2000 Toyota Avalon XLSFACTORY OEM SERVICE PROCEDURE

Engine Control Module (ECM) Power Source Circuit: 4Runner

  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 E14 and No. 17 (Brown wire) at ECM electrical connector E10. 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 E10 and body ground. 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/Blue wire) at ECM electrical connector E14. 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 appropriate wiring diagram in 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 ECM. See appropriate wiring diagram in WIRING DIAGRAMS article. Repair wiring harness or electrical connectors as necessary.
  7. Ensure ignition is on. Using voltmeter, check voltage between body ground and terminal No. 8 (Gray/Black wire) at ECM electrical connector E14. 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 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. On models equipped with engine immobilizer system, 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.
  8. Check for defective EFI fuse. EFI fuse is located in fuse/relay box at driver's side front corner of engine compartment, near battery. If EFI fuse is okay, go to next step. If EFI fuse is defective, repair short in wiring harness and components connected to EFI fuse. See appropriate wiring diagram in WIRING DIAGRAMS article.
  9. Check operation of EFI main relay. See EFI MAIN RELAY  under MOTORS & RELAYS. If EFI main relay operates properly, go to next step. If EFI main relay is defective, replace EFI main relay.
  10. Check for open or short in wiring harness and electrical connectors between terminal No. 8 (Gray/Black wire) at ECM electrical connector E14 and EFI main relay, and for open in White/Black wire between EFI main relay 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.
  11. Check wiring harness and electrical connectors between battery and EFI fuse. See appropriate wiring diagram in WIRING DIAGRAMS article. Repair wiring harness or electrical connectors as necessary.
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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.

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