Circuit/System Testing
WARNING: This page is about a different car, the 2019 Chevrolet Malibu. However, it is still accessible from the selected car via links, so may be relevant.
NOTE:
Ensure that the vehicle underbody temperature is similar to the ambient temperature and allow the surrounding air to stabilize before starting the diagnostic procedure.
- Vehicle in Service Mode.
- Verify the following scan tool parameters when commanding the EVAP Test ON.
- The EVAP Leak Detection Pump Command should show ON.
- The EVAP Leak Detection Pump Switching Valve Command should change from Venting to Not Venting.
- If not within specified range
Replace the Q63 Evaporative Emission System Leak Detection Pump Assembly
- Go to next step: If within specified range
- Verify and record the EVAP leak detection pump pressure and fuel tank pressure. Both pressures should drop
- If status changes, but no pressure drop
- Remove the vent pipe and the fresh air pipe from the EVAP leak detection pump assembly
- Verify the pump openings for any of the conditions listed below
- The EVAP leak detection pump to the vent solenoid tube and clamps for damage or restriction
- Missing or damaged EVAP leak detection pump O-rings
- The fresh air tube near the fuel fill pocket for a restriction
- The fresh air tube for a restriction
Repair or replace any of the above components.
- Go to next step: If all components test normal
Go to next step: Replace the Q63 Evaporative Emission System Leak Detection Pump Assembly.