P0541

P0541-INTAKE AIR HEATER CONTROL CIRCUIT 1 LOW





For a complete wiring diagram refer to the Wiring Information Electrical Diagrams.

Theory of Operation

The intake air heater is integrated into the intake manifold cover. The air heater element is used to heat incoming air 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 ECM through the air heater relay. One heavy duty cable connects the air heater element to the air heater relay. This cable will supply 12 volts to air heater elements. The ECM will light the MIL lamp as soon as this diagnostic runs and fails. The ECM will turn off the MIL lamp when the diagnostic runs and passes in 4 consecutive drive cycles.

- When Monitored:
When the ignition is on.

- Set Condition:
Intake Air Heater Relay is commanded off, but the ECM is still reading voltage on the Intake Air Heater Relay Control Return 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, erase DTCs.
4. Turn the ignition off for 30 seconds.
5. Turn the ignition on.
6. With the scan tool, read DTCs.

Did the DTC reset?

Yes

- Go To 2

No

- Refer to the INTERMITTENT CONDITION - DIESEL (Diagnostic Procedure). Intermittent Condition Test

2. (K974) INTAKE AIR HEATER RELAY CONTROL RETURN SHORTED 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 short to voltage on the (K974) Intake Air Heater Relay Control Return circuit (terminal 86).
- Perform POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test

No

- Replace the Intake Air Heater Relay.
- Go To 3

3. ECM
1. With the scan tool, erase DTCs.
2. Turn the ignition off for 30 seconds.
3. Turn the ignition on.
4. With the scan tool, read DTCs.

Did the DTC reset?

Yes

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

No

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