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 and the Intake Air Heater Relay is commanded ON.
- Set Condition:
With the Intake Air Heater Relay commanded on, the Powertrain Control Module (PCM) is not reading any 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, read DTCs.
Did the DTC return?
Yes
- Go To 2
No
- Perform the INTERMITTENT CONDITION diagnostic procedure. Intermittent Condition Test
2. CHECK THE (K174) INTAKE AIR HEATER RELAY CONTROL CIRCUIT
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 on, engine not running.
2. Disconnect the (K174) Intake Air Heater Relay Control circuit connector at the Intake Air Heater Relay.
3. Using a scan tool, actuate the Cold Start Aid Driver 1 Output circuit.
NOTE: Set the actuation to on.
4. Using a voltmeter, probe the (K174) Intake Air Heater Relay Control circuit at the connector.
Does the voltmeter read equivalent to battery voltage?
Yes
- Go To 4
No
- Go To 3
3. CHECK THE (K174) INTAKE AIR HEATER RELAY CONTROL CIRCUIT FOR AN OPEN/HIGH RESISTANCE
1. Turn ignition off.
2. Disconnect the PCM C2 harness connector.
3. Measure the resistance of the (K174) Intake Air Heater Relay Control circuit between the Intake Air Heater Relay and the PCM C2 harness connector.
Is the resistance below 5.0 Ohms?
Yes
- Replace the Powertrain Control Module.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.
No
- Repair the (K174) 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 CIRCUIT
1. Turn ignition off.
2. Disconnect the (K974) Intake Air Heater Relay Control Return circuit connector at the Intake Air Heater Relay.
3. Using a voltmeter connected to battery positive, probe the (K974) Intake Air Heater Relay Control Return circuit at the connector.
Does the voltmeter read equivalent to battery voltage?
Yes
- Replace the Intake Air Heater Relay.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.
No
- Go To 5
5. CHECK THE (K974) INTAKE AIR HEATER RELAY CONTROL RETURN FOR AN OPEN/HIGH RESISTANCE
1. Disconnect the PCM C2 harness connector.
2. Measure the resistance of the (K974) Intake Air Heater Relay Control Return circuit between the Intake Air Heater Relay connector and the PCM C2 harness connector.
Is the resistance below 5.0 Ohms?
Yes
- Repair the (K974) Intake Air Heater Relay Control Return circuit for an open or high resistance.
- 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.