P0542 HIGH VOLTAGE ON THE #1 INTAKE AIR HEATER RELAY

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
• INTAKE AIR HEATER RELAY
• SIGNAL CIRCUIT SHORTED TO BATTERY NEGATIVE
• ECM
• INTERMITTENT CONDITION

DIAGNOSTIC PROCEDURE

1. Ignition on, engine not running.

With the DRBIII®, actuate the Intake Air Heater relay.
Can you hear the Relay clicking?
Yes --> Go To 2
No --> Go To 3
2. While the relay is clicking, wiggle the wiring harness and connectors.
Does this interrupt the clicking?
Yes --> Repair the poor connection.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL).
No --> Go To 3
3. Turn the ignition off.
Remove the Intake Air Heater 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?
Yes --> Go To 4
No --> Replace the Intake Air Heater relay.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL).
4. Disconnect the ECM harness connector(s).
Check connectors - Clean/repair as necessary.
Measure the resistance between the signal circuit of the intake air heater relay and battery negative.
Is the resistance greater than 100 K ohms?
Yes --> Go To 5
No --> Repair signal circuit shorted to battery negative.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL).

5. Reconnect the ECM harness connectors.
Turn the ignition on.
Disconnect the intake air heater relay signal wire.
Did DTC P0542 or 2608 set?
Yes --> Refer to the SYMPTOM: INTERMITTENT CONDITION Symptom (Diagnostic
Procedure).
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL).
No --> Replace the ECM.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL).