUPPLY VOLTAGE 2 SHORTED TO GROUND
BOOST PRESSURE SENSOR SIGNAL CIRCUIT SHORTED TO SENSOR GROUND CIRCUIT
ENGINE CONTROL MODULE
FUEL PRESSURE SENSOR SIGNAL CIRCUIT SHORTED TO SENSOR GROUND CIRCUIT
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.
Turn the ignition on.
Monitor the DRB for ECM DTCs.
Did this DTC set again?All
Ye s!Go To 2
No!Go To 8
2 Turn the ignition off.
Visually inspect the wiring and connectors associated with the Boost Pressure Sensor
and Fuel Pressure Sensor for problems that may result in a short circuit.
Were any problems found?All
Ye s!Repair or replace wiring/connectors as necessary.
Perform ROAD TEST VERIFICATION - VER-2.
No!Go To 3
3 Turn the ignition off.
Disconnect the Boost Pressure Sensor and Fuel Pressure Sensor harness connectors.
Disconnect the ECM harness connectors.
Measure the resistance between ground and all of the Fuel Pressure Sensor and
Boost Pressure Sensor harness connector cavities.
Is the voltage below 1000 ohms for any of the measurements?All
Ye s!Repair the circuit(s) that measured below 1000 ohms for a short to
ground.
Perform ROAD TEST VERIFICATION - VER-2.
No!Go To 4
200
DRIVEABILITY - DIESEL

Symptom:
P2332-SENSOR SUPPLY 3 VOLTAGE IS TOO LOW
POSSIBLE CAUSES
ENGINE OIL SENSOR
INTAKE AIR PRESSURE SENSOR
VISUAL WIRING AND CONNECTOR INSPECTION
INTERMITTENT CONDITION
SENSOR SUPPLY VOLTAGE 3 SHORTED TO GROUND
ENGINE CONTROL MODULE
ENGINE OIL SENSOR SIGNAL CIRCUIT SHORTED TO SENSOR GROUND CIRCUIT
INTAKE AIR PRESSURE SENSOR SIGNAL CIRCUIT SHORTED TO SENSOR GROUND CIRCUIT
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.
Turn the ignition on.
Monitor the DRB for ECM DTCs.
Did this DTC set again?All
Ye s!Go To 2
No!Go To 8
2 Turn the ignition off.
Visually inspect the wiring and connectors associated with the Intake Air Pressure
Sensor and Engine Oil Sensors for problems that may result in a short circuit.
Were any problems found?All
Ye s!Repair or replace wiring/connectors as necessary.
Perform ROAD TEST VERIFICATION - VER-2.
No!Go To 3
3 Turn the ignition off.
Disconnect the Intake Air Pressure Sensor and Engine Oil Sensor harness connec-
tors.
Disconnect the ECM harness connectors.
Measure the resistance between ground and all of the EOS and Intake Air Pressure
Sensor harness connector cavities.
Is the voltage below 1000 ohms for any of the measurements?All
Ye s!Repair the circuit(s) that measured below 1000 ohms for a short to
ground.
Perform ROAD TEST VERIFICATION - VER-2.
No!Go To 4
203
DRIVEABILITY - DIESEL

Symptom:
P2332-SENSOR SUPPLY 3 VOLTAGE IS TOO HIGH
POSSIBLE CAUSES
EO SENSOR
INTAKE AIR PRESSURE SENSOR
VISUAL WIRING AND CONNECTOR INSPECTION
INTERMITTENT CONDITION
SENSOR SUPPLY VOLTAGE 3 SHORTED TO VOLTAGE
ENGINE CONTROL MODULE
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.
Start the engine.
Monitor the DRB for ECM DTCs.
Did this DTC set again?All
Ye s!Go To 2
No!Go To 6
2 Turn the ignition off.
Visually inspect the wiring and connectors associated with the Intake Air Pressure
Sensor and Engine Oil Sensors for problems that may result in a short circuit.
Were any problems found?All
Ye s!Repair or replace wiring/connectors as necessary.
Perform ROAD TEST VERIFICATION - VER-2.
No!Go To 3
206
DRIVEABILITY - DIESEL

