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Engine Control Module Power Source Circuit: Camry

  1. Remove glove box for access to Engine Control Module (ECM). For illustration of ECM location, see THEORY & OPERATION article. Note ECM electrical connector terminals. See Figure.
  2. Turn ignition on. Using voltmeter, check voltage between terminals No. 1 (Black/Red wire) at ECM electrical connector E6 and No. 1 (Brown wire) at ECM electrical connector E8. This is the +B and E1 terminals at ECM. Voltage should be 9-14 volts. If voltage is not within specification, go to next step. If voltage is within specification, diagnose by symptom. See TROUBLE SHOOTING - NO CODES article.
  3. Turn ignition off. Disconnect electrical connector E8 from ECM. Using ohmmeter, check for continuity between body ground and terminal No. 1 (Brown wire) at ECM electrical connector E8. If continuity exists, reinstall electrical connector E8 at ECM and go to next step. If continuity does not exist, repair open in Brown wire between terminal No. 1 at ECM electrical connector E8 and body ground. See WIRING DIAGRAMS article.
  4. Ensure ignition is off. Check for open and short in Black/Red wire between EFI main relay and terminal No. 1 at ECM electrical connector E6. See WIRING DIAGRAMS article. EFI main relay is located in fuse/relay box at driver's side front corner of engine compartment. If wiring is okay, go to next step. If wiring is defective, repair as necessary.
  5. Turn ignition on. Using voltmeter, check voltage between terminals No. 9 (Black/Orange wire) at ECM electrical connector E6 and No. 1 (Brown wire) at ECM electrical connector E8. This is the IGSW and E1 terminals 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  9.
  6. Check for defective IG2 fuse. IG2 fuse is located in fuse/relay box at driver's side front corner of engine compartment. If IG2 fuse is okay, go to next step. If IG2 fuse is defective, repair short in wiring harness and components connected to IG2 fuse. See WIRING DIAGRAMS article.
  7. Check for defective AM2 fuse. AM2 fuse is located in fuse/relay box at driver's side front corner of engine compartment. If AM2 fuse is okay, go to next step. If AM2 fuse is defective, repair short in wiring harness and components connected to AM2 fuse. See WIRING DIAGRAMS article.
  8. Check ignition switch. See IGNITION SWITCH  under ENGINE SENSORS & SWITCHES. If ignition switch is okay, repair wiring harness or electrical connectors between ignition switch and terminal No. 9 (Black/Orange wire) at ECM electrical connector E6. See WIRING DIAGRAMS article. If ignition switch is defective, replace ignition switch. See IGNITION SWITCH under ENGINE SENSORS & SWITCHES in REMOVAL, OVERHAUL & INSTALLATION - 4-CYLINDER article.
  9. Ensure ignition is on. Using voltmeter, check voltage between terminals No. 8 (Black/White wire) at ECM electrical connector E6 and No. 1 (Brown wire) at ECM electrical connector E8. This is the MREL and E1 terminals 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. 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, or appropriate ENGINE IMMOBILIZER SYSTEMS article in ACCESSORIES & EQUIPMENT.
  10. Check for defective EFI fuse. EFI fuse is located in fuse/relay box at driver's side front corner of engine compartment. 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 WIRING DIAGRAMS article.
  11. 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.
  12. Check for open and short in wiring harness and electrical connectors between terminal No. 8 (Black/White wire) at ECM electrical connector E6 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 is defective, repair as necessary.
  13. Check wiring harness and electrical connectors between battery and EFI fuse. See WIRING DIAGRAMS article. Repair wiring harness or and electrical connectors as necessary.
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