P0541

P0541-INTAKE AIR HEATER CONTROL CIRCUIT 1 LOW





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 and the Intake Air Heater Relay is commanded OFF.

- Set Condition:
The Powertrain Control Module (PCM) is reading low voltage on the Intake Air Heater Relay Control circuit when performing a diagnostic check of the circuit.





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, read DTCs.

Is the DTC active?

Yes

- Go To 2

No

- Perform the INTERMITTENT CONDITION - 6.7L diagnostic procedure. Intermittent Condition Test

2. CHECK THE (K174) INTAKE AIR HEATER RELAY CONTROL CIRCUIT FOR A SHORT TO GROUND
1. Turn ignition off.
2. Disconnect the (K174) Intake Air Heater Relay Control circuit connector at the Intake Air Heater Relay.
3. Disconnect the (K974) Intake Air Heater Relay Control Return circuit connector at the Intake Air Heater Relay.
4. Disconnect the PCM C2 harness connector.
5. Measure resistance between ground and the (K174) Intake Air Heater Relay Control circuit at the Intake Air Heater Relay Control circuit connector at the Intake Air Heater Relay.

Is the resistance above 10k Ohms?

Yes

- Go To 3

No

- Repair the (K174) Intake Air Heater Relay Control circuit for a short to ground.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

3. CHECK FOR THE (K174) INTAKE AIR HEATER RELAY CONTROL CIRCUIT SHORTED TO THE (K974) INTAKE AIR HEATER RELAY CONTROL RETURN CIRCUIT
1. Measure the resistance between the (K174) Intake Air Heater Relay Control circuit and the (K974) Intake Air Heater Relay Control Return circuit at the terminals for the Intake Air Heater Relay.

Is the resistance above 10k Ohms?

Yes

- Go To 4

No

- Repair the short between the (K174) Intake Air Heater Relay Control circuit and the (K974) Intake Air Heater Relay Control circuit.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

4. INTAKE AIR HEATER RELAY CONTROL

CAUTION: Excessive actuation to the Intake Air Heater may overheat and damage the heater assembly. Allow the Intake Air heater to cool for five minutes between each actuation procedure to prevent any possible damage from overheating to occur to the Intake Air Heater.

1. Turn ignition off.
2. Replace the Intake Air Heater Relay.
3. Reconnect all previously disconnected connectors.
4. Turn ignition on.
5. With the scan tool, erase DTCs.
6. Using a scan tool, actuate the Cold Start Aid Driver 1 Output circuit.

NOTE: Set the actuation to toggle.

7. With the scan tool, read DTCs.

Did the DTC return?

Yes

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

No

- Repair complete.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.