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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 - 6.7L diagnostic procedure. . Intermittent Condition Test

2. CHECK THE INTAKE AIR HEATER RELAY




1. Turn the ignition off.
2. Disconnect the (K974) Intake Air Heater Relay Control Return circuit connector at the Intake Air Heater Relay.
3. Disconnect the (K174) Intake Air Heater Relay Control circuit connector at the Intake Air Heater Relay.
4. 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 2

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 CIRCUIT FOR AN OPEN/HIGH RESISTANCE
1. Turn ignition off.
2. Disconnect the PCM C2 harness connector.
3. Measure the resistance of the (K974) Intake Air Heater Relay Control Return circuit between the (K974) Intake Air Heater Relay Control Return circuit connector and the PCM C2 harness connector.

Is the resistance below 5.0 Ohms?

Yes

- Go To 4

No

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

4. CHECK THE (K974) INTAKE AIR HEATER RELAY CONTROL RETURN FOR A SHORT TO VOLTAGE
1. Measure the between the (K974) Intake Air Heater Relay Control Return circuit and all other circuits at the PCM C2 harness connector.

Is the resistance above 10k Ohms between the (K974) Intake Air Heater Relay Control Return circuit and all other circuits?

Yes

- Repair the (K974) Intake Air Heater Relay Control Return circuit for a short to the circuit that measured below 10k Ohms.
- 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.