
TEST ACTION APPLICABILITY
3 Turn the ignition off.
Install a substitute relay in place of the Engine Control Relay.
Turn the ignition on.
With the DRBIIIt, erase DTCs.
Perform several ignition key cycles, pausing for at least 10 seconds between each
cycle.
Turn the ignition on.
With the DRB, read ECM DTCs.
Did this DTC set again?All
Ye s!Go To 4
No!Replace the Engine Control Relay.
Perform ROAD TEST VERIFICATION - VER-2.
4 Refer to symptom Checking the ECM Power and Grounds.
Are the ECM Power and Ground circuits o.k.?All
Ye s!Replace the ECM in accordance with the Service Information.
Perform ROAD TEST VERIFICATION - VER-2.
No!Repair as necessary.
Perform ROAD TEST VERIFICATION - VER-2.
5WARNING: 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.
88
DRIVEABILITY - DIESEL
P1610-ENGINE CONTROL RELAY PLAUSIBILITY ÐContinued

TEST ACTION APPLICABILITY
3 Turn the ignition on.
With the DRBIIIt, erase ECM DTCs.
Turn the ignition off.
Install a substitute relay in place of the Engine Control Relay.
Perform several ignition key cycles, pausing for at least 10 seconds between each
cycle.
Turn the ignition on.
With the DRB, read ECM DTCs.
Did this DTC set again?All
Ye s!Go To 4
No!Replace the Engine Control Relay.
Perform ROAD TEST VERIFICATION - VER-2.
4 Turn the ignition off.
Remove the Engine Control Relay.
Disconnect the ECM harness connectors.
Measure the resistance of the Engine Control Relay Control circuit while wiggling
the wiring harness and connectors between the ECM and the Fuse Block #1.
Was the resistance above 10.0 ohms at any time while wiggling the wiring harness
and connectors?All
Ye s!Repair the Engine Control Relay Control circuit for an intermit-
tent open.
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.
5WARNING: 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.
90
DRIVEABILITY - DIESEL
P1610-ENGINE CONTROL RELAY SHUTS OFF TOO EARLY ÐContinued

TEST ACTION APPLICABILITY
6WARNING: 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.
93
DRIVEABILITY - DIESEL
P1610-ENGINE CONTROL RELAY SHUTS OFF TOO LATE ÐContinued

TEST ACTION APPLICABILITY
3 Turn the ignition off.
Disconnect the APP and CMP Sensor harness connectors.
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 in Fuse Block No.1.
Turn the ignition on.
Measure the voltage at ECM harness connector cavities C1-38, C1-37, C2-13, C2-24
and C2-25.
Is the voltage above 1.0 volt for any of the measurements?All
Ye s!Repair the circuit(s) that measured above 1.0 volt 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.
4WARNING: 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.
95
DRIVEABILITY - DIESEL
P1611-SENSOR SUPPLY 1 VOLTAGE IS TOO HIGH ÐContinued

TEST ACTION APPLICABILITY
7 Turn the ignition off.
Disconnect the CMP Sensor harness connector.
Turn the ignition on.
With the DRBIIIt, erase ECM DTCs.
Turn the ignition off for 10 seconds. Turn the ignition on.
With the DRBIIIt, read ECM DTCs.
Does the DRB display this DTC?All
Ye s!Replace and program the Engine Control Module in accordance
with the Service Information.
Perform ROAD TEST VERIFICATION - VER-2.
No!Replace the Camshaft Position Sensor.
Perform ROAD TEST VERIFICATION - VER-2.
8WARNING: 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.
98
DRIVEABILITY - DIESEL
P1611-SENSOR SUPPLY 1 VOLTAGE IS TOO LOW ÐContinued

Symptom:
P1612-IGNITION VOLTAGE - VOLTAGE ERROR
POSSIBLE CAUSES
CHECK THE ECM POWER AND GROUNDS
ENGINE CONTROL MODULE
INTERMITTENT CONDITION
TEST ACTION APPLICABILITY
1 Turn the ignition on.
With the DRBIIIt, erase ECM DTCs.
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!Go To 2
No!Go To 3
2 Refer to symptom Checking the ECM Power and Grounds.
Are the ECM Power and Ground circuits o.k.?All
Ye s!Replace the ECM in accordance with the Service Information.
Perform ROAD TEST VERIFICATION - VER-2.
No!Repair as necessary.
Perform ROAD TEST VERIFICATION - VER-2.
3WARNING: 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.
99
DRIVEABILITY - DIESEL

TEST ACTION APPLICABILITY
2 Refer to the symptom list and perform the Checking the ECM Power and Ground
test.
Were any problem found with the ECM powers and grounds?All
Ye s!Repair as necessary.
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.
3WARNING: 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.
101
DRIVEABILITY - DIESEL
P1615-ECM VOLTAGE SUPPLY IS TOO HIGH ÐContinued

TEST ACTION APPLICABILITY
3 Turn the ignition off.
Disconnect the SKREEM Module harness connector.
Disconnect the ECM harness connectors.
Measure the resistance of each CAN Bus circuit between the ECM harness connector
and the SKREEM harness connector.
Is the resistance below 10.0 ohms for each measurement?All
Ye s!Replace and program the SKREEM Module in accordance with
the Service Information.
Perform ROAD TEST VERIFICATION - VER-2.
No!Repair the open CAN Bus circuit(s) between the ECM and the
SKREEM.
Perform ROAD TEST VERIFICATION - VER-2.
4WARNING: 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.
103
DRIVEABILITY - DIESEL
P1630-IMMOBILIZER ÐContinued