HX11 - HX20

HX11 - DTC P0443: Check VPWR Voltage To EVAP Canister Purge Valve

Diagnostic Trouble Code (DTC) P0443 indicates a failure in the EVAP canister purge valve circuit. Possible causes:
- VPWR circuit open.
- EVAP canister purge valve circuit open.
- EVAP canister purge valve circuit shorted to PWR GND.
- EVAP canister purge valve circuit shorted to VPWR.
- Damaged EVAP canister purge valve.
- Damaged PCM.

- Key off.
- Disconnect EVAP canister purge valve.
- Key on,engine off.
- Measure voltage between VPWR circuit at the EVAP canister purge valve harness connector and battery negative post.
- Key off.

Was voltage greater than 10.5 volts?

YES GO to HX12.
NO REPAIR open circuit. RESTORE vehicle. COMPLETE PCM Reset to clear DTCs. RERUN Quick Test.

HX12 - Check EVAP Canister Purge Valve Resistance

NOTE: EVAP canister purge valve resistance reading must be taken with engine cooled down.

- Disconnect EVAP canister purge valve.
- Measure EVAP canister purge valve (EVAP canister purge valve) resistance.

Is resistance between 30 and 38 ohms?

YES GO to HX13.
NO REPLACE damaged EVAP canister purge valve. COMPLETE PCM Reset to clear DTCs. RERUN EVAP System Leak Test at evaporative test port to VERIFY the repair. RERUN Evaporative Emission Running Loss Monitor Repair Verification Drive Cycle.

HX13 - Check EVAP Canister Purge Valve Circuit For Open In Harness

- Install breakout box leave PCM disconnected.
- Measure resistance of EVAP canister purge valve circuit between PCM test pin 56 and EVAP canister purge valve harness connector.

Is resistance less than 5.0 ohms?

YES GO to HX14.
NO REPAIR open circuit. RESTORE vehicle. COMPLETE PCM Reset to clear DTCs. RERUN Quick Test.

HX14 - Check EVAP Canister Purge Valve Circuit For Short To PWR GND In Harness

- Disconnect scan tool from DLC.
- Measure resistance between PCM test pin 56 and PCM test pins 24 and 103.

Are both resistances greater than 10,000 ohms?

YES GO to HX15.
NO REPAIR short circuit. RESTORE vehicle. COMPLETE PCM Reset to clear DTCs. RERUN Quick Test.

HX15 - Check EVAP Canister Purge Valve Circuit For Short To VPWR In Harness

- Key on, engine off.
- Measure voltage between PCM test pin 56 and PCM test pins 51 and 103.
- Key off.

Was voltage greater than 10.5 volts?

YES REPAIR short circuit. RESTORE vehicle. COMPLETE PCM Reset to clear DTCs. RERUN RERUN Quick Test.
NO REPLACE damaged PCM. RESTORE vehicle. Quick Test.

HX16 - Check EVAP Canister Purge Valve Circuit For Intermittent Open

- Key off.
- Install breakout box, leave PCM disconnected.
- Measure the resistance between PCM test pins 56 and 71 while performing the following:
- Lightly tap on EVAP canister purge valve and observe a resistance change.
- Wiggle EVAP canister purge valve connector and harness between valve and PCM, observe a resistance change.

Does the resistance reading change to below 30 ohms or above 38 ohms?

YES ISOLATE fault and REPAIR as necessary. RESTORE vehicle. COMPLETE PCM Reset to clear DTCs. RERUN EVAP System Leak Test at evaporative test port to VERIFY the repair. RERUN Evaporative Emission Running Loss Monitor Repair Verification Drive Cycle.
NO UNABLE to duplicate or identify fault at this time. GO to Pinpoint Test Step Z1 with the following data: resistance readings from this test and a list of Possible causes.

