DIAGNOSIS Required Special Tools: MB991958: Scan tool (MUT-III sub assembly) MB991824: V.C.I. MB991827: MUT-III USB cable MB991911: MUT-III main harness B • MB991658: Test harness set

STEP 1. Using scan tool MB991958, check data list item 73: Fuel Tank Differential Pressure Sensor.

To prevent damage to scan tool MB991958, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991958. (1) Connect scan tool MB991958 to the data link connector.

(2) Disconnect hose E from the evaporative emission canister side, and plug the hose. (3) Turn the ignition switch to the "ON" position. (4) Remove the fuel cap. (5) Set scan tool MB991958 to the data reading mode. • Item 73, Fuel Tank Differential Pressure Sensor. The fuel tank pressures reading on the scan tool should be -3.3 to 3.3 kPa (-0.97 to 0.97 inHg).

(6) Connect an evaporative emission system pressure pump to the fuel filler neck and pressurize the fuel tank. • The fuel tank pressure reading should increase. (7) Turn the ignition switch to the "LOCK" (OFF) position. Then disconnect scan tool MB991958. (8) Disconnect the evaporative emission system pressure pump, and reinstall the fuel cap. (9) Connect hose E to the canister. Q: Is the fuel tank pressure between -3.3 and 3.3 kPa (-0.97 and 0.97 inHg)? YES: It can be assumed that this malfunction is intermittent. (Refer to GROUP 00, How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunction ). Then go to Step 16 . NO: Go to Step 2 .

STEP 2. Measure the sensor output voltage at fuel tank differential pressure sensor connector E- 28.

(1) Disconnect hose E from the evaporative emission canister side, and plug the hose. (2) Remove the fuel tank mounting nuts, tilt the fuel tank.

(3) Disconnect fuel tank differential pressure sensor connector E-28.

(4) Connect special tool MB991658 between pressure sensor connector terminal 1, 2 and 3. (5) Turn the ignition switch to the "ON" position. (6) Remove the fuel cap. (7) Measure the voltage between terminal 1 and ground. The measured voltage should measure between 2.0 and 3.0 volts. (8) Turn the ignition switch to the "LOCK" (OFF) position. (9) Disconnect the evaporative emission system pressure pump, and reinstall the fuel cap. (10) Connect hose E to the canister. Q: Is the measured voltage between 2.0 and 3.0 volts? YES: Go to Step 7 . NO: Go to Step 3 .

STEP 3. Measure the 5-volt supply circuit voltage at fuel tank differential pressure sensor connector E-28.

(1) Disconnect fuel tank differential pressure sensor connector E-28.

(2) Connect special tool MB991658 between pressure sensor connector terminal 1, 2 and 3. (3) Turn the ignition switch to the "ON" position. (4) Measure the voltage between terminal 3 and ground. Voltage should measure between 4.7 and 5.1 volts. (5) Turn the ignition switch to the "LOCK" (OFF) position. Q: Is the measured voltage between 4.7 and 5.1 volts? YES: Go to Step 4 . NO: Go to Step 10 .

STEP 4. Check the ground circuit voltage at fuel tank differential pressure sensor connector E-28.

(1) Disconnect fuel tank differential pressure sensor connector E-28.

(2) Use special tool MB991658 to connect terminal 3 of the disconnected sensor connector and those of the harness side connector respectively. (3) Turn the ignition switch to the "ON" position. (4) Measure the voltage at the fuel tank differential pressure sensor side connector between terminal 2 and ground. Voltage should measure 0.5 volt or less. (5) Turn the ignition switch to the "LOCK" (OFF) position. Q: Is the measured voltage 0.5 volt or less? YES: Go to Step 5 . NO: Go to Step 12 .

STEP 5. Check connectors E-44, C-16, C-71 at intermediate connector and C-90 at PCM and E-28 at fuel tank differential pressure sensor for loose, corroded or damaged terminals, or terminals pushed back in the connector.

Q: Are the connectors and terminals in good condition? YES: Go to Step 6 . NO: Repair or replace the damaged components. (Refer to GROUP 00E, Harness Connector Inspection ). Then go to Step 16 .

STEP 6. Check the harness wire for open circuit between PCM connector C-90 terminal 57 and fuel tank differential pressure sensor connector E-28 terminal 2 for damage.

Q: Are the harness wires in good condition? YES: It can be assumed that this malfunction is intermittent. (Refer to GROUP 00, How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunction ). Then go to Step 16 . NO: Repair the damaged harness wires. Then go to 16 .

STEP 7. Measure the output circuit voltage at PCM connector C-91 by backprobing.

(1) Do not disconnect PCM connector C-91.

(2) Disconnect hose E from the evaporative emission canister side, and plug the hose. (3) Turn the ignition switch to the "ON" position.

