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Diagnostic Aids

WARNING: This page is about a different variant/trim than selected.

Perform this test when instructed during QUICK TEST  or if directed by other test procedures. This test is used to diagnose the following:

Fig 1: EVAP Components Using Purge Flow System
G95I12607
Fig 2: EVAP Components Using Vapor Management System
G95D27220
Fig 3: CANP Solenoid Test Circuit & Connector Terminals
G95I35996
Fig 4: Purge Flow Test Circuit & Connector Terminals
G95A35998
  1. 1) DTC P0443: Check VPWR Circuit Voltage  Disconnect canister purge solenoid wiring harness connector. Turn ignition on. Measure voltage between VPWR terminal of canister purge solenoid wiring harness connector and battery ground. If voltage is 10.5 volts or more, go to next step. If voltage is less than 10.5 volts, repair open in VPWR circuit and repeat QUICK TEST .
  2. 2) Check Component Resistance  Turn ignition off. Leave canister purge solenoid wiring harness connector disconnected. Measure resistance between canister purge solenoid terminals. If resistance is 30-90 ohms, go to next step. If resistance is not as specified, replace canister purge solenoid. Reconnect any disconnected components and go to step 42).
  3. 3) Check CANP Solenoid For Internal Short  Turn ignition off. Leave wiring harness connector disconnected. Measure resistance between each solenoid terminal and canister purge solenoid housing. If each resistance measurement is more than 90 ohms, canister purge solenoid is okay. Go to next step. If resistance is not as specified, replace canister purge solenoid. Reconnect any disconnected components and go to step 42).
  4. 4) Check EVAP Canister Purge Circuit Continuity  Leave ignition off and canister purge solenoid wiring harness connector disconnected. Disconnect PCM wiring harness connector. Inspect pins for damage and repair as necessary. Install EEC-V Breakout Box (014-000950), leaving PCM disconnected. Measure resistance between test pin No. 67 at breakout box and EVAP canister purge terminal of solenoid wiring harness connector. If resistance is less than 5 ohms, go to next step. If resistance 5 ohms or more, repair open circuit and repeat QUICK TEST .
  5. 5) Check Circuit For Short To PWR GND  Leave ignition off. Disconnect scan tester from DLC (if applicable). Measure resistance between test pin No. 67 and test pins No. 24 and 103. If each resistance is more than 10,000 ohms, go to step 22). If resistance is 10,000 ohms or less, repair EVAP canister purge circuit short to PWR GND circuit. Clear PCM memory and repeat QUICK TEST .
    NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 5) to step 7). No test procedures have been omitted.
  6. 7) DTC P1443: Check Purge Flow Sensor (PFS)  Connect scan tester to Data Link Connector (DLC). Start engine and allow to idle. Disconnect PFS wiring harness connector. Inspect connector for damage and repair if necessary. Reconnect PFS wiring harness connector. Using scan tester, access PF PID. If voltage fluctuates about 0.9-1.1 volts, go to step 19). If voltage fluctuates 2.3-2.6 volts, go to step 18). If voltage does not fluctuate as specified, go to next step.
  7. 8) Visual Check Of Evaporative Emission System  Check for kinked or pinched fuel vapor tubes/hoses between EVAP canister, EVAP canister purge valve and engine intake manifold. Check for cracked or smashed EVAP canister. If a problem is found, repair as necessary. After repairs, go to step 42). If no problem is found, go to step 11).
    NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 8) to step 11). No test procedures have been omitted.
  8. 11) Check EVAP Canister  Disconnect fuel vapor hose to EVAP canister purge valve at EVAP canister. Check for contamination or blockages at all ports on EVAP canister (to the fuel tank, to the EVAP canister purge valve and to the atmosphere). If a problem is found, repair as necessary. After repairs, go to step 42). If no problem is found, go to step 12).
  9. 12) Check For Fuel Vapor Hose Leak  Disconnect the fuel vapor hose from EVAP canister purge valve. Plug open end of fuel vapor hose at EVAP canister. Install a hand vacuum pump to open end of fuel vapor hose at EVAP canister purge valve. Apply 16 in. Hg (53 kPa) of vacuum with vacuum pump. If the vacuum pump holds the vacuum, remove plug in hose and to next step. If vacuum pump does not hold vacuum, replace damaged fuel vapor hose, reconnect any disconnected components and go to step 42).