HX18 - DTC P0446 OR P1450: Check For Visual Causes Of Excessive Fuel Tank Vacuum

Continuous Memory Diagnostic Trouble Code (DTC) P0446 or P1450 indicates that Self-Test has detected the Evaporative Emission Control System has excessive fuel tank vacuum. Also, a DTC P0446 indicates a vent control malfunction. Possible causes:
- EVAP canister purge outlet tube (EVAP canister purge valve to EVAP canister) blockages or kinks.
- EVAP canister tube (fuel tank to EVAP canister) blockages or kinks.
- Fuel vapor elbow on EVAP canister contaminated.
- Restricted EVAP canister.
- Canister vent (CV) solenoid stuck closed (partially or fully).
- Plugged or contaminated CV solenoid filter.
- EVAP canister purge valve stuck open.
- Fuel filler cap stuck closed (no vacuum relief).
- VREF circuit open in fuel tank pressure (FTP) sensor.
- Damaged FTP sensor.

NOTE: Remove the EVAP canister-CV solenoid and fuel tank assemblies if they are not accessible to perform the following step.

- Check for kinks or bends in the fuel vapor hoses/tubes (EVAP canister purge outlet tube and EVAP canister tube).
- Visually inspect EVAP canister inlet port, CV solenoid filter and canister vent hose assembly for contamination or debris.
- Check CV solenoid filter for blockage or contamination.

Is a fault indicated?

YES REMOVE any contamination or debris around fuel vapor hoses/tubes and EVAP canister-CV solenoid assembly. REMOVE kinks or bends in EVAP canister purge outlet tube, EVAP canister tube and canister vent hose assembly. GO to HX19.
NO GO to HX19.

HX19 - Check For Blockage Between The Evaporative Test Port And EVAP Canister-CV Solenoid Assembly

- Disconnect and plug the EVAP return tube (EVAP canister purge valve to intake manifold) at the intake manifold vacuum source.
- Plug (tape) the CV solenoid (or filter) or plug the canister vent hose assembly.
- Locate evaporative test port [marked EVAPORATIVE SERVICE PORT DO NOT USE UNREGULATED PRESSURE ABOVE 6.89 kPa (1 PSI)1 near EVAP canister purge valve or EVAP canister.
- Install Rotunda Evaporative Emission System Leak Tester 310-F007 (134-00056) or equivalent at the test port.
- Regulate the nitrogen or argon gas pressure on the tester to 3.48 kPa (14 in-H 2 0).
- Pressurize the EVAP system to 3.48 kPa (14 in-H 20).
- Remove the plug (tape) from the CV solenoid or the plug from the canister vent hose assembly.

Does the EVAP system pressure drop rapidly (quickly)?

YES REMOVE EVAP System Leak Tester from test port. REINSTALL evaporative evaporative test port cap. GO to HX2O.
NO REPEAT Pinpoint Test Step HX19 to VERIFY blockage no longer exists. GO to HX22.

HX20 - Pressure Check The Fuel Filler Cap

NOTE: When performing a check for leaks or blockages in the EVAP system, energize (close) the canister vent (CV) solenoid through the scan tool for a maximum of nine minutes per pinpoint test step. Then de-energize the CV solenoid prior to performing the subsequent pinpoint test step. This is done to assure proper closing of the solenoid.

- Install the EVAP System Leak Tester at the fuel filler pipe.
- Follow the instructions that come with the EVAP System Leak Tester kit to perform TESTING AT FILLER NECK.
- Key on, engine off.
- Close CV solenoid by accessing Output Test Mode on the scan tool.
- Pressurize the EVAP system to 3.48 kPa (14 in-H 20) at the evaporative test port.

NOTE: The Rotunda Engine EAR Amplifier (1 07-R21 00) is an optional tool to be used if noise level hinders the effectiveness of the ultra-sonic detector. Access the ultra-sonic detector from the EVAP System Leak Tester kit.

- Slowly pass the detector probe around the fuel filler cap and the evaporative test port.

Is an audible change around the fuel filler cap indicated?

YES REPLACE fuel filler cap. REPEAT HX2O to VERIFY repair. GO to HX21.
NO GO to HX21.