Engine - Coolant Temperature Sensor/Switch: Testing and Inspection

ECTS
Measure engine coolant temperature using NTC (Negative temperature coefficient) element. The thermistor resistance of NTC element decrease in response to rise of temperature.

It's used in determination of basic fuel quantity and ignition timing at starting, determination of basic idle control duty at starting, fuel and cooling fan control, and emission gas temperature modeling necessary for controlling emissions.

ECTS Circuit And Output Features:

The measure at sensor malfunction is to take the initial intake air temperature as basic substitution value of coolant temperature and increase it up to max. 110 °C in the interval of 0.5 sec in response to the quantity of air.

In case of the intake air temperature sensor malfunction, first take the substitution value of coolant temperature at 20 °C and increase it up to 110 °C in the interval of 0.5 second by the air quantity.

In case of intake air temperature sensor malfunction during engine running, first determine a proper temperature before first finding the trouble cause, and then increase it up to 110 °C in the interval of 0.5 second by the air quantity.

Checking the sensor




1. Using Hi-scan







2. Using multi-tester
1. Remove the engine coolant temperature sensor from air intake manifold.
2. Soak the sensor part of the engine coolant temperature sensor to hot water and check the resistance value.

3. Replace the sensor if the resistance deviates from the standard value.

Harness Inspection:

Troubleshooting hints
If the fast idle speed is not enough or the engine gives off dark smoke during the engine warm-up operation, the engine coolant temperature sensor might be faulty.

Installation
1. Apply sealant LOCTITE 962T or equivalent to the threaded portion.
2. Install the engine coolant temperature sensor and tighten it to specified torque.

Tightening Torque
Engine coolant temperature sensor: 14.5 - 28.9 lb.ft (200 - 400 kg.cm)

3. Securely connect the harness connector.