  10. 13) Check For Fuel Vapor Hose Blockage  Disconnect the fuel vapor hose from EVAP canister purge valve. Install a hand vacuum pump to open end of fuel vapor hose at EVAP canister purge valve. Apply 16 in. Hg (53 kPa) of vacuum with vacuum pump. If the vacuum pump holds vacuum, remove the vacuum pump, and repair or straighten fuel vapor hose. After repair, reconnect any disconnected components and go to step 42). If the vacuum pump does not hold vacuum, remove vacuum pump. Reconnect fuel vapor hose at EVAP canister. Leave other end of fuel vapor hose disconnected at EVAP canister purge valve. Go to step 17).
    NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 13) to step 17). No test procedures have been omitted.
  11. 17) Check VPWR To EVAP Canister Purge Valve  Disconnect EVAP canister purge valve harness connector. Turn ignition on, engine off. Measure VPWR circuit voltage between EVAP canister purge valve harness connector and battery negative post. Turn ignition off. If voltage was more than 10.5 volts, go to next step. If voltage was not more than 10.5 volts, repair open in VPWR circuit to canister purge valve. Reconnect any disconnected components. Clear PCM memory and repeat QUICK TEST .
  12. 18) Check EVAP Canister Purge Valve Stuck Open Or PFS Damage  Disconnect fuel vapor hose from intake manifold at PFS. Reconnect the EVAP canister purge valve harness connector. Install a hand-held vacuum pump to intake manifold side of PFS. Apply 16 in. Hg (53 kPa) of vacuum to open end of PFS. If the EVAP canister purge valve-PFS assembly holds vacuum for 20 seconds, leave the vacuum pump connected. Go to next step. If the EVAP canister purge valve-PFS assembly does not hold vacuum for 20 seconds, repair as necessary. If PFS housing is cracked, replace PFS. Otherwise, replace fuel vapor hose between EVAP canister purge valve and PFS. If fuel vapor hose was okay, replace EVAP canister purge valve. Reconnect any disconnected components. Go to step 42).
  13. 19) Check EVAP Canister Purge Valve Stuck Closed  Connect scan tool to DLC connector. Using vacuum pump, apply 16 in. Hg (53 kPa) of vacuum to open end of PFS. Key on, engine off. Access Output Test Mode on the scan tool and cycle EVAP canister purge valve on and off. Turn ignition off. If the EVAP canister purge valve opened and vacuum reading on the vacuum pump dropped (air passes freely) when commanding the output on, remove vacuum pump and go to next step. If the EVAP canister purge valve opened and vacuum reading on the vacuum pump did not drop (air does not pass freely) when commanding the output on, remove the vacuum pump. Repair blockages in fuel vapor hose between EVAP canister purge valve and PFS. If fuel vapor hose is okay, replace EVAP canister purge valve. Reconnect any disconnected components and go to step 42).
  14. 20) Check Intake Manifold Vacuum To PFS  Install a vacuum gauge to the open end of fuel vapor hose (intake manifold side) at PFS. Start engine. Observe vacuum gauge at idle. Turn ignition off. If the vacuum gauge reading was greater than 10 in. Hg (33.77 kPa) with engine running, check for small vacuum leaks between PFS and intake manifold. Repair as necessary. Reconnect any disconnected components. Drive vehicle, then go to step 42). If the vacuum gauge reading was not greater than 10 in. Hg (33.77 kPa) with engine running, repair blockage, reconnect loose fuel vapor hose or replace cracked, split fuel vapor hose between the PFS and intake manifold. After repairs, go to step 42). If DTC P1443 is still present, go to next step.
  15. 21) Check EVAP Canister Purge Valve Resistance  Disconnect EVAP canister purge valve. Measure EVAP canister purge valve resistance. If the resistance is 30-90 ohms, go to next step. If the resistance is not 30-90 ohms, replace damaged EVAP canister purge valve. Reconnect any disconnected components. Go to step 42).
