2010 Cadillac Truck SRX AWD V6-2.8L Turbo Page 1390

2010 Cadillac Truck SRX AWD V6-2.8L Turbo Page 1390

* 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.

DTC Descriptors

DTC P0449

- Evaporative Emission (EVAP) Vent Solenoid Control Circuit

DTC P0498

- Evaporative Emission (EVAP) Vent Solenoid Valve Control Circuit Low Voltage

DTC P0499

- Evaporative Emission (EVAP) Vent Solenoid Valve Control Circuit High Voltage

Diagnostic Fault Information

Circuit/System Description

The evaporative emission (EVAP) canister vent valve is used for EVAP system diagnostics. The EVAP canister vent valve is a normally open

valve. Battery positive voltage is supplied directly to the EVAP canister vent valve. The engine control module (ECM) controls the solenoid by

grounding the control circuit with a solid state device called a driver. The driver is equipped with a feedback circuit that is pulled-up to a voltage.

The ECM can determine if the control circuit is open, shorted to ground, or shorted to a voltage by monitoring the feedback voltage. If the ECM

detects the control circuit voltage is within a predetermined range when the circuit is commanded OFF, this DTC sets.

Conditions for Running the DTC

* The engine speed is greater than 80 RPM.

* The ignition voltage is between 10-18 volts.

* The ECM has commanded the EVAP canister vent valve ON and OFF at least once during the ignition cycle.

* The DTCs runs continuously once the above conditions are met.

Conditions for Setting the DTC

P0449

The ECM detects the voltage on the EVAP canister vent valve control circuit is between 2.6-4.6 volts when the driver is commanded OFF. The

condition exists for less than 4 seconds or for a cumulative of 30 seconds.

P0498

The ECM detects the voltage on the EVAP canister vent valve control circuit is less than 2.6 volts when the driver is commanded OFF. The

condition is present for greater than 4 seconds or for a cumulative of 30 seconds.

P0499

The ECM detects the voltage on the EVAP canister vent valve control circuit is greater than 4.6 volts when the driver is commanded ON. The

condition is present for greater than 4 seconds or for a cumulative of 30 seconds.

Action Taken When the DTC Sets

* DTC P0449, P0498 and P0499 are Type B DTCs.

* The EVAP system will only purge during open loop.

Conditions for Clearing the DTC

DTC P0449, P0498 and P0499 are Type B DTCs.