Page 698 of 5267
7.(F855) 5-VOLT SUPPLY CIRCUIT OPEN FROM ECM HARNESS CONNECTOR TO A/C HARNESSCONN
Measure the resistance of the (F855) 5-volt supply circuit between the
sensor harness connector and the ECM harness connector.
Is the resistance less than 10 Ohms?
Ye s>>
Go To 8
No>>
Repair the open (F855) 5-volt supply circuit.
Perform POWERTRAIN VERIFICATION TEST VER - 1
(DIESEL). (Refer to 8 - ELECTRICAL/ELECTRONIC CON-
TROL MODULES/ENGINE CONTROL MODULE - DIAG-
NOSIS AND TESTING)
8.(C918) SIGNAL CIRCUIT SHORTED TO GROUND
Measure the resistance between the (C918) signal circuit in the sensor
harness connector and battery negative.
Is the resistance greater than 100k Ohms?
Ye s>>
Go To 9
No>>
Repair the (C918) signal circuit shorted to ground.
Perform POWERTRAIN VERIFICATION TEST VER - 1
(DIESEL). (Refer to 8 - ELECTRICAL/ELECTRONIC CON-
TROL MODULES/ENGINE CONTROL MODULE - DIAG-
NOSIS AND TESTING)
Page 699 of 5267
9.(F855) 5-VOLT SUPPLY CIRCUIT SHORTED TO GROUND
Measure the resistance between the (F855) 5-volt supply circuit in the
sensor harness connector and battery negative.
Is the resistance greater than 100k Ohms?
Ye s>>
Go To 10
No>>
Repair the (F855) 5-volt supply circuit shorted to ground.
Perform POWERTRAIN VERIFICATION TEST VER - 1
(DIESEL). (Refer to 8 - ELECTRICAL/ELECTRONIC CON-
TROL MODULES/ENGINE CONTROL MODULE - DIAG-
NOSIS AND TESTING)
10.ECM
Reconnect the ECM harness connectors.
Turn the ignition on.
While monitoring scan tool, use a jumper wire to connect the (F855)
5-volt supply circuit with the (C918) signal circuit at the sensor harness
connector.
Did DTC P0533 set?
Ye s>>
Te s t C o m p l e t e .
No>>
Replace the ECM.
Perform POWERTRAIN VERIFICATION TEST VER - 1
(DIESEL). (Refer to 8 - ELECTRICAL/ELECTRONIC CON-
TROL MODULES/ENGINE CONTROL MODULE - DIAG-
NOSIS AND TESTING)
Page 701 of 5267

When Monitored:
With the ignition on and battery voltage greater than 10.4 volts.
Set Condition:
The circuit voltage to the ECM is above a calibrated threshold for a certainperiod of time.
Possible Causes
OTHER DTC’S
A/C PRESSURE SENSOR
(C918) SIGNAL CIRCUIT SHORTED TO BATTERY POSITIVE
(F855) 5-VOLT SUPPLY CIRCUIT SHORTED TO BATTERY POSITIVE
(K916) RETURN CIRCUIT OPEN FROM ECM HARNESS CONNECTOR TO A/C HARNESS CONNECTOR
ECM
INTERMITTENT CONDITION
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE -
DIAGNOSIS AND TESTING)
Diagnostic Test
1.OTHER DTC’S
Turn the ignition on.
With the scan tool, read DTCs.
Are other DTC’s present?
Ye s>>
Repair other DTC’s first.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 8 - ELECTRICAL/ELEC-
TRONIC CONTROL MODULES/ENGINE CONTROL MODULE - DIAGNOSIS AND TESTING)
No>>
Go To 2
2.HARNESS OPEN
Turn the ignition off.
Disconnect the A/C pressure sending unit harness connector.
Check connectors - Clean/repair as necessary.
Turn the ignition on.
Measure the voltage between the (F855) 5-volt supply circuit and
(K916) return circuit of the sensor harness connector.
Is the voltage between 4.5 and 5.5 volts?
Ye s>>
Go To 3
No>>
Go To 4
Page 702 of 5267
3.A/C PRESSURE SENSOR
While monitoring scan tool, use a jumper wire to connect the (K916)
return circuit to the (C918) signal circuit at the sensor harness connec-
tor.
Did P0532 set?
Ye s>>
Replace the A/C pressure sensor.
Perform POWERTRAIN VERIFICATION TEST VER - 1
(DIESEL). (Refer to 8 - ELECTRICAL/ELECTRONIC CON-
TROL MODULES/ENGINE CONTROL MODULE - DIAG-
NOSIS AND TESTING)
No>>
Go To 4
4.(F855) 5-VOLT SUPPLY CIRCUIT SHORTED TO BATTERY NEGATIVE
Turn the ignition off.
Disconnect the ECM harness connectors.
Check connectors - Clean/repair as necessary.
Measure the voltage between the (F855) 5-volt supply circuit at the har-
ness connector and battery negative.
Is the voltage less than 1 volt?
Ye s>>
Go To 5
No>>
Repair the (F855) 5-volt supply circuit shorted to the battery
negative.
Perform POWERTRAIN VERIFICATION TEST VER - 1
(DIESEL). (Refer to 8 - ELECTRICAL/ELECTRONIC CON-
TROL MODULES/ENGINE CONTROL MODULE - DIAG-
NOSIS AND TESTING)
Page 703 of 5267
5.(C918) SIGNAL CIRCUIT SHORTED TO BATTERY NEGATIVE
Measure the voltage between the (C918) signal circuit at the harness
connector and battery negative.
Is the voltage less than 1 volt?
Ye s>>
Go To 6
No>>
Repair the (C918) signal circuit shorted to the battery neg-
ative.
Perform POWERTRAIN VERIFICATION TEST VER - 1
(DIESEL). (Refer to 8 - ELECTRICAL/ELECTRONIC CON-
TROL MODULES/ENGINE CONTROL MODULE - DIAG-
NOSIS AND TESTING)
6.(K916) RETURN CIRCUIT OPEN FROM ECM HARNESS CONNECTOR TO A/C HARNESS CONNECTOR
Measure the resistance of the (K916) return circuit between the sensor
harness connector and the ECM harness connector.
Is the resistance less than 10 Ohms?
Ye s>>
Go To 7
No>>
Repair the open (K916) return circuit.
Perform POWERTRAIN VERIFICATION TEST VER - 1
(DIESEL). (Refer to 8 - ELECTRICAL/ELECTRONIC CON-
TROL MODULES/ENGINE CONTROL MODULE - DIAG-
NOSIS AND TESTING)
Page 706 of 5267

