Coolant Temperature Sensor/Switch (For Computer): Testing and Inspection

TROUBLESHOOTING HINTS
If, during engine warm-up, the fast-idling speed is not correct, or black smoke is emitted, the problem is usually a malfunction of the coolant temperature sensor.

INSPECTION




Using Scan Tool




HARNESS INSPECTION
STEP 1. Check for continuity in the ground circuit.
- Engine coolant temperature sensor connector: Disconnected
OK: GO TO STEP 2
NG: Repair the harness. (A2 - 92)




STEP 2. Check for an open or short-circuit between the engine coolant temperature sensor and the engine control module.
- Engine coolant temperature sensor connector: Disconnected
- Engine control module connector: Disconnected
OK: GO TO STEP 3
NG: Repair the harness. (A1 - 83)




STEP 3. Measure the power supply voltage.
- Engine coolant temperature sensor connector: Disconnected
- Engine control module connector: Connected
Ignition switch: ON
Voltage (V): 4.5 - 4.9 V
OK: STOP
NG: Replace the engine control module.




ENGINE COOLANT TEMPERATURE SENSOR CHECK
(1) Remove the engine coolant temperature sensor from the intake manifold.




(2) With temperature sensing portion of coolant temperature sensor immersed in hot water check resistance. Standard value:
(3) If the resistance is outside the standard value greatly, replace the sensor.




(4) Apply specified sealant to the threaded portion.

Specified sealant: 3M Nut Locking Part No. 4171 or equivalent

(5) Install the engine coolant temperature sensor and tighten it to the specified torque.

Sensor tightening torque: 30 Nm (22 ft.lbs)