DTC 0103

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
Engine Operating Condition In Fail-safe Mode
Engine coolant temperature will be determined by ECM based on the time after turning ignition switch "ON" or "START".
CONSULT displays the engine coolant temperature decided by ECM.

Condition Engine Coolant Temperature Decided (CONSULT display)
Just as ignition switch is turned ON or Start 40°C (104°F)
More than 4 minutes after Ignition ON or Start 80°C (176°C)
Except as shown above 40 - 80°C (104 - 176°F)
When the fail-safe system for engine coolant temperature sensor is activated, the cooling fan operates while engine is running.

DIAGNOSTIC TROUBLE CODE CONFIRMATION PROCEDURE
With Consult
(1) Turn ignition switch "ON".
(2) Select "DATA MONITOR" mode with CONSULT.
(3) Wait at least 5 seconds.

OR

With GST
(1) Turn ignition switch "ON" and wait at least 5 seconds.
(2) Select "MODE 3" with GST.

OR

No Tools
(1) Turn ignition switch "ON" and wait at least 5 seconds
(2) Turn ignition switch "OFF", wait at least 5 seconds and then turn "ON".
(3) Perform "Diagnostic Test Mode II" (Self-diagnostic results) with ECM.




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 - 1.00
90 (194) / 0.236 - 0.260

If NG, replace engine coolant temperature sensor.