Inspection Procedure

HINT:

If there is an open or short in the engine coolant temperature sensor circuit, the ECM outputs DTCs. Perform troubleshooting with the SFI System. See HOW TO PROCEED WITH TROUBLESHOOTING (1MZ-FE/3MZ-FE), HOW TO PROCEED WITH TROUBLESHOOTING (2AZ-FE) or HOW TO PROCEED WITH TROUBLESHOOTING (2AZ-FE (Partial Zero Emission Vehicle)).

1. READ VALUE OF HAND-HELD TESTER 
   1. Operate the hand-held tester according to the steps on the display and select "DATA LIST".

   ECM: 

   DATA LIST SPECIFICATION TABLE - ECM
   
   

   Item	Measurement Item/ Range (Display)	Normal Condition	Diagnostic Note
   Coolant Temp	Coolant temperature/Min.: -40°C (-40°F), Max.: 140°C (284°F)	After warming up: 80 to 95°C (176 to 203°F)	If the value is "-40°C (-40°F)" or "140°C (284°F)", sensor circuit is open or shorted.

   OK: 

   Coolant temperature displayed on the tester is between 80°C (176°F) and 95°C (203°F) after warning up. 

   NG: GO TO ENGINE CONTROL SYSTEM (See  HOW TO PROCEED WITH TROUBLESHOOTING  (2AZ-FE),  HOW TO PROCEED WITH TROUBLESHOOTING  (2AZ- FE(PZEV),  HOW TO PROCEED WITH TROUBLESHOOTING  (1MZ-FE/3MZ-FE)) 

   OK: Go to Next Step 

2. INSPECT COMBINATION METER ASSY 

   INSPECTION USING OSCILLOSCOPE 

   1. Remove the combination meter with the connectors still connected.
   2. Connect the oscilloscope to terminal C7-36 and body ground.
   3. Start the engine.
   4. Check the signal wave form according to the condition(s) in the table below.
   Fig 1: Identifying Combination Meter Assy Terminal C7-36
   Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.
   COMBINATION METER ASSY - REFERENCE TABLE
   
   

   Item	Condition
   Tool setting	5 V/DIV, 10 ms/DIV
   Vehicle condition	Ignition switch ON

   OK: 

   As shown in the illustration 

   Fig 2: Identifying Signal Wave Form Graph

   Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.

   NG: REPLACE COMBINATION METER ASSY (SEE  OVERHAUL  ) 

   OK: Go to Next Step 

3. CHECK HARNESS OR CONNECTOR (BETWEEN WATER TEMPERATURE RECEIVER GAUGE AND COMBINATION METER ASSY) 

   NG: REPAIR OR REPLACE HARNESS OR CONNECTOR 

   OK: GO TO ENGINE CONTROL SYSTEM (See  HOW TO PROCEED WITH TROUBLESHOOTING  (2AZ-FE),  HOW TO PROCEED WITH TROUBLESHOOTING  (2AZ-FE(PZEV) or  HOW TO PROCEED WITH TROUBLESHOOTING  (1MZ-FE/3MZ-FE))