Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Circuit/System Testing
2008 Pontiac Grand Prix BaseSECTION Circuit/System Testing
WARNING: This page is about a different car, the 2008 Buick LaCrosse and 2008 Buick Allure. However, it is still accessible from the selected car via links, so may be relevant.
IMPORTANT:
- Larger volume fuel tanks and/or those with lower fuel levels may require several minutes for the floating indicator to stabilize.
- Refer to the J 41413-200 operation manual for detailed instructions in Evaporative Emission System Diagnosis .
- Connect the J 41413-200 to the vehicle EVAP service port. For vehicles without a service port, disconnect the purge tube at the quick connector on the EVAP canister side of the purge solenoid valve and install the CH-48096 .
- Use a scan tool to seal the EVAP system.
- Use the flow meter on the J 41413-200
, calibrated to 0.51 millimeter (0.020 inch) to determine that there is no leak in the EVAP system.
- If a leak is detected, use the J 41413-200 to apply smoke to the EVAP system at the service port or the purge tube until the leak is located using the J 41413-SPT .
- To test for a restriction in the purge path connect the GE-41415-50 to the J 41413-200 then connect the adapter to the filler neck.
- Allow the engine to idle.
- Use the Purge/Seal function to seal the system with a scan tool.
- Command the EVAP canister purge solenoid valve to 30 percent.
- The vacuum/pressure gage on the J 41413-200
and the FTP parameter on the scan tool should both show vacuum.
- If the vacuum/pressure gage shows vacuum, but the FTP parameter does not show vacuum, replace the FTP sensor.
- If neither the FTP parameter nor the vacuum/pressure gage shows vacuum, repair the restriction in the purge path. Refer to Evaporative Emissions Hose Routing Diagram .
- Verify that the vacuum increases to the abort limit on the scan tool or more than 3.2 volts, and the values are similar between the scan tool and the vacuum/pressure gage on the J 41413-200
.
- If the values are not similar, or the voltage did not reach 3.2 volts, replace the FTP sensor.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.