  16. 22) Check EVAP Canister Purge Circuit For Short To VPWR  Install breakout box, leave PCM disconnected. Measure resistance between PCM test pin 67 and PCM test pin 71. If resistance is greater than 10,000 ohms, replace the PCM. Reconnect any disconnected components. Access the EVAPPDC PID on the scan tool. Drive vehicle (including a steady accelerator speed over 50 mph until the EVAPPDC PID shows 75 percent duty cycle). Then maintain approximate speed until duty cycle reaches zero percent. After additional two minutes driving, bring vehicle to an idle. Repeat QUICK TEST . If resistance is not greater than 10,000 ohms, repair short circuit. Reconnect any disconnected components. Clear PCM memory. Access the EVAPPDC PID on the scan tool. Drive vehicle (including a steady accelerator speed over 50 mph until the EVAPPDC PID shows 75 percent duty cycle). Then maintain approximate speed until duty cycle reaches zero percent. After additional two minutes driving, bring vehicle to an idle. Repeat QUICK TEST .
  17. 23) Check EVAP Leak Through EVAP Service Port  Remove atmospheric vent cap (blue or black) on EVAP canister vent line. Plug (or tape) open vent on EVAP canister. Disconnect and plug fuel vapor hose to PFS (or EVAP canister purge valve) from intake manifold at the intake manifold vacuum source. Locate evaporative emission test port (marked EVAPORATIVE SERVICE PORT) between EVAP canister purge valve and EVAP canister. If vehicle does not have a test port, next step. Access the Rotunda Evaporative Emission System Tester (134-00056), including the compressed gas source (nitrogen or argon) and pressure regulator. Perform a Tester Self-Test using the instructions provided with the Tester Kit. Regulate the gas pressure on the Tester to 27 in. H2O (6.74 kPa). Install the Rotunda Evaporative Emission System Tester to the test port and follow the system leak test instructions provided with the Tester Kit. If the pressure is not 26-28 in. H2O (6.46-6.97 kPa), use the ultra-sonic leak detector provided with the Tester Kit to check for leakage at the vehicle's fuel filler cap and filler pipe assembly. If a leak is indicated, remove and verify fuel filler cap according to original equipment specifications. Replace damaged fuel filler cap. Reinstall fuel filler cap and tighten cap only one eighth turn so that cap initially clicks by sound or touch. Repeat evaporative emission system leak test using Tester. If the leak is still present, repair or replace fuel tank, fuel filler pipe, fuel vapor valve or fuel vapor hose between fuel tank and EVAP canister as necessary. Reconnect any disconnected components. Verify a symptom no longer exists. If a leak is not indicated, go to next step.
  18. 24) Check EVAP System Using Rotunda EVAP System Tester  Remove the fuel filler cap. Install the Rotunda Evaporative Emission System Tester (134-00056), including the compressed gas (nitrogen or argon) and pressure regulator. Tester kit contains all required adapters (Schrader valve and fuel filler cap per vehicle application). Turn ignition on, engine off. Pressurize the vehicle evaporative emission system at 27 in. H2O (6.74 kPa) using the Evaporative Emission System Tester and the instructions that come with the tester. If a system leak is indicated by the tester red light on, allow the two-position control on the tester to provide a continuing flow of the gas to the closed evaporative emission system. Maintain 27 in. H2O (6.74 kPa) pressure on the system (monitor tester pressure gauges). Go to next step. If a system leak is not indicated by the tester, remove the Evaporative Emission System Leak Tester. Clear PCM memory to clear DTCs. Access the EVAPPDC PID on the scan tool. Drive vehicle (including a steady accelerator speed over 50 mph until the EVAPPDC PID shows 75 percent duty cycle). Then maintain approximate speed until duty cycle reaches zero percent. After an additional two minutes driving, bring vehicle to an idle. Repeat QUICK TEST . VERIFY a symptom no longer exists.
