P0541

P0541-INTAKE AIR HEATER CONTROL CIRCUIT 1 LOW





For complete wiring diagrams refer to Diagrams/Electrical.


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:

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.

Diagnostic Test


1. RELAY CLICKING

Ignition on, engine not running.

With the scan tool, actuate the Intake Air Heater.

Can you hear the Relay clicking?

Yes

- Go To 2

No

- Go To 3

2. LOOSE CONNECTION

While the relay is clicking, wiggle the wiring harness and connectors.

Does this interrupt the clicking?

Yes

- Repair the poor connection.
- Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test

No

- Go To 3

3. INTAKE AIR HEATER RELAY

Turn the ignition off.

Remove the Intake Air Heater Relay.

Check connectors - Clean/repair as necessary.

Measure the resistance between the signal and return posts of the intake air heater relay.

Is the resistance between 15 and 25 Ohms?

Yes

- Go To 4

No

- Replace the Intake Air Heater relay.
- Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test

4. SIGNAL CIRCUIT OPEN FROM RELAY TO ECM

Disconnect the ECM harness connectors.

Check connectors - Clean/repair as necessary.

Measure the resistance of the intake air heater relay signal circuit between the ECM connector and the intake air heater relay connector.

Is the resistance less than 10 Ohms?

Yes

- Go To 5

No

- Repair the open signal circuit from PDC to ECM harness connector.
- Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test

5. SIGNAL CIRCUIT SHORTED TO BATTERY NEGATIVE

Measure the voltage between the signal circuit of the intake air heater relay and battery negative.

Is the voltage greater than 1 volts?

Yes

- Repair the signal circuit shorted to Battery negative.
- Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test

No

- Go To 6

6. ECM

Reconnect the ECM harness connectors.

Disconnect the intake air heater relay signal wire and use a jumper to connect it to battery negative.

Turn the ignition on.

With the scan tool, read DTCs.

Did DTC P0542 set?

Yes

- Refer to the INTERMITTENT CONDITION Diagnostic Procedure. Intermittent Condition

No

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