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Home >> Toyota >> 1996 >> T100 Base, 2D Pickup, Standard >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - System/Component Tests - 3.4L >> Idle Control System >> A/C Idle-Up System
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A/C Idle-Up System

  1. Before testing A/C idle-up system, ensure hoses at A/C idle-up valve are not damaged or clogged. A/C idle-up valve is located at passenger's side front corner of engine, bolted to air intake chamber near throttle body and contains a Black 2-Pin electrical connector. See Fig 1.
    NOTE: A/C idle-up valve may also be referred to as A/C idle-up Vacuum Switching Valve (VSV).
    Fig 1: A/C Idle-Up Valve & Idle Speed Adjusting Screw ID
    G96D09945Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  2. Ensure idle speed is within specification with engine at normal operating temperature. See IDLE SPEED & MIXTURE in ADJUSTMENTS - 3.4L article. Apply parking brake. Place transmission in Neutral.
  3. With engine idling, turn A/C on. Install Jumper Wire (SST 09843-18020) between terminals TE1 and E1 on data link connector No. 1 located in engine compartment, on side of air intake chamber. See Figure.
  4. Engine idle speed should increase for 3 seconds and then drop to just slightly above normal idle speed and remain at this speed. If idle speed does not increase, proceed to step 6). If idle speed is within specification, proceed to next step.
  5. After 15 seconds, ensure idle speed does not increase more than 100 RPM than idle speed obtained in step 4). If idle speed increases more than 100 RPM, rotate idle speed adjusting screw on A/C idle-up valve so idle speed does not exceed idle speed obtained in step 4). See Fig 1. Remove jumper wire from data link connector No. 1. Turn A/C off.
  6. If idle speed does not increase as specified, test A/C idle-up valve. See A/C IDLE-UP VALVE  under IDLE CONTROL SYSTEM. If A/C idle-up valve operates correctly, shut engine off and proceed to next step.
  7. Remove passenger's side kick panel for access to Engine Control Module (ECM).
  8. Turn ignition on. Using voltmeter, check voltage between chassis ground and ECM terminal No. 10 (Black/Red wire) on A/T models, or terminal No 2 (Black/Red wire) on M/T models. See Fig 2. This is the wiring circuit to A/C idle-up valve.
  9. Voltage should be 9-14 volts with ignition on and A/C off. If voltage is not within specification, check for defective EFI main relay or wiring harness between EFI main relay and ECM. See EFI MAIN RELAY under RELAYS . See appropriate wiring diagram in WIRING DIAGRAMS article.
  10. If EFI main relay and wiring harness are okay, check ECM ground circuit. If ECM ground circuit is okay, substitute another ECM and recheck system operation.
Fig 2: Testing A/C Idle-Up Valve Voltage At ECM
G96F09946Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
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