  19. 25) Check For Fuel Vapor Hose Restrictions  Turn ignition on, engine off. Disconnect and plug the fuel vapor hose from the EVAP canister at EVAP canister purge valve. Reinitiate pressurizing of vehicle evaporative emission system using the Rotunda Evaporative Emission System Tester. See step 24) for pressurizing instructions. When pressure on the evaporative emission system is stabilized close to 27 in. H2O (6.74 kPa), record the reading. Remove the plug at the fuel vapor hose to EVAP canister at the EVAP canister purge valve. Observe pressure gauges on tester. If the pressure drops immediately, remove plugs. Reinstall the dust cap (blue or black) on EVAP canister or canister vent line at canister. Reconnect any disconnected components and go to step 42). If pressure does not immediately drop, remove blockages and straighten fuel vapor tubes/hoses between fuel tank, EVAP canister purge valve and EVAP canister. After repairs, remove plugs. Reinstall the dust cap (blue or black) on EVAP canister. Reconnect any disconnected components and go to step 42).
    Fig 5: PFS Sensor Connector Terminals
    G95I27233
    NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 25) to step 27). No test procedures have been omitted.
  20. 27) DTC P1444: Check PFS Low Voltage To PCM  Disconnect PFS harness connector. Check for loose pins or broken wires by pulling moderately on the VPWR circuit at PFS harness connector. Repair as necessary. Reconnect PFS harness connector. Connect scan tool. Turn ignition on, engine running. Access EVAPPF PID (PFS input range to the PCM is 0.40-4.80 volts). Turn ignition off. If EVAPPF PID voltage was less than 0.40 volt; for EVAPPF PID voltage between 0.20 and 0.40 volt, go to next step. For EVAPPF PID voltage less than 0.20 volt, go to step 30). If voltage is not less than 0.40 volt, fault is an intermittent DTC P1444. Go to step 32).
  21. 28) Check For Open PFS VPWR Circuit  Disconnect PFS harness connector. Allow the vehicle and PFS to cool down or warm up to room temperature, 55-80°F (13-27°C), before taking a resistance measurement on the PFS. This can take 15 to 20 minutes. Measure resistance between VPWR pin and PF, PWR GND pins on the PFS. See Fig 6. If resistance is greater than 160 ohms between VPWR and PF pins or greater than 190 ohms between VPWR and PWR GND pins, replace damaged PFS. Reconnect any disconnected components. Record data from this test step and go to step 42). If resistance is not greater than 160 ohms between VPWR and PF pins or not greater than 190 ohms between VPWR and PWR GND pins, go to next step.
    Fig 6: PFS Connector Terminal Identification
    G95I27233
  22. 29) Check VPWR Circuit For Open  Install breakout box, leave PCM disconnected. Measure resistance of VPWR circuit between PCM test pin 71 and PFS harness connector. If resistance is less than 5.0 ohms, leave breakout box installed. For DTC P1444, go to step 30). For DTC P1445, go to step 34). If resistance is not less than 5.0 ohms, repair open circuit. Reconnect any disconnected components and verify a symptom no longer exists. Clear PCM memory and repeat QUICK TEST .
  23. 30) Check For Short To PWR GND Circuit In PFS  Disconnect PFS harness connector. Allow the vehicle and PFS to cool down or warm up to room temperature, 55-80°F (13-27°C), before taking a resistance measurement on the PFS. This can take 15 to 20 minutes. Measure resistance between PWR GND and PF pins on the PFS. See Fig 6. If resistance is less than 25.50 ohms, replace damaged PFS. Reconnect any disconnected components and go to step 42). If resistance is not less than 25.50 ohms, go to next step.
  24. 31) Check PF Circuit For Short To PWR GND  Install breakout box, leave PCM disconnected. Disconnect scan tool from DLC. Measure resistance between PCM test pin 11 and PCM test pins 24 and 103. If both resistances are greater than 10,000 ohms, replace damaged PCM. Reconnect any disconnected components and repeat QUICK TEST . If both resistances are greater than 10,000 ohms, repair short circuit. Reconnect any disconnected components. Clear PCM memory and repeat QUICK TEST .