Symptom List:
P2333-S/C VEHICLE SPEED PLAUSIBILITY
P2338-S/C EXCESSIVE ACCELERATION
P2338-S/C EXCESSIVE DECELERATION
Test Note: All symptoms listed above are diagnosed using the same tests.
The title for the tests will be P2333-S/C VEHICLE SPEED
PLAUSIBILITY.
POSSIBLE CAUSES
BRAKE SWITCH VERIFICATION
CAB DTCS
OPEN CAN BUS CIRCUITS
VERIFY CAB COMMUNICATION
WHEEL SPEED VERIFICATION
INTERMITTENT CONDITION
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.
With the DRBIIIt, erase ECM DTCs.
Test drive the vehicle and attempt to duplicate the problem.
With the DRB, read ECM DTC's.
Did this DTC set again?All
Ye s!Go To 2
No!Go To 7
2 Turn the ignition on.
With the DRBIIItattempt to communicate with the CAB.
NOTE: If there are other DTCs set with this DTC, refer to the Symptom List
and repair other stored ECM DTCs before diagnosing this DTC.
Is the CAB communicating with the DRB?All
Ye s!Go To 3
No!Refer to the appropriate symptom in the Body Diagnostic Infor-
mation.
Perform ROAD TEST VERIFICATION - VER-2.
209
DRIVEABILITY - DIESEL

TEST ACTION APPLICABILITY
3 Turn the ignition on.
With the DRBIIIt, read the CAB DTCs.
Are there any CAB DTCs?All
Ye s!Refer to symptom list for problems related to CAB.
Perform ROAD TEST VERIFICATION - VER-2.
No!Go To 4
4 Turn the ignition off.
Disconnect the CAB Module harness connector.
Disconnect the ECM harness connectors.
Measure the resistance of each CAN Bus circuit between the ECM harness connector
and the CAB harness connector.
Is the resistance below 10.0 ohms for each measurement?All
Ye s!Go To 5
No!Repair the open CAN Bus circuit(s) between the ECM and the
SKREEM.
Perform ROAD TEST VERIFICATION - VER-2.
5 With the DRBIIIt, perform the Wheel Speed Test of the ABS system.
Were any problems found?All
Ye s!Repair wheel speed signal problem as necessary.
Perform ROAD TEST VERIFICATION - VER-2.
No!Go To 6
6 Check the Brake Switch for proper operation and adjustment.
Were any problems found?All
Ye s!Adjust or replace the Brake Switch as necessary.
Perform ROAD TEST VERIFICATION - VER-2.
No!Test Complete.
7WARNING: WHEN THE ENGINE IS OPERATING, DO NOT STAND IN A
DIRECT LINE WITH THE FAN. DO NOT PUT YOUR HANDS NEAR THE
PULLEYS, BELTS OR FAN. DO NOT WEAR LOOSE CLOTHING.
NOTE: The conditions that set the DTC are not present at this time. The
following list may help in identifying the intermittent condition.
With the engine running at normal operating temperature, monitor the DRB
parameters related to the DTC while wiggling the wiring harness. Look for param-
eter values to change and/or a DTC to set.
Review the DTC When Monitored and Set Conditions. If possible, try to duplicate the
conditions under which the DTC was set.
Refer to any Technical Service Bulletins (TSB) that may apply.
Visually inspect the related wiring harness. Look for any chafed, pierced, pinched, or
partially broken wires.
Visually inspect the related wiring harness connectors. Look for broken, bent, pushed
out, or corroded terminals.
Were any of the above conditions present?All
Ye s!Repair as necessary.
Perform ROAD TEST VERIFICATION - VER-2.
No!Test Complete.
210
DRIVEABILITY - DIESEL
P2333-S/C VEHICLE SPEED PLAUSIBILITY ÐContinued

