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.

- Set Condition:
Intake Air Heater Relay is commanded off, but the Powertrain Control Module (PCM) 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 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 (K974) INTAKE AIR HEATER RELAY CONTROL RETURN FOR A SHORT TO GROUND




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 PCM C2 harness connector.

NOTE: Check connectors - Clean/repair as necessary.

4. Measure the resistance between ground and the (K974) Intake Air Heater Relay Control Return circuit at the PCM C2 harness connector.

Is the resistance below 10K Ohms?

Yes

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

No

- Go To 3

3. CHECK THE INTAKE AIR HEATER RELAY
1. Reconnect the PCM C2 harness connector.
2. Replace the Intake Air Heater Relay with a known good relay.
3. Turn the ignition on.
4. With the scan tool, erase DTCs.
5. Turn the ignition off for 75 seconds.
6. Turn the ignition on.
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.