  25. 32) Check PFS Circuit For Intermittent VPWR Open Or PWR GND Short  Turn ignition on, engine off. Using scan tool, access EVAPPF PID. Observe EVAPPF PID for an indication of a fault while performing the following: Lightly tap on PFS; wiggle PFS connector and harness between sensor and PCM. A fault is indicated by a sudden change in EVAPPF PID voltage (less than 0.14 volt). If a fault is indicated, isolate fault and repair as necessary. Reconnect any disconnected components. Clear PCM memory and repeat QUICK TEST . If a fault is not indicated, unable to duplicate or identify fault at this time. Go to CIRCUIT TEST Z, step 1).
  26. 33) DTC P1445: Check PFS High Voltage To PCM  Disconnect PFS harness connector. Check for loose pins or broken wires by pulling moderately on the PF and PWR GND circuits at PFS harness connector. Repair as necessary. Reconnect PFS harness connector. Connect scan tool to DLC. Turn ignition on, engine off. Access EVAPPF PID (PFS input to the PCM range is 0.40 to 4.80 volts). Turn ignition off. If EVAPPF PID voltage was greater than 4.80 volts, go to next step. If EVAPPF PID voltage was not greater than 4.80 volts, DTC P1445 fault is intermittent. Go to step 39).
  27. 34) Check VPWR Resistance For Short To PF Circuit In PFS  Turn ignition off. Disconnect PFS harness connector. Allow the vehicle and PFS to cool down or warm up to a room temperature, 55-80°F (13-27°C), before taking a resistance measurement on the PFS. This can take 15 to 20 minutes. Measure resistance between VPWR and PF pins on the PFS. See Fig 5. If resistance is 40-230 ohms, go to next step. If resistance is not 40-230 ohms, replace damaged PFS. Reconnect any disconnected components and go to step 42).
  28. 35) Check PFS Voltage Input To PCM  Turn ignition on, engine off. Measure PF circuit voltage between PFS harness connector and battery negative post. Turn ignition off. If the voltage was greater than 10.5 volts, go to next step. If the voltage was not greater than 10.5 volts, go to step 37).
  29. 36) Check PF Circuit For Short To VPWR  Install PCM breakout box to harness connector, leave PCM disconnected. Turn ignition on, engine off. Measure resistance between PCM test pin 11 and PCM test pins 24 or 103. If the voltage is greater than 10.5 volts, repair short circuit. Reconnect any disconnected components. Clear PCM memory and repeat QUICK TEST . If voltage is not greater than 10.5 volts, replace damaged PCM. Reconnect any disconnected components. Clear PCM memory and repeat QUICK TEST .
  30. 37) Check PF Circuit For Open  Install PCM breakout box to harness connector, leave PCM disconnected. Measure resistance of PF circuit between PCM test pin 11 and PFS harness connector. If the resistance is less than 5.0 ohms, go to next step. If the resistance is not less than 5.0 ohms, repair open circuit. Reconnect any disconnected components. Clear PCM memory and repeat QUICK TEST .
  31. 38) Check PWR GND Circuit For Open  Measure resistance of PWR GND circuit between PCM test pin 24 or 103 and PFS harness connector. If the resistance is less than 5.0 ohms, replace damaged PCM. Reconnect any disconnected components. Clear PCM memory and repeat QUICK TEST . If resistance is not less than 5.0 ohms, repair open circuit. Reconnect any disconnected components. Clear PCM memory and repeat QUICK TEST .
  32. 39) Check PFS Circuit For Intermittent PF Open Or VPWR Short  Turn ignition on, engine off. Using scan tool, access EVAPPF PID. Observe EVAPPF PID for an indication of a fault while performing the following: Lightly tap on PF sensor, wiggle PFS connector and harness between sensor and PCM. A fault is indicated by a sudden change in EVAPPF PID voltage (greater than 4.80 volts). If a fault is indicated, isolate fault and repair as necessary. Reconnect any disconnected components. Clear PCM memory and repeat QUICK TEST . If fault is not indicated, unable to duplicate or identify fault at this time. Go to CIRCUIT TEST Z, step 1.
  33. 40) DTC P0443: Check EVAP Canister Purge Valve Circuit For Intermittent  Rerun KOEO, KOER Self-Tests and retrieve Continuous Memory DTCs. If DTC P0443 is present in Continuous Memory Self-Test only, go to next step. If DTC P0443 is present in KOEO or KOER Self-Tests, go to step 1).