Symptom List:
P2339-ECM CHECKSUM ERROR #1
P2339-ECM CHECKSUM ERROR #2
P2339-ECM INVALID CODING
P2339-ECM INVALID DATA
Test Note: All symptoms listed above are diagnosed using the same tests.
The title for the tests will be P2339-ECM CHECKSUM ERROR
#1.
POSSIBLE CAUSES
ENGINE CONTROL MODULE
TEST ACTION APPLICABILITY
1NOTE: This DTC indicates that an error occurred during ECM program-
ming.
Turn the ignition on.
With the DRBIIIt, erase ECM DTCs.
Refer to the Service Information and attempt to reprogram the ECM.
Perform several engine run cycles, turning the ignition off for at least 20 seconds
between each engine run cycle.
With the DRBIIIt, read the ECM DTCs.
Did this DTC set again?All
Ye s!Replace and program the Engine Control Module in accordance
with the Service Information.
Perform ROAD TEST VERIFICATION - VER-2.
No!Test Complete.
211
DRIVEABILITY - DIESEL

Symptom:
P2344-KICKDOWN SWITCH PLAUSIBILITY
POSSIBLE CAUSES
INTERMITTENT CONDITION
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: If there are any Accelerator Pedal Position Sensor DTC's present,
repair the APP Sensor DTC's before continuing.
Turn the ignition on.
With the DRB, erase ECM DTCs.
Turn the ignition off for 10 seconds.
Test drive the vehicle. Be sure to completely depress the accelerator pedal several
times to activate the Kickdown Switch.
Monitor the DRB for ECM DTCs.
Did this DTC set again?All
Ye s!Test Complete.
No!Go To 2
2WARNING: WHEN THE ENGINE IS OPERATING, DO NOT STAND IN A
DIRECT LINE WITH THE FAN. DO NOT PUT YOUR HANDS NEAR THE
PULLEYS, BELTS OR FAN. DO NOT WEAR LOOSE CLOTHING.
NOTE: The conditions that set the DTC are not present at this time. The
following list may help in identifying the intermittent condition.
With the engine running at normal operating temperature, monitor the DRB
parameters related to the DTC while wiggling the wiring harness. Look for param-
eter values to change and/or a DTC to set.
Review the DTC When Monitored and Set Conditions. If possible, try to duplicate the
conditions under which the DTC was set.
Refer to any Technical Service Bulletins (TSB) that may apply.
Visually inspect the related wiring harness. Look for any chafed, pierced, pinched, or
partially broken wires.
Visually inspect the related wiring harness connectors. Look for broken, bent, pushed
out, or corroded terminals.
Were any of the above conditions present?All
Ye s!Repair as necessary.
Perform ROAD TEST VERIFICATION - VER-2.
No!Test Complete.
212
DRIVEABILITY - DIESEL

Symptom:
P2351-ECM SUPPLY VOLTAGE TOO LOW
POSSIBLE CAUSES
ECM
ECM IGNITION CIRCUIT OPEN
STARTER OR LIFT PUMP RELAY CIRCUIT(S) SHORTED TO GROUND
INTERMITTENT CONDITION
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 4
2 Turn the ignition off.
Disconnect the ECM harness connectors.
Remove the Starter Relay and disconnect the Fuel Lift Pump harness connector
Measure the resistance between ground and the Starter Relay control circuit.
Measure the resistance between ground and the Fuel Lift Pump Relay control circuit.
Did both circuits measure above 1000 ohms?All
Ye s!Go To 3
No!Repair the relay control circuit(s) that did not measure above
1000 ohms for a short to ground.
Perform ROAD TEST VERIFICATION - VER-2.
3 Turn the ignition off.
Disconnect the ECM harness connectors.
Using the Service Wiring Information determine which circuits in the ECM harness
connector provide Ignition Switch power to the ECM.
Turn the ignition on.
Using a 12-volt test light connected to ground, check each Ignition Switch Output
circuits in the ECM harness connectors.
Does the test light illuminate brightly for each circuit?All
Ye s!Replace the ECM in accordance with the Service Information.
Perform ROAD TEST VERIFICATION - VER-2.
No!Repair the Ignition Supply circuit as necessary.
Perform ROAD TEST VERIFICATION - VER-2.
214
DRIVEABILITY - DIESEL