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Throttle Positioner (TP): Corolla

  1. Warm engine to operating temperature. Check idle speed and adjust as required. Disconnect hose from Thermostatic Vacuum Switching Valve (TVSV) port "M" and plug port. See Fig 1.
  2. Disconnect vacuum hose from Throttle Positioner (TP) diaphragm and plug hose end. Check that TP is set at 900 RPM. Adjust TP if not at proper RPM. Reconnect vacuum hose to TP diaphragm.
  3. Check that engine returns to idle speed within 2-6 seconds. Remove plug and reconnect hose to TVSV port "M". If TP does not function as described, test Vacuum Transmitting Valve (VTV), TP diaphram and Vacuum Switching Valve (VSV).
Fig 1: Corolla Throttle Positioner (TP) Comp & Op Parameters
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