  34. 41) Check EVAP Canister Purge Valve Circuit For Intermittent Open Or Short  Install PCM breakout box to harness connector, leave PCM disconnected. Measure resistance between PCM test pin 67 and PCM test pin 71, while performing the following: Lightly tap on the EVAP canister purge valve and observe a resistance change. Wiggle the EVAP canister purge valve connector and vehicle harness between the valve and the PCM, observe a resistance change. If the resistance reading changes to below 30 ohms or above 90 ohms, isolate fault and repair as necessary. Reconnect any disconnected components. Clear PCM memory and repeat QUICK TEST . If the resistance reading does not changes to below 30 ohms or above 90 ohms, unable to duplicate or identify fault at this time. Go to CIRCUIT TEST Z, step 1.
  35. 42) Verification If EVAP System Repair  Plug or tape atmospheric vent cap on EVAP canister (if applicable). Remove fuel filler cap at fuel filler pipe. Install Rotunda Evaporative Emission System Leak Tester (134-00056) or equivalent including the nitrogen or argon gas supply and pressure regulator. Disconnect and plug fuel vapor hose to PFS from intake manifold at the intake manifold vacuum source. Pressurize the EVAP system at 27 in. H2O (6.74 kPa) with tester. Observe tester installation leak self-test for two minutes and then the EVAP system leak test. Listen for a vacuum leak noise and check for substantial fuel vapor odors at isolated areas in the EVAP system. If the pressure applied to the EVAP system holds, remove plug and reconnect fuel vapor hose from PFS at intake manifold vacuum source. Remove EVAP System Leak Tester. Reinstall fuel filler cap. Tighten cap only one eighth turn so that cap initially clicks by sound or touch. Clear PCM memory to clear DTCs. Using scan tool, access EVAPPDC PID. Drive vehicle (including a steady accelerator speed over 50 mph until EVAPPDC PID shows 75 percent duty cycle). Then maintain approximate speed until duty cycle reaches zero percent. After additional 2 minutes of driving, bring vehicle to an idle. Repeat QUICK TEST . Verify a symptom no longer exists. If the pressure applied to the EVAP system does not hold, go to step 43).
  36. 43) Check Location Of EVAP System Pressure Leak  Systematically isolate area of potential pressure leak. Close off pressure to EVAP system. Disconnect and plug fuel vapor hose from fuel tank at EVAP canister. Apply controlled pressure at 27 in. H2O (6.74 kPa) to the EVAP system with the leak tester. If pressure now holds, diagnosis canister and repair as necessary. If system pressure cannot hold, close pressure supply to system. Disconnect and plug fuel vapor hose from EVAP canister at EVAP canister purge valve. Again, apply controlled pressure to the EVAP system. If the pressure holds, remove the plugs. Reconnect fuel vapor hose at EVAP canister. Return to step 18) to check EVAP canister purge valve integrity. Remove EVAP System Leak Tester. Reinstall fuel filler cap. Clear PCM memory to clear DTCs. Using scan tool, access EVAPPDC PID. Drive vehicle (including a steady accelerator speed over 50 mph until EVAPPDC PID shows 75 percent duty cycle). Then maintain approximate speed until duty cycle reaches zero percent. After additional 2 minutes driving, bring vehicle to an idle. Repeat QUICK TEST . Verify a symptom no longer exists. If the pressure does not hold, remove the plugs. Check for fuel vapor hose cracks or fuel vapor valve damage. Examine and secure fuel vapor hose connections to components. Repair or replace as necessary. Remove EVAP System Leak Tester. Reinstall fuel filler cap. Clear PCM memory to clear DTCs. Using scan tool, access EVAPPDC PID. Drive vehicle (including a steady accelerator speed over 50 mph until EVAPPDC PID shows 75 percent duty cycle). Then maintain approximate speed until duty cycle reaches zero percent. After additional 2 minutes driving, bring vehicle to an idle. Repeat QUICK TEST . Verify a symptom no longer exists.
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