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Tundra 3.4L V6

  1. Remove glove box for access to ECM. For illustration of ECM location, see THEORY & OPERATION article. Note ECM electrical connector terminal identification. See Figure.
  2. Turn ignition on. Using voltmeter, check voltage between terminals No. 16 (White/Blue wire) at ECM electrical connector E3 and No. 17 (Brown wire) at ECM electrical connector E6. This is the +B and E1 terminals at ECM. Voltage should be 9-14 volts. If voltage is within specification, diagnose by symptom. See TROUBLE SHOOTING - NO CODES article. If voltage is not within specification, check for open in wiring harness and electrical connectors between terminal No. 17 (Brown wire) at ECM electrical connector E6 and body ground. See 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.
  3. Ensure ignition is on. Using voltmeter, check voltage between body ground and terminal No. 2 (Black/Orange wire) at ECM electrical connector E3. This is the IGSW terminal at ECM. Voltage should be 9-14 volts. If voltage is not within specification, go to next step. If voltage is within specification, go to step  7.
  4. Check for defective IGN fuse. IGN fuse is located in fuse box behind driver's side of instrument panel. If IGN fuse is okay, go to next step. If IGN fuse is defective, repair short in wiring harness and components connected to IGN fuse. See WIRING DIAGRAMS article.
  5. Check ignition switch. See appropriate STEERING COLUMN SWITCHES article in ACCESSORIES & EQUIPMENT. If ignition switch is okay, go to next step. If ignition switch is defective, replace ignition switch.
  6. Check wiring harness and electrical connectors between battery and ignition switch, and between ignition switch and terminal No. 2 (Black/Orange wire) at ECM electrical connector E3. See WIRING DIAGRAMS article. If necessary to check AM2 fuse, AM2 fuse is located in fuse/relay box at driver's side front corner of engine compartment, near battery. Repair wiring harness or electrical connectors as necessary.
  7. Ensure ignition is on. Using voltmeter, check voltage between body ground and terminal No. 8 (Black/Yellow wire) at ECM electrical connector E3. This is the MREL 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 ECM ground circuit. See WIRING DIAGRAMS article. If ECM ground circuit is defective, repair ground circuit as necessary. If ECM ground circuit is okay, replace ECM.
  8. Check for defective EFI No. 1 fuse. EFI No. 1 fuse is located in fuse/relay box at driver's side front corner of engine compartment, near battery. If EFI No. 1 fuse is okay, go to next step. If EFI No. 1 fuse is defective, repair short in wiring harness and components connected to EFI No. 1 fuse. See WIRING DIAGRAMS article.
  9. Check operation of EFI main relay. See EFI MAIN RELAY  under MODULES, MOTORS, RELAYS & SOLENOIDS. If EFI main relay operates properly, go to next step. If EFI main relay is defective, replace EFI main relay.
  10. Check for open and short in wiring harness and electrical connectors between terminal No. 8 (Black/Yellow wire) at ECM electrical connector E3 and EFI main relay, and for open in White/Black wire between EFI main relay and body ground. See 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.
  11. Check wiring harness and electrical connectors between battery and EFI No. 1 fuse, and between EFI No. 1 fuse and EFI main relay. See WIRING DIAGRAMS article. Repair wiring harness or electrical connectors as necessary.
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