Inspection Procedure 30
CIRCUIT OPERATION- A battery positive voltage is applied on the fuel pump relay (terminal 3, 4) from the ignition switch-IG.
- During cranking and while the engine is running, the PCM turns the power transistor in the PCM "ON" to ground the fuel pump relay coil. With this, the fuel pump relay turns "ON", and the battery positive voltage is supplied to the fuel pump from the fuel pump relay (terminal 1).
TROUBLESHOOTING HINTS
The most likely causes for this code to be set are:
- Malfunction of the fuel pump relay.
- Malfunction of the fuel pump.
- Improper connector contact, open or short-circuited harness wire.
- PCM failed.
WIRING DIAGRAM
CONNECTORS
DIAGNOSIS
Required Special Tool:
MB991502: Scan Tool (MUT-II)
CAUTION: To prevent damage to scan tool, turn the ignition switch "OFF" before connecting or disconnecting the scan tool.
STEP 1. Using scan tool MB991502, activate test item 07: Fuel Pump.
- An operating sound of the fuel pump should be heard.
If no sound is heard, go to Step 2.
If a sound is heard, this malfunction is intermittent. Refer to Troubleshooting/Inspection Service Points >.
STEP 2. Check the fuel pump operation.
1. Disconnect the fuel pump connector D-14.
2. Use jumper wires to connect the fuel pump connector terminal 5 to the positive battery terminal and terminal 4 to the negative battery terminal.
- An operating sound of the fuel pump should be heard.
If a sound is heard, go to Step 3.
If no sound is heard, replace the fuel pump. Then confirm that the malfunction is eliminated.
STEP 3. Check the ground line at the fuel pump connector D-14.
1. Disconnect the connector D-14 and measure at the harness side.
2. Check for the continuity between terminal 4 and ground.
- There should be continuity (0 Ohm). If continuity, go to Step 4.
If no continuity, repair the harness wire between the fuel pump connector D-14 and ground. Then confirm that the malfunction is eliminated.
STEP 4. Check the fuel pump relay.
1. Remove the fuel pump relay.
2. Check for the continuity between the fuel pump relay terminals 2 and 4.
- There should be continuity (approximately 70 Ohm).
3. Use jumper wires to connect the fuel pump connector terminal 4 to the positive battery terminal and terminal 2 to the negative battery terminal.
4. Check the continuity between fuel pump relay terminals 1 and 3 while connecting and disconnecting the jumper wire at the negative battery terminal.
- There should be continuity (0 Ohm) when the jumper wire is connected to the battery terminal, and there is no continuity when it is disconnected.
5. Install the fuel pump relay.
If all check 5 above meet the specifications, go to Step 5. If any checks above does not meet the specifications, replace the fuel pump relay. Then confirm that the malfunction is eliminated.
STEP 5. Check the power supply line at the fuel pump relay connector A-20X.
1. Disconnect the connector A-20X.
2. Turn the ignition switch "ON."
3. Connect the terminal 3 and ground, and terminal 4 and ground via a 20 Ohm resistor. Measure the current at this time.
- The current should be 0.5 ampere or more.
4. Turn the ignition switch "OFF."
If within specifications, go to Step 6.
If not within specifications, repair the harness wire between the fuel pump relay and the ignition switch. Then confirm that the malfunction is eliminated.
STEP 6. Check the circuit at the PCM connector C-39.
1. Disconnect the connector C-39 and measure at the harness side.
2. Turn the ignition switch "ON."
3. Connect the terminal 20 and ground via a 20-Ohm resistor. Measure the current at this time.
- The current should be 0.14 ampere or more.
4. Turn the ignition switch "OFF."
If within specifications, go to Step 7.
If not within specifications, repair the harness wire between the PCM connector C-39 and the fuel pump relay connector A-20X. Then confirm that the malfunction is eliminated.
STEP 7. Check the harness wire between the fuel pump connector D-14 and the PCM connector C-39.
NOTE: Check the wire after checking the intermediate connectors C-17, C-69. If the intermediate connectors C-17, C-69 is damaged, repair or replace it. Refer to Harness Connector Inspection >. Then check that the malfunction is eliminated.
If the wire between the fuel pump connector D-14 and the PCM connector C-39 is not damaged, go to Step 8.
If the wire between the fuel pump connector D-14 and the PCM connector C-39 is damaged, repair it. Then confirm that the malfunction is eliminated.
STEP 8. Check the harness connector C-39 at the PCM for damage.
If the harness connector C-39 is damaged, repair or replace it. Refer to Harness Connector Inspection >.
If harness connector C-39 is in good condition, replace the PCM.
Then check the malfunction is eliminated.