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Diagnosis & Repair

WARNING: This page is about a different car, the 2002 Toyota Sienna. However, it is still accessible from the selected car via links, so may be relevant.
  1. Start engine and warm to engine to normal operating temperature. Ensure A/C and all accessories are off. Apply parking brake. Place transaxle in Neutral. Connect Toyota hand-held tester or scan tool to Data Link Connector (DLC) No. 3 at driver's side of instrument panel. See Figure.
  2. Note location of data link connector No. 1 on engine mount bracket at passenger's side front of engine. See Fig 1. Install Jumper Wire (SST 09843-18020) between terminals TC and E1 on data link connector No. 1. See Fig 1. Note engine speed in less than 5 seconds and at more than 5 seconds after installing jumper wire. If difference in engine speed is 100 RPM or less, shut engine off and remove jumper wire. Go to next step. If difference in engine speed is more than 100 RPM, shut engine off. Remove jumper wire and go to step  8.
    Fig 1: Locating Data Link Connector No. 1 & Identifying Terminals TC & E1 On Data Link Connector No. 1
    G00023128Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  3. Check for any loose or defective connections at PCV valve and hose. PCV valve is located on firewall side valve cover at timing belt end of engine. If PCV valve and hose connections are okay, go to next step. If PCV valve or hose connections are defective, repair or replace components as necessary.
  4. Ensure ignition is off. Remove glove box for access to ECM with electrical connectors still installed on ECM. See Figure. Disconnect ECM electrical connector E12. See Figure.
  5. Turn ignition on. Using voltmeter, check voltage between body ground and terminal No. 26 (Red/White wire) at ECM electrical connector E12. See Figure. This is the RSO terminal on ECM. Voltage should be 9-14 volts. If voltage is within specification, go to next step. If voltage is not within specification, check IAC valve operation. See IDLE AIR CONTROL VALVE under IDLE CONTROL SYSTEMS in SYSTEM & COMPONENT TESTING - V6 & V8 article. If IAC valve is defective, replace IAC valve. If IAC valve is okay, check for open and short in wiring harness and electrical connectors between EFI main relay and IAC valve, and between IAC valve and ECM. See WIRING DIAGRAMS article. EFI main relay may also be referred to as EFI relay. EFI main relay is located in fuse/relay box at driver's side front corner of engine compartment. See WIRING DIAGRAMS article. Repair wiring as necessary.
  6. Check IAC valve operation. See IDLE AIR CONTROL VALVE under IDLE CONTROL SYSTEMS in SYSTEM & COMPONENT TESTING - V6 & V8 article. If IAC valve is okay, go to next step. If IAC valve is defective, replace IAC valve.
  7. Remove IAC valve from throttle body. Inspect IAC valve and passages for carbon build-up and blockage. If a problem exists, repair as necessary. If problem does not exist, replace ECM.
  8. Ensure engine oil dipstick, oil filler cap, PCV system and all other air induction system components are intact and operating properly. If problem exists, repair as necessary. If problem does not exist, an open or short in A/C signal circuit to ECM may exist. Repair as necessary. On manual A/C models, it may be necessary to check the A/C amplifier. See appropriate MANUAL A/C-HEATER SYSTEMS article in AIR CONDITIONING & HEATING.
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