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Tacoma Without ETCS

  1. Start engine. Warm engine to normal operating temperature. Ensure idle speed is within specification. See IDLE SPEED & MIXTURE in ON-VEHICLE ADJUSTMENTS - V6 & V8 article.
  2. Turn ignition off. Apply parking brake and place transmission/transaxle in Neutral. Ensure A/C is off.
  3. Note location of data link connector No. 3 at driver's side of instrument panel. See Figure. Install Jumper Wire (SST 09843-18040) between terminals No. 4 (CG) and 13 (TC) on data link connector No. 3. See Fig 1. Go to next step.
  4. Start engine and note engine speed. Engine speed should increase to 1000 RPM for 5 seconds and then return to idle speed. If engine speed is not as specified, test IAC valve resistance and IAC valve operation. Go to next step. If engine speed is as specified, remove jumper wire. Turn ignition off.
  5. To test IAC valve resistance, ensure ignition is off. Disconnect electrical connector at IAC valve. IAC valve is located on lower area of throttle body. Using ohmmeter, checking resistance between +B terminal and each remaining terminal on IAC valve. See Fig 2.
  6. Replace IAC valve if resistance is not within specification. See IAC VALVE RESISTANCE  table.
  7. To test IAC valve operation, remove IAC valve from throttle body. See THROTTLE BODY under FUEL SYSTEMS in REMOVAL & INSTALLATION - V6 & V8 article. Apply battery voltage to +B terminal on IAC valve. Apply battery ground to proper terminal and ensure valve opens and closes. See Fig 3. Replace IAC valve if defective.
  8. If IAC valve resistance is within specification and operates properly, check wiring circuit between Engine Control Module (ECM) and IAC valve. For illustration of ECM location, see Figure. See ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS article in ELECTRICAL. If all components and wiring circuit are okay, but idle problem still exists, the air assist system may be defective. For testing of air assist system, see AIR ASSIST SYSTEM .
IAC VALVE RESISTANCE

Application Ohms
Tacoma
Cold (1) 17.0-25.0
Hot (2) 21.5-29.5
(1) Cold is with temperature of 14-122°F (-10-50°C).
(2) Hot is with temperature of 122-212°F (50-100°C).
Fig 1: Identifying Data Link Connector No. 3 Terminals (Tacoma)
G99C52821Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
Fig 2: Testing Idle Air Control Valve Resistance (Tacoma)
G96J09948Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
Fig 3: Testing Idle Air Control Valve Operation (Tacoma)
G95C34431Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
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