DTC 0908

The engine coolant temperature sensor is used to detect the engine coolant temperature. The sensor modifies a voltage signal from the ECM. The modified signal returns to the ECM as the engine coolant temperature input. The sensor uses a thermistor which is sensitive to the change in temperature. The electrical resistance of the thermistor decreases as temperature increases.





Engine coolant temperature °C(°F) / Voltage (V) / Resistance
(k Ohms)
-10 (14) / 4.4 / 7.0 - 11.4
20 (68) / 3.5 / 2.1 - 2.9
50 (122) / 2.2 / 0.68 - 1.00
90 (194) / 1.0 / 0.236 - 0.260

*:These data are reference values and are measured between ECM terminal (51) (Engine coolant temperature sensor) and ECM terminal (43) (ECCS ground).




CONSULT REFERENCE VALUE IN DATA MONITOR MODE




ON BOARD DIAGNOSIS LOGIC

OVERALL FUNCTION CHECK
Use this procedure to check the overall function of the engine coolant temperature sensor circuit. During this check, a DTC might not be confirmed.

NOTE: If both DTC P0115 (0103) and P0125 (0908) are displayed, first perform TROUBLE DIAGNOSIS FOR DTC P0115 (0103).

With Consult
(1) Turn ignition switch "ON".




(2) Select "COOLANT TEMP/S" in "DATA MONITOR" mode with CONSULT.
(3) Start engine and run it at idle speed.
(4) Check that the engine coolant temperature rises to 20°C (68°F) or more within 11 minutes. (Be careful not to overheat engine.)

OR

With GST
(1) Turn ignition switch "ON".
(2) Select "MODE 1" with GST.




(3) Start engine and run it at idle speed.
(4) Check that the engine coolant temperature rises to 20°C (68°F) or more within 11 minutes. (Be careful not to overheat engine.)

OR

No Tools
(1) Turn ignition switch "ON".




(2) Probe voltage meter between ECM terminal (51) and ground.
(3) Start engine and run it at idle speed.
(4) Check that voltage of engine coolant temperature changes to less than 3.5 (V) within 11 minutes. (Be careful not to overheat engine.)




DIAGNOSTIC PROCEDURE

COMPONENT INSPECTION

Engine Coolant Temperature Sensor




Check resistance as shown in the figure.




Temperature °C (°F) / Resistance (K Ohms)
20 (68) / 2.1 - 2.9
50 (122) / 0.68- 1.0
90 (194) / 0.236 - 0.260

If NG, replace engine coolant temperature sensor.