3-58 FUEL SYSTEM (DFI)

Water Temperature Sensor (Service Code 14)

Water Temperature Sensor Removal/Installation

CAUTION

Never drop the water temperature sensor, especially on a hard surface. Such a shock to the sensor can damage it.

•Remove the throttle body assy (see Throttle Body Assy Removal).

•Free the heat insulation rubber plate [A].

•Disconnect the connector [B]

•Drain the coolant (see Coolant Change in the Periodic Maintenance chapter).

•Remove the water temperature sensor [A] with gasket [B].

•Replace the gasket with a new one.

•Tighten:

Torque - Water Temperature Sensor: 25 N·m (2.5 kgf·m, 18 ft·lb)

•Fill the engine with coolant and bleed the air from the cooling system (see Coolant Change in the Periodic Maintenance chapter).

Water Temperature Sensor Output Voltage

Inspection

NOTE

○Be sure the battery is fully charged.

•Turn the ignition switch OFF.

•Remove the throttle body assy (see Throttle Body Assy Removal).

•Disconnect the water temperature sensor connector and connect the harness adapter [A] between these connectors as shown in the figure.

Main Harness [B]

Water Temperature Sensor [C]

Special Tool - Measuring Adapter: 57001-1700

•Connect a digital meter [D] to the harness adapter leads.

Water Temperature Sensor Output Voltage Connections to Adapter:

Digital Meter (+) → R (sensor O) lead Digital Meter (–) → BK (sensor BR/BK) lead

•Measure the output voltage with the engine stopped and the connector joined.

•Turn the ignition switch ON.

Output Voltage

Standard: About DC 2.80 2.97 V at 20°C (68°F)

NOTE

○The output voltage changes according to the coolant temperature in the engine.

FUEL SYSTEM (DFI) 3-59

Water Temperature Sensor (Service Code 14)

•Turn the ignition switch OFF.

If the reading is within the standard, check the ECU for its ground and power supply (see ECU Power Supply Inspection).

If the ground and power supply are good, replace the ECU (see ECU Removal/Installation).

If the reading is out of the standard, remove the ECU and check the wiring for continuity between main harness connectors.

Special Tool - Hand Tester: 57001-1394

○Disconnect the ECU and sensor connectors.

Wiring Continuity Inspection

ECU Connector [A] ←→

Water Temperature Sensor Connector [B]

O lead (ECU terminal 9) [C]

BR/BK lead (ECU terminal 28) [D]

If the wiring is good, check the water temperature sensor resistance (see Water Temperature Sensor Resistance Inspection).

Water Temperature Sensor Resistance Inspection

•Refer to the Water Temperature Sensor Inspection in the Electrical System chapter.

If the reading is within the standard, but the problem still exists, replace the ECU (see ECU Removal/Installation).

Water Temperature Sensor Circuit

1.Meter Unit

2.Water Temperature Sensor

3.ECU