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 DIAGNOSTIC TROUBLE CODE CHART )".

1. READ VALUE OF INTELLIGENT TESTER 
   1. Warm up the engine.
   2. Ignition switch off.
   3. Connect the intelligent tester to the DLC3.
   4. Ignition switch ON.
   5. Turn the tester ON.
   6. Enter following menus: DIAGNOSIS / OBD/MOBD / ENGINE / DATA LIST.
   7. Check values by referring the table below.

      ENGINE: 

      NORMAL CONDITION CHART
      
      

      Tester Display	Measurement Item/Range	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 SFI SYSTEM

   OK: GO TO Next Step 

2. INSPECT COMBINATION METER ASSEMBLY 
   1. Check the input signal waveform.
      1. Remove the combination meter with connectors still connected.
      2. Connect the oscilloscope to terminal C9-8 and body ground.
      3. Start the engine.
         Fig 1: Inspecting Combination Meter Assembly

         Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      4. Check the signal waveform according to the condition(s) in the table below.
         ITEM CONDITION CHART
         
         

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

   OK: The waveform is displayed as shown in the illustration. 

   NG: GO TO step 3 

   Fig 2: Identifying Signal Waveform

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   OK: REPLACE COMBINATION METER ASSEMBLY 

3. CHECK HARNESS AND CONNECTOR (COMBINATION METER - ECM) 
   1. Disconnect the C9 and E5 connectors.
   2. Measure the resistance according to the value(s) in the table below.

      Standard resistance 

      TESTER CONNECTION SPECIFIED CONDITION CHART
      
      

      Tester connection	Condition	Specified condition
      C9-8 - E5-14	Always	Below 1 Ω
      C9-8 - Body ground	Always	10 kΩ or higher

   NG: REPAIR OR REPLACE HARNESS OR CONNECTOR 

   Fig 3: Checking Harness And Connector (Combination Meter - ECM)

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   OK:  GO TO SFI SYSTEM