Inspection Procedure

HINT:

If there is an open or short the engine coolant temperature sensor circuit, the ECM outputs DTCs. Perform troubleshooting with the "SFI SYSTEM".

READ VALUE OF INTELLIGENT TESTER (ENGINE COOLANT TEMPERATURE SIGNAL)

Operate the intelligent tester according to the steps on the display and select "DATA LIST".

ECM

ITEM AND NORMAL CONDITION

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 display on the tester is between 80°C (176°F) and 95°C (203°F) after warming up.

NG : GO TO ENGINE CONTROL SYSTEM

OK : Go to next step

CHECK COMBINATION METER ASSEMBLY

Using an oscilloscope, check the signal waveform of the meter.

TESTER CONNECTION AND VEHICLE CONDITION

Tester Connection	Tool Setting	Vehicle Condition
C6-21 - Body ground	5 V/DIV., 10 msec./DIV.	Ignition switch ON

OK: Refer to the illustration.

Fig 1: Identifying C6 Meter Connector Terminals

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

NG : Go to step 3

OK : REPLACE COMBINATION METER ASSEMBLY

CHECK WIRE HARNESS (COMBINATION METER ASSEMBLY - ECM)

Measure the resistance of the wire harness side connectors.

Standard resistance

TESTER CONNECTION AND SPECIFIED CONDITION

Tester Connection	Specified Condition
C6-21 - E5-14 (THWO)	Below 1 Ω
C6-21 - Body ground	10 kΩ or higher

NG : REPAIR OR REPLACE HARNESS AND CONNECTOR

Fig 2: Identifying C6 Meter And E5 ECM Connector Terminals

OK : GO TO ENGINE CONTROL SYSTEM