P2609
P2609-INTAKE AIR HEATER SYSTEM PERFORMANCE
For a complete wiring diagram, refer to the Wiring Information.
Theory of Operation
Heating the inlet air during cold temperatures will increase the fuel efficiency and improves system performance. An Intake Air Heater is used for this purpose. The Intake Air Heater works in two phases, preheat phase (before engine starts) and post heat phase (after engine starts). Preheat phase typically heats the Intake Air Heater coil during the key-on for about 10 seconds to 30 seconds depending on inlet air temperature. The PCM controls Intake Air Heater operation with the Intake Air Heater Relay, which is located directly behind the air filter box under the fresh air hose. The Intake Air Heater Relay is not a typical type of relay due to the amount of current passing through it. The Intake Air Heater Relay visually resembles a solenoid in appearance. The Intake Air Heater monitor looks for a change in battery voltage as the heater is turned on and off during preheat, to indicate proper operation. The Intake Air Heater performance DTC is a two trip fault. The PCM will turn off the MIL lamp when the monitor runs and passes in 4 consecutive drive cycles.
- When Monitored:
During the preheat cycle, while the wait to start lamp is illuminated.
- Set Condition:
The Powertrain Control Module (PCM) monitors the battery system voltage and looks for a calibrated drop when the Intake Air Heater is commanded on. The fault is set if the PCM detects a voltage difference below the calibrated value when the Intake Air Heater circuit is commanded on and off during the preheat cycle at key on.
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Pre-Diagnostic Troubleshooting Procedure.
Diagnostic Test
1. ACTIVE DTC
1. Ignition on, engine not running.
2. With the scan tool check for active DTCs.
Is the DTC active?
Yes
- Go To 2
No
- Perform the INTERMITTENT CONDITION - 6.7L diagnostic procedure. Intermittent Condition Test
2. CHECK THE (A19) AUXILIARY BATTERY CIRCUIT FOR AN OPEN/HIGH RESISTANCE
NOTE: A loose or poor Battery Ground Cable connection may cause this code to set.
1. Turn ignition on.
2. Using a voltmeter, probe the (A19) Auxiliary Battery circuit at the Intake Air Heater Relay terminal.
NOTE: It is important for the circuit to be connected and carrying a load during testing. For best results, do not disconnect the circuit at any time during this test procedure.
3. Using a scan tool, actuate the Cold Start Aid Driver 1 Output circuit. NOTE: Set the actuation to toggle.
4. Monitor the reading on the voltmeter while the Intake Air Heater circuit is toggling on and off. Monitor the circuit and let the actuation run until it times out.
NOTE: The meter should read equivalent to battery voltage during the entire actuation.
Does the voltmeter read as described in the note above?
Yes
- Go To 3
No
- Repair the (A19) Auxiliary Battery circuit for an open or high resistance. If the Fusible Link is found to be blown, check for a short to ground on the entire (A19) Auxiliary Battery circuit and (A58) Intake Air Heater circuit.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.
3. CHECK THE INTAKE AIR HEATER RELAY
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. Move the voltmeter to the (A58) Intake Air Heater circuit terminal on the Intake Air Heater Relay terminal.
2. Using a scan tool, actuate the Cold Start Aid Driver 1 Output circuit.
NOTE: Set the actuation to toggle.
3. Monitor the reading on the voltmeter while the Intake Air Heater circuit is toggling on and off. Monitor the circuit and let the actuation run until it times out.
NOTE: The meter should read equivalent to battery voltage when the circuit is toggled on, and near zero volts when the circuit is toggled off.
Does the voltmeter read as described in the note above?
Yes
- Go To 4
No
- Replace the Intake Air Heater Relay.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.
4. CHECK THE (A58) INTAKE AIR HEATER CIRCUIT FOR AN OPEN/HIGH RESISTANCE
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. Move the voltmeter to the (A58) Intake Air Heater circuit connection at the Intake Air Heater.
2. Using a scan tool, actuate the Cold Start Aid Driver 1 Output circuit. NOTE: Set the actuation to toggle.
3. Monitor the reading on the voltmeter while the Intake Air Heater circuit is toggling on and off. Monitor the circuit and let the actuation run until it times out.
NOTE: The meter should read equivalent to battery voltage when the circuit is toggled on, and near zero volts when the circuit is toggled off.
Does the voltmeter read as described in the note above?
Yes
- Replace the Intake Air Heater.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.
No
- Repair the (A58) Intake Air Heater circuit for an open or high resistance.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.