When Monitored:
When the ignition is on.
Set Condition:
When the signal from the #1 intake air heater output does not match the signal from the #1 intake air heater
feedback.
Possible Causes
LOOSE CONNECTION
INTAKEAIRHEATERRELAY
SIGNAL CIRCUIT OPEN FROM RELAY TO ECM
SIGNAL CIRCUIT SHORTED TO BATTERY NEGATIVE
ECM
INTERMITTENT CONDITION
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE -
DIAGNOSIS AND TESTING)
Diagnostic Test
1.RELAY CLICKING
Ignition on, engine not running.
With the scan tool, actuate the #1 Intake Air Heater.
Can you hear the Relay clicking?
Ye s>>
Go To 2
No>>
Go To 3
2.LOOSE CONNECTION
While the relay is clicking , wiggle the wiring harness and connectors.
Does this interrupt the clicking?
Ye s>>
Repair the poor connection.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 8 - ELECTRICAL/ELEC-
TRONIC CONTROL MODULES/ENGINE CONTROL MODULE - DIAGNOSIS AND TESTING)
No>>
Go To 3
3.INTAKE AIR HEATER RELAY
Turn the ignition off.
Remove the Intake Air Heater #1 Relay.
Check connectors - Clean/repair as necessary.
Measure the resistance between the signal and return posts of the intake air heater relay.
Is the resistance between 15 and 25 Ohms?
Ye s>>
Go To 4
No>>
Replace the Intake Air Heater #1 relay.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 8 - ELECTRICAL/ELEC-
TRONIC CONTROL MODULES/ENGINE CONTROL MODULE - DIAGNOSIS AND TESTING)
Page 707 of 5267

4.SIGNAL CIRCUIT OPEN FROM RELAY TO ECM
Disconnect the ECM harness connectors.
Check connectors - Clean/repair as necessary.
Measure the resistance of the intake air heater relay signal circuit between the ECM connector and the intake air
heater relay connector.
Is the resistance less than 10 Ohms?
Ye s>>
Go To 5
No>>
Repair the open signal circuit from PDC to ECM harness connector.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 8 - ELECTRICAL/ELEC-
TRONIC CONTROL MODULES/ENGINE CONTROL MODULE - DIAGNOSIS AND TESTING)
5.SIGNAL CIRCUIT SHORTED TO BATTERY NEGATIVE
Measure the voltage between the signal circuit of the intake air heater relay and battery negative.
Is the voltage greater than 1 volts?
Ye s>>
Repair the signal circuit shorted to Battery negative.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 8 - ELECTRICAL/ELEC-
TRONIC CONTROL MODULES/ENGINE CONTROL MODULE - DIAGNOSIS AND TESTING)
No>>
Go To 6
6.ECM
Reconnect the ECM harness connectors.
Disconnect the intake air heater relay signal wire and use a jumper to connect it to battery negative.
Turn the ignition on.
With the scan tool, read DTCs.
Did DTC P0542 set?
Ye s>>
Refer to the INTERMITTENT CONDITION Symptom (Diagnostic Procedure). (Refer to 9 - ENGINE -
DIAGNOSIS AND TESTING)
No>>
Replace the ECM.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 8 - ELECTRICAL/ELEC-
TRONIC CONTROL MODULES/ENGINE CONTROL MODULE - DIAGNOSIS AND TESTING)
Page 709 of 5267

When Monitored:
When the ignition is on.
Set Condition:
When the signal from the #1 Intake Air Heater output does not match the signal from the #1 Intake Air Heater
feedback.
Possible Causes
LOOSE CONNECTION
INTAKEAIRHEATERRELAY
SIGNAL CIRCUIT SHORTED TO BATTERY NEGATIVE
ECM
INTERMITTENT CONDITION
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE -
DIAGNOSIS AND TESTING)
Diagnostic Test
1.RELAY CLICKING
Ignition on, engine not running.
With the scan tool, actuate the Intake Air Heater relay.
Can you hear the Relay clicking?
Ye s>>
Go To 2
No>>
Go To 3
2.LOOSE CONNECTION
While the relay is clicking , wiggle the wiring harness and connectors.
Does this interrupt the clicking?
Ye s>>
Repair the poor connection.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 8 - ELECTRICAL/ELEC-
TRONIC CONTROL MODULES/ENGINE CONTROL MODULE - DIAGNOSIS AND TESTING)
No>>
Go To 3
3.INTAKE AIR HEATER RELAY
Turn the ignition off.
Remove the Intake Air Heater Relay.
NOTE: Check connectors - Clean/repair as necessary.
Measure the resistance between the signal and return posts of the intake air heater relay.
Is the resistance between 15 and 25 Ohms?
Ye s>>
Go To 4
No>>
Replace the Intake Air Heater relay.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 8 - ELECTRICAL/ELEC-
TRONIC CONTROL MODULES/ENGINE CONTROL MODULE - DIAGNOSIS AND TESTING)