(4) Measure the voltage between terminal 92 and ground by backprobing. The measured voltage should measure between 2.0 and 3.0 volts. (5) Turn the ignition switch to the "LOCK" (OFF) position. (6) Disconnect the evaporative emission system pressure pump, and reinstall the fuel cap. (7) Connect hose E to the canister. Q: Is the measured voltage between 2.0 and 3.0 volts? YES: Go to Step 8 . NO: Go to Step 9 .

STEP 8. Check connectors C-91 at PCM and E-28 at fuel tank differential pressure sensor for loose, corroded or damaged terminals, or terminals pushed back in the connector.

Q: Are the connector and terminals in good condition? YES: Go to Step 15 . NO: Repair or replace the damaged component. (Refer to GROUP 00E, Harness Connector Inspection ). Then go to Step 16 .

STEP 9. Check connectors E-44, C-16, at intermediate connector and C-91 at PCM and E-28 at fuel tank differential pressure sensor for loose, corroded or damaged terminals, or terminals pushed back in the connector.

Q: Are the connectors and terminals in good condition? YES: It can be assumed that this malfunction is intermittent. (Refer to GROUP 00, How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunction ). Then go to Step 16 . NO: Repair or replace the damaged components. (Refer to GROUP 00E, Harness Connector Inspection ). Then go to Step 16 .

STEP 10. Measure the 5-volt reference signal at PCM connector C-40 by backprobing.

(1) Do not disconnect PCM connector C-90. (2) Turn the ignition switch to the "ON" position.

(3) Measure the voltage between PCM connector C-90 terminal 46 and ground by backprobing. The measured voltage should measure between 4.8 and 5.2 volts. (4) Turn the ignition switch to the "LOCK" (OFF) position. Q: Is the measured voltage between 4.8 and 5.2 volts? YES: Go to Step 11 . NO: Go to Step 15 .

STEP 11. Check connectors E-44, C-16, at intermediate connector and C-90 at PCM and E-28 at fuel tank differential pressure sensor for loose, corroded or damaged terminals, or terminals pushed back in the connector.

Q: Are the connectors in good condition? YES: It can be assumed that this malfunction is intermittent. (Refer to GROUP 00, How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunction ). Then go to Step 16 . NO: Repair or replace the damaged component. (Refer to GROUP 00E, Harness Connector Inspection ). Then go to Step 16 .

STEP 12. Measure the fuel tank differential pressure sensor ground voltage at PCM connector C-90 by backprobing.

(1) Do not disconnect PCM connector C-90. (2) Turn the ignition switch to the "ON" position.

(3) Measure the voltage between terminal 57 and ground by backprobing. The measured voltage should measure 0.5 volt or less. (4) Turn the ignition switch to the "LOCK" (OFF) position. Q: Is the measured voltage 0.5 volt or less? YES: Go to Step 13 . NO: Go to Step 14 .

STEP 13. Check connectors E-44, C-16, C-71 at intermediate connector and C-90 at PCM and E-28 at fuel tank differential pressure sensor for loose, corroded or damaged terminals, or terminals pushed back in the connector.

Q: Are the connectors and terminals in good condition? YES: It can be assumed that this malfunction is intermittent. (Refer to GROUP 00, How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunction ). Then go to Step 16 . NO: Repair or replace the damaged components. (Refer to GROUP 00E, Harness Connector Inspection ). Then go to Step 16 .

STEP 14. Check connector C-90 at PCM for loose, corroded or damaged terminals, for terminals pushed back in the connector.

Q: Are the connectors and terminals in good condition? YES: Go to Step 15 . NO: Repair or replace the damaged components. (Refer to GROUP 00E, Harness Connector Inspection ). Then go to Step 16 .

STEP 15. Using scan tool MB991958, check data list item 73: Fuel Tank Differential Pressure Sensor.

To prevent damage to scan tool MB991958, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991958. (1) Connect scan tool MB991958 to the data link connector.

(2) Disconnect hose E from the evaporative emission canister side, and plug the hose. (3) Turn the ignition switch to the "ON" position. (4) Remove the fuel cap. (5) Set scan tool MB991958 to the data reading mode. • Item 73, Fuel Tank Differential Pressure Sensor. The fuel tank pressures reading on the scan tool should be -3.3 to 3.3 kPa (-0.97 to 0.97 inHg).

(6) Connect an evaporative emission system pressure pump to the fuel filler neck and pressurize the fuel tank. • The fuel tank pressure reading should increase. (7) Turn the ignition switch to the "LOCK" (OFF) position. Then disconnect scan tool MB991958. (8) Disconnect the evaporative emission system pressure pump, and reinstall the fuel cap. (9) Connect hose E to the canister. Q: Is the fuel tank pressure between -3.3 and 3.3 kPa (-0.97 and 0.97 inHg)? YES: It can be assumed that this malfunction is intermittent. (Refer to GROUP 00, How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunction ). Then go to Step 16 . NO: Replace the PCM. Then go to Step 16 .