Page 705 of 5267
P0541-LOW VOLTAGE ON THE #1 INTAKE AIR HEATER RELAY
For a complete wiring diagramRefer to Section 8W.
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)
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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 708 of 5267
P0542-HIGH VOLTAGE ON THE #1 INTAKE AIR HEATER RELAY
For a complete wiring diagramRefer to Section 8W.
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)
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4.SIGNAL CIRCUIT SHORTED TO BATTERY NEGATIVE
Disconnect the ECM harness connector(s).
NOTE: Check connectors - Clean/repair as necessary.
Measure the resistance between the signal circuit of the intake air heaterrelay and battery negative.
Is the resistance greater than 100 K ohms?
Ye s>>
Go To 5
No>>
Repair 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)
5.SIGNAL CIRCUIT SHORTED TO OTHER CIRCUITS
Measure the resistance between the signal circuit of the intake air heaterrelay and all other circuits in the ECM
harness connector.
Is the resistance greater than 100 K ohms?
Ye s>>
Go To 6
No>>
Repair signal circuit shorted to other circuits.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 8 - ELECTRICAL/ELEC-
TRONIC CONTROL MODULES/ENGINE CONTROL MODULE - DIAGNOSIS AND TESTING)
6.ECM
Reconnect the ECM harness connectors.
Turn the ignition on.
Disconnect the intake air heater relay signal wire.
Did DTC P0542 or 2608 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 711 of 5267
P0562-BATTERY VOLTAGE LOW
For a complete wiring diagramRefer to Section 8W.
Page 712 of 5267

When Monitored:
With the key on or the engine running.
Set Condition:
The battery voltage detected by the ECM is less than a calibrated value.
Possible Causes
P0622 PRESENT
P2502 PRESENT
P2503 PRESENT
BATTERY TERMINAL CONNECTIONS
ACCESSORY WIRING
BATTERY
HIGH RESISTANCE IN WIRE HARNESS
ECM
INTERMITTENT CONDITION
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE -
DIAGNOSIS AND TESTING)
Diagnostic Test
1.P0622 PRESENT
With the scan tool, read DTCs.
Is P0622 set?
Ye s>>
Repair P0622 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.P2502 PRESENT
With the scan tool, read DTCs.
Is P2502 set?
Ye s>>
Repair P2502 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 3
3.P2503 PRESENT
With the scan tool, read DTCs.
Is P2503 set?
Ye s>>
Repair P2503 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 4