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HOMESERVICE MANUALSGMC1999FORWARD CONTROL 5.7 R, AUTOMATICREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 181 (ENGINE CONTROLS - SELF-DIAGNOSTICS - 2.2L)DIAGNOSTIC TESTSDTC P0442: EVAP SYSTEM - SMALL LEAK DETECTEDDIAGNOSTIC PROCEDURES
1999 GMC Forward Control 5.7 R, Automatic

Diagnostic Procedures

1999 GMC Forward Control 5.7 R, AutomaticSECTION Diagnostic Procedures
WARNING: This page is about a different car, the 2003 Saturn Vue. However, it is still accessible from the selected car via links, so may be relevant.
  1. Perform diagnostic system check - engine controls. See DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS  under SELF-DIAGNOSTIC SYSTEM. After performing diagnostic system check - engine controls, go to next step.
    2. NOTE: Larger volume fuel tanks and/or those with lower fuel levels may require several minutes to stabilize.
  2. Turn the nitrogen/smoke valve to nitrogen. Connect the nitrogen/smoke hose to the 0.20" (0.5 mm) test orifice on the bottom front of the Evaporative Emissions System Tester (J-41413-200). Use the remote switch to activate the J-41413-200. Align the Red flag on the flow meter with the floating indicator. Use the remote switch to de-activate the J-41413-200. Install the Fuel Tank Cap Adapter (J-41415-40) to the fuel fill pipe. Remove the nitrogen/smoke hose from the test orifice and install the hose onto the J-41415-40. Turn ignition on, with engine off. Command the EVAP vent solenoid CLOSED with a scan tool. Use the remote switch to introduce nitrogen and fill the EVAP system until the floating stabilizes. Compare the flow meter's stable floating indicator position to the Red flag. Is the floating indicator below the Red flag? If yes, go to DIAGNOSTIC AIDS . If no, go to next step.
    3. NOTE: Ensure that vehicle underbody temperature is similar to the ambient temperature and allow the surrounding air to stabilize before starting the diagnostic procedure. System flow will be less with higher temperatures.
  3. Turn ignition off. Connect the Evaporative Emissions System Tester (J-41413-200) power supply clips to a known-good 12-volt source. Install the Fuel Tank Cap Adapter (J-41415-40) to the fuel fill pipe. Connect the fuel fill cap to the J-41415-40. Connect the J-41413-200 nitrogen/smoke supply hose to the J-41415-40. Turn ignition on, with engine off. Command the EVAP vent solenoid closed with a scan tool. Turn the nitrogen/smoke valve on the J-41413-200 control panel to SMOKE. Use the remote switch to introduce smoke into the EVAP system. Use the EVAP Service Port Vent Fitting (J-41413-VLV) to open the EVAP service port. Remove the J-41413-VLV once smoke is observed. Continue to introduce smoke into the EVAP system for an additional 60 seconds. Inspect the entire EVAP system for exiting smoke with the High Intensity White Light (J-41413-SPT). Continue to introduce smoke at 15 second intervals until the leak source has been located. Did you locate and repair a leak source? If yes, go to step  5. If no, go to next step.
  4. Disconnect the J-41415-40 from the fuel fill pipe. Install the fuel fill cap to the fuel fill pipe. Connect the J-41413-200 nitrogen/smoke supply hose to the EVAP service port. Use the remote switch to introduce smoke into the EVAP system. Inspect the entire EVAP system for exiting smoke with the J-41413-SPT. Continue to introduce smoke at 15 second intervals until the leak source has been located. Did you locate and repair a leak source? If yes, go to next step. If no, go to DIAGNOSTIC AIDS .
    5. NOTE: Larger volume fuel tanks and/or those with lower fuel levels may require several minutes for the floating indicator to stabilize.
  5. Turn the nitrogen/smoke valve to nitrogen. Connect the nitrogen/smoke hose to the 0.20" (0.5 mm) test orifice on the bottom-front of the J-41413-200. Use the remote switch to activate the J-41413-200. Align the Red flag on the flow meter with the floating indicator. Use the remote switch to de-activate the J-41413-200. Install the J-41415-40 to the fuel fill pipe. Remove the nitrogen/smoke hose from the test orifice and install the hose onto the J-41415-40. Turn ignition on, with engine off. Command the EVAP vent solenoid closed with a scan tool. Use the remote switch to introduce nitrogen and fill the EVAP system until the floating stabilizes. Compare the flow meter's stable floating indicator position to the Red flag. Is the floating indicator below the Red flag? If yes, go to next step. If no, go to step  2.
  6. With a scan tool, observe the stored information, Capture Info. Does the scan tool display any DTCs that you have not diagnosed? If yes, see DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no, system is okay.
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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.