P0542

P0542-INTAKE AIR HEATER CONTROL CIRCUIT 1 HIGH





For a complete wiring diagram, refer to the Wiring Information.

Theory of Operation

The Intake Air Heater is integrated into the intake manifold cover. The Intake Air Heater element is used to heat the air coming into the Intake Manifold. This is done to help engine starting and improve driveability with cool or cold outside temperatures. Electrical supply for the air heater element is controlled by the Powertrain Control Module (PCM) through the Intake Air Heater Relay. One heavy duty cable connects the air heater element to the Intake Air Heater Relay. This cable will supply 12 Volts to the air heater elements. The PCM will light the MIL lamp as soon as this diagnostic runs and fails. The PCM will turn off the MIL lamp when the diagnostic runs and passes in four consecutive drive cycles.

- When Monitored:
When the ignition is on.

- Set Condition:
When the signal from the Intake Air Heater output does not match the signal from the Intake Air Heater feedback.





Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Pre-Diagnostic Troubleshooting Procedure.

1. ACTIVE DTC
1. Turn the ignition on.
2. With the scan tool, record all Freeze frame data.
3. With the scan tool, erase DTCs.
4. Turn the ignition off for 75 seconds.
5. Turn the ignition on.
6. With the scan tool, read DTCs.

Did the DTC return?

Yes

- Go To 2

No

- Perform the INTERMITTENT CONDITION diagnostic procedure. . Intermittent Condition Test

2. CHECK THE INTAKE AIR HEATER RELAY
1. Turn the ignition off.
2. Remove the Intake Air Heater Relay.

NOTE: Check connectors - Clean/repair as necessary.

3. Measure the resistance between the signal and return posts of the Intake Air Heater Relay.

Is the resistance between 15.0 and 25.0 Ohms?

Yes

- Go To 3

No

- Replace the Intake Air Heater Relay.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

3. CHECK THE (K974) INTAKE AIR HEATER RELAY CONTROL RETURN FOR A SHORT TO VOLTAGE
1. Remove the Intake Air Heater Relay.
2. Measure the voltage of the (K974) Intake Air Heater Relay Control Return circuit at the Intake Air Heater Relay connector.

Is there any voltage present?

Yes

- Repair the (K974) Intake Air Heater Relay Control Return circuit for a short to voltage.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

No

- Go To 4

4. CHECK THE (K974) INTAKE AIR HEATER RELAY CONTROL RETURN FOR AN OPEN/HIGH RESISTANCE
1. Measure the resistance of the (K974) Intake Air Heater Relay Control Return circuit between the Intake Air Heater Relay connector and the PCM C2 harness connector.
2. Disconnect the PCM C2 harness connector.

Is the resistance below 5.0 Ohms?

Yes

- Repair the (K974) Intake Air Heater Relay Control Return circuit for an open or high resistance.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

No

- Replace the Powertrain Control Module.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.