Inspection Procedure

HINT:

Read freeze frame data using the hand-held tester or the OBD II scan tool. Freeze frame data records the engine conditions when a malfunction is detected. When troubleshooting, freeze frame data can help determine if the vehicle was running or stopped, if the engine was warmed up or not, if the air-fuel ratio was lean or rich, and other data from the time the malfunction occurred.

1. Check throttle control motor circuit. 

   PREPARATION: 

   1. Connect an oscilloscope between terminals M+ or M and E1 of the ECM connectors.
   2. Start the engine.

   CHECK: 

   Check the waveform between terminals M+ or M- and E1 of the ECM connectors when the engine is idling.

   OK: 

   1. Correct waveforms are as shown. 

   HINT:

   The waveform frequency varies depending on the throttle opening.

   Fig 1: Identifying Waveform

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   OK: Replace ECM (See  ENGINE CONTROL MODULE (ECM)  ). 

   NG: Go to next step. 

2. Check throttle control motor. 

   PREPARATION: 

   Disconnect the throttle control motor with the magnetic clutch connector.

   CHECK: 

   Measure the resistance between terminals 1 and 2 of the throttle control motor with the magnetic clutch.

   OK: 

   1. Resistance: 0.3 to 100 Ω at 20°C (68°F) 
   Fig 2: Checking Throttle Control Motor

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   NG: Replace throttle control motor with magnetic clutch (See  REPLACEMENT  ). 

   OK: Go to next step. 

3. Check for open and short in harness and connector between throttle control motor and ECM (See  HOW TO USE THE DIAGNOSTIC CHART AND INSPECTION PROCEDURE  ). 

   NG: Repair or replace harness or connector. 

   OK: Go to next step. 

4. Visually check throttle valve. 

   CHECK: 

   Check between the throttle valve and the housing for foreign objects.

   Also, check if the valve can open and close smoothly.

   NG: Remove foreign object and clean throttle body. 

   OK: Replace ECM (See  ENGINE CONTROL MODULE (ECM)  ).