A
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C
D
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P
section
P 5
72 1098/1098S - M.Y. 2007 - edition 00
Electric system
Coolant temperature sensor
The coolant temperature sensor (6) sends an electrical signal to the engine ECU, which shares it with the instrument panel over
the CAN line. To check that the sensor (6) is functioning correctly, connect the DDS tester to the diagnostics socket of the ECU
and follow the instructions given under the heading “Guided diagnosis” (Sect. D 5). After making the correct selections from the
menu, read the value of the coolant temperature from the parameters shown on the tester display. With the engine completely
cold, the air temperature (also read using the DDS tester) should be similar to that of the coolant. With the engine hot and the
radiator cooling fan just activated, the coolant temperature should be approximately equal to the cooling fan activation threshold
(Sect. C 1.1). If these tests do not give a positive result, renew the coolant temperature sensor. If the DDS reads an error in the
ECU memory of the type “coolant temperature sensor short circuit or open circuit”, check the circuit connecting the sensor to
the ECU. If this circuit is not faulty (not broken, not shorted and not earthed), renew the sensor.
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