Attention! Before starting the procedure, wait until the engine has cooled down completely!
The coolant temperature indicator device consists of a gauge mounted in the vehicle's instrument panel and a temperature sensor mounted on the engine block, directly under the ignition distributor (see illustration below).
1. If the gauge shows overheating even when the engine is clearly cold, you should check the wiring between the instrument panel and the temperature sensor for signs of a short circuit.
2. If the meter does not function at all, check the condition of its electrical circuit by quickly short-circuiting the wire going to the temperature sensor to ground with the ignition on (the engine should not be started). If the indicator needle deviates to the end of the scale, replace the sensor. If the needle remains stationary, check the wiring of the measuring circuit for a break.
Caution! Try not to touch the blades of the cooling system fan, which may turn on even when the engine is off!
3. If you are not sure that the temperature sensor is working properly, measure its electrical resistance with a cold and hot engine. The resistance of the sensor should change inversely proportional to the temperature measurement and with a cold engine (below 55°C) be about 140 Ohm. As the engine warms up, the resistance of the sensor should gradually decrease and at a temperature of 86°C reach a value in the range of 30÷46 Ohm.
4. To replace the temperature sensor, simply unscrew it from the engine and quickly screw a new one into the freed hole, the threads of which should be lubricated with sealant in advance. Be prepared to collect the spilled liquid. After replacing the sensor, check the coolant level, if necessary, make the appropriate adjustment (see Chapter Routine maintenance).
Attention! The temperature sensor must be replaced on a cold engine!