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Fuel Pump Control Circuit: Sienna

  1. If using scan tool, go to next step. If scan tool is not available, go to step  3.
  2. Check operation of fuel pump by using scan tool. See FUEL PUMP OPERATION under FUEL SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - V6 & V8 article. If fuel pump does not operate and fuel pressure does not exist in fuel inlet line at fuel filter, go to step  4. If fuel pump operates and fuel pressure exists in fuel inlet line at fuel filter, check starter signal circuit. See STARTER SIGNAL CIRCUIT .
  3. Remove passenger's side lower instrument panel cover for access to ECM. For illustration of ECM location, see THEORY & OPERATION article. Note ECM terminals. See Figure. Turn ignition on. Momentarily connect jumper wire between body ground and terminal No. 3 (Light Green/Red wire) at ECM electrical connector E8 to operate the fuel pump. This is the FC terminal at ECM. Ensure fuel pump operates and fuel pressure exists in fuel inlet line at fuel filter. If fuel pump does not operate and fuel pressure does not exist in fuel inlet line at fuel filter, go to next step. If fuel pump operates and fuel pressure exists in fuel inlet line at fuel filter, check starter signal circuit. See STARTER SIGNAL CIRCUIT .
  4. Check ECM power source circuit. See ENGINE CONTROL MODULE (ECM) POWER SOURCE CIRCUIT . If ECM power source circuit is okay, go to next step. If ECM power source circuit is defective, repair as necessary.
  5. Check operation of circuit opening relay. See CIRCUIT OPENING RELAY  under MOTORS & RELAYS. If circuit opening relay operates properly, go to next step. If circuit opening relay is defective, replace circuit opening relay.
  6. Remove passenger's side lower instrument panel cover for access to ECM if not previously done. For illustration of ECM location, see THEORY & OPERATION article. Note ECM terminals. See Figure.
  7. Turn ignition on. Using voltmeter, check voltage between body ground and terminal No. 3 (Light Green/Red wire) at ECM electrical connector E8. This is the FC terminal at ECM. Voltage should be 9-14 volts. If voltage is within specification, go to next step. If voltage is not within specification, check for open in wiring harness and connectors between ECM and circuit opening relay, and between ignition switch and circuit opening relay. See appropriate wiring diagram in WIRING DIAGRAMS article. It may be necessary to check IGN fuse. IGN fuse is located in fuse box behind driver's side of instrument panel. Repair wiring harness or electrical connectors as necessary.
  8. Check fuel pump resistance and operation. See FUEL DELIVERY  under FUEL SYSTEMS. If fuel pump resistance is within specification and fuel pump operates, go to next step. If fuel pump resistance is not within specification or fuel pump does not operate, replace fuel pump.
  9. Check for open in wiring harness and electrical connectors between circuit opening relay and fuel pump, and between fuel pump and body ground. See appropriate wiring diagram in WIRING DIAGRAMS article. If wiring harness and electrical connectors are okay, go to next step. If wiring harness or electrical connector are defective, repair as necessary.
  10. Check ECM ground circuit. See appropriate wiring diagram in WIRING DIAGRAMS article. If ECM ground circuit is defective, repair ground circuit as necessary. If ECM ground circuit is okay, replace ECM. If ECM is replaced, ECM must be programmed with proper ignition key code for engine immobilizer system. For programming procedures, see COMPUTER RELEARN PROCEDURES article in GENERAL INFORMATION.
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