HX21 - HX30

HX21 - Check For Blockage Between The Evaporative Test Port And Fuel Tank

- 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.
- REMOVE fuel filler cap.

Does the pressure drop rapidly (quickly)?

YES GO to Powertrain Management for
NO REMOVE the EVAP System Leak Tester from diagnostic symptom condition listed as Hiss When Opening Fuel Cap. REPEAT Pinpoint Test Step HX21 to VERIFY a blockage no longer exists. Then, GO to HX22. the fuel filler pipe. GO to HX22.

HX22 - Check Fuel Tank Pressure Sensor PIDs With Fuel Filler Cap Removed

Note: FTP sensor voltage reading with key in ON position and with fuel filler cap removed is 2.40 to 2.80 volts.

- Remove fuel filler cap.
- Key on, engine off.
- Access the FTP (FTP V] PIDs on the scan tool.
- Record the reading.

Is FTP [FTP V] PID reading between -0.37 and 0.37 kPa (-1.50 and 1.50 in-H 20) [2.40 and 2.80 volts] with the fuel filler cap oft?

YES INSTALL the fuel filler cap only one eighth turn so that the cap initially clicks by sound or touch. GO to HX23.
NO GO to HX24.

HX23 - Check For Stuck Open EVAP Canister Purge Valve Condition At Idle

NOTE: When the EVAPPDC PID reads zero the FTP [FTP V] PID must read above -0.37 kPa (-1.50 in-H 20) [2.40 volts].

- Open the CV solenoid to atmosphere by removing the plug from the canister vent hose assembly or the tape from the the CV solenoid filter cap.
- Remove plug and reconnect the EVAP return tube (EVAP canister purge valve to intake manifold) at the intake manifold vacuum source.
- Verify fuel filler cap is installed.
- Key on, engine off.
- Access the FTP, FTP V and EVAPPDC PIDs on the scan tool.
- Start engine.

When EVAPPDC PID is zero, is the FTP [FTP V] PID reading below -0.37 kPa (-1.50 in-H 20) 2.40 volts]?

YES The EVAP canister purge valve stuck open. REPLACE EVAP canister purge valve. INSTALL the EVAP System Leak Tester or equivalent to the evaporative test port. PERFORM the EVAP system leak test to VERIFY a leak did not occur on the EVAP canister purge valve installation. Then, REPEAT Pinpoint Test Step HX23 to VERIFY repair. PERFORM the Vehicle Preparation for Monitor Repair Verification Drive Cycle and RERUN Evaporative Emission Running Loss Monitor Repair Verification Drive Cycle.
NO If the FTP (FTP V) PID readings are within the range specified in Pinpoint Test Step HX22, PERFORM the EVAP system leak test to VERIFY no leak exists. PERFORM the Vehicle Preparation for Monitor Repair Verification Drive Cycle and RERUN Evaporative Emission Running Loss Monitor Repair Verification Drive Cycle. Otherwise, GO to HX19 to find additional blockages.

HX24 - Check Voltage Between VREF And SIG RTN Circuits At FTP Sensor

- Disconnect FTP sensor.
- Key on, engine off.
- Measure voltage between VREF and SIG RTN circuits at the FTP sensor harness connector.
- Key off.

Was voltage between 4.0 and 6.0 volts?

YES REPLACE damaged FTP sensor. After replacing FTP sensor, PERFORM an EVAP System leak test at the evaporative test port to VERIFY repair caused no leak. Then, GO to HX22 to VERIFY the repair.
NO GO to HX25.

HX25 - Check For Open VREF Circuit Between PCM And FTP Sensor

- Install breakout box, leave PCM disconnected.
- Measure resistance of VREF circuit between PCM test pin 90 and FTP sensor harness connector.

Is resistance less than 5.0 ohms?

YES REPLACE PCM. RESTORE vehicle. Then, GO to HX22 to VERIFY the repair.
NO REPAIR open circuit. RESTORE vehicle. Then, GO to HX22 to VERIFY the repair.

HX26 - DTC P0452: Check For FTP Sensor Connector Contamination

Diagnostic Trouble Code (DTC) P0452 indicates that Self-Test has detected an FTP circuit input below minimum. Possible causes:
- Fuel tank pressure (FTP) sensor completely submerged in liquid fuel.
- Inside contamination of the electrical connector on the FTP sensor.
- FTP short to SIG RTN or PWR GND.
- Damaged FTP sensor.
- Damaged PCM.

- Key off.
- Visually check for contamination of the FTP sensor electrical connector.
- Check for completely submerged FTP sensor in liquid fuel (can affect correct FTP voltage reading).

Does FTP sensor and its electrical connector show signs of contamination?

YES REPAIR FTP sensor electrical connector as necessary. COMPLETE PCM Reset to clear DTCs. RERUN Quick Test.
NO GO to HX27.

HX27 - Check For Low FTP Sensor Voltage

- Key off.
- Connect scan tool.
- Key on, engine off.

NOTE: FTP sensor input with no pressure/vacuum on the fuel tank (filler cap open or not open to atmosphere) is between 2.37 and 2.97 volts.

- Access FTPVPID.

Is FTP V PID voltage less than 0.22 volt?

YES GO to HX28.
NO The fault that produced the DTC P0452 is intermittent. GO to HX31.

HX28 - Check Opposite Induced High FTP Signal

- Key off.
- Disconnect FTP sensor.
- Connect a jumper wire between VREF circuit and FTP circuits at the FTP sensor harness connector.
- Key on, engine off.
- If a scan tool communication concern exists, remove jumper immediately and go directly to HX29 .
- Access FTPVPID.

Is FTP V PID value between 4.0 and 6.0 volts?

YES REPLACE damaged FTP sensor. RESTORE vehicle. RERUN EVAP System Leak Test at evaporative test port to VERIFY the repair. PERFORM the Vehicle Preparation for Monitor Repair Verification Drive Cycle and RERUN Evaporative Emission Running Loss Monitor Repair Verification Drive Cycle.
NO REMOVE jumper. GO to H29.

HX29 - Check Voltage Between VREF And SIG RTN Circuits At FTP Sensor

- Key on, engine off.
- Measure voltage between VREF and SIG RTN circuits at the FTP sensor harness connector.
- Key off.

Was VREF voltage between 4.0 and 6.0 volts?

YES Go to HX3O.
NO VREF voltage is out of range. GO to Pinpoint Test Step C1.

HX30 - Check FTP Circuit For Short To SIG RTN Or PWR GND In Harness

- Install breakout box, leave PCM disconnected.
- Disconnect scan tool from DLC.
- Measure resistance between PCM test pins 62 and 91.
- Measure resistance between PCM test pin 62 and PCM test pins 51 and 103.

Are both resistances greater than 10,000 ohms?

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