2010 Cadillac CTS Sedan AWD V6-3.6L Page 1463
3. Engine Idling, observe the DTC information with a scan tool. DTC P0449, P0498, or P0499 should not set.
4. Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not reset. You may also operate the vehicle within the
conditions that you observed from the Freeze Frame/Failure Records data.
Circuit/System Testing
1. Ignition OFF, disconnect the X-420 harness connector at the rear of the fuel tank.
2. Ignition ON, verify that a test lamp illuminates between the ignition voltage circuit terminal J and ground.
瀚慖f the test lamp does not illuminate, test the ignition voltage circuit for a short to ground or an open/high resistance. If the circuit tests
normal and the ignition voltage circuit fuse is open, test all components connected to the ignition voltage circuit and replace as necessary.
3. Ignition OFF, connect a test lamp between the control circuit terminal D and the ignition voltage circuit terminal J.
Note: The control circuit for the EVAP vent solenoid valve is pulled-up to voltage within the ECM, 2.6-4.6 V on the control circuit is
normal.
4. Ignition ON, use a scan tool to command the EVAP vent solenoid valve ON and OFF. The test lamp should turn ON and OFF.
瀚慖f the test lamp remains ON all the time, test the control circuit for a short to ground. If circuit/connections test normal, replace the ECM.
瀚慖f the test lamp remains OFF all the time, test the control circuit for a short to voltage or an open/high resistance. If circuit/connections
test normal, replace the ECM.
5. Test for 2.6-4.6 V between the control circuit terminal D and ground.
瀚慖f not within the specified range, replace the ECM.
6. Remove the EVAP canister. Refer to Evaporative Emission Canister Replacement (See: Powertrain Management/Emission Control
Systems/Evaporative Emissions System/Evaporative Emission Control Canister/Service and Repair).
7. Inspect the EVAP vent solenoid valve circuits in the fuel tank harness, between the EVAP vent solenoid valve connector and X-420 for the
following conditions, and repair as necessary:
* Damaged wiring or terminals
* Open circuits
* Short to ground
* Wire to wire short
8. If all circuits/connections test normal, test or replace the EVAP vent solenoid valve.
Component Testing
1. Test for 20-24 ohm between the terminals of the EVAP vent solenoid valve.
瀚慖f not within the specified range, replace the EVAP vent solenoid valve.
2. Measure the resistance between each terminal of the EVAP vent solenoid valve and the EVAP vent solenoid valve housing. The DMM
should display OL.
瀚慖f not the specified value, replace the EVAP vent solenoid valve.
Repair Instructions
Perform the Diagnostic Repair Verification (See: Verification Tests) after completing the diagnostic procedure.
* Evaporative Emission Canister Vent Solenoid Valve Replacement (See: Powertrain Management/Emission Control Systems/Evaporative
Emissions System/Evaporative Emission Control Canister/Canister Vent Valve/Service and Repair)
* Control Module References (See: Testing and Inspection/Programming and Relearning) for ECM replacement, setup, and programming
P0499
DTC P0449, P0498, or P0499 (w/LLT)
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic System
Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Strategy Based Diagnosis) for an
overview of the diagnostic approach.
* Diagnostic Procedure Instructions (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic Procedure
Instructions) provides an overview of each diagnostic category.
