P0487

P0487-EGR AIRFLOW THROTTLE CONTROL CIRCUIT A OPEN





For a complete wiring diagram Refer to Diagrams/Electrical.

Theory of Operation


The EGR Airflow Throttle is a smart device that is commanded by the ECM through a PWM signal. This is a completely modulated device. When feedback does not match commanded for more than 2 seconds this algorithm fails. The ECM will light the MIL lamp immediately after this diagnostic runs and fails. During this time the EGR Airflow Throttle is disabled and goes to the fully open position (if possible). Active Aftertreatment regenerations make take longer if this condition exists. The ECM will turn off the MIL lamp after the diagnostic runs and passes in 4 consecutive drive cycles.

- When Monitored:
Ignition on

- Set Condition:
Status line feedback voltage is outside of a calibratable range







Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Initial Inspection and Diagnostic Overview


Diagnostic Test


1. DTC P0487 ACTIVE
Ignition on, engine not running.
With the scan tool, read DTCs.
Is DTC P0487 active?

Yes


- Go To 2


No


- Refer to the INTERMITTENT CONDITION - DIESEL Symptom. Intermittent Condition



2. OPEN AIRFLOW CONTROL VALVE TTVA MOTOR (-) CIRCUIT




Turn the ignition off.
Disconnect the EGR Airflow control valve harness connector.
Disconnect the ECM harness connector.

NOTE: Check connectors - Clean/repair as necessary.

Measure the resistance of the (K158) TTVA motor (-) circuit from the EGR Airflow control valve harness connector to the ECM harness connector.
Is the resistance less than 10 ohms?

Yes


- Go To 3


No


- Repair/replace open circuit in the engine harness.
- Perform POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test



3. SHORTED AIRFLOW CONTROL VALVE (K158) TTVA MOTOR (-) CIRCUIT




Measure the resistance between the EGR Airflow Control Valve (K158) TTVA motor (-) circuit at the ECM harness connector and ground
Is the resistance greater than 100k ohms?

Yes


- Go To 4


No


- Repair/replace short circuit to ground in the engine harness.
- Perform POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test



4. AIRFLOW CONTROL VALVE (K158) TTVA MOTOR (-) CIRCUIT SHORTED TO ANOTHER CIRCUIT




Measure the resistance between the EGR Airflow Control Valve (K158) TTVA motor (-) circuit in the ECM harness connector and all other circuits.
Is the resistance greater than 100k ohms?

Yes


- Go To 5


No


- Repair or replace the harness.
- Perform POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test



5. THROTTLE BODY
Measure resistance from (F348) smart power relay feed circuit to (K314) TTVA motor (+) circuit.
Is resistance 750 ohms (+/- 15%)

Yes


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


No


- Replace the EGR Airflow control valve.
- Perform POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test