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- 6 Sep 2004
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Toyota Yaris (2002) 1.0 petrol Mileage: 51,000
Problem: Engine fan coming on without reaching HOT
I am a bit bemused by this particular issue as the car is running well generally. The engine fan comes on about the time that the blue light (COLD) switches off. I thought originally that this could be caused by a problematic coolant temperature sensor but there is no EML light illuminating so presumably no OBD code is being raised. Also the engine runs very evenly throughout the range on a run up the motorway etc. (I understand the defective temperature sensors can result in the setting of a too weak mixture etc). The red light (HOT) never comes on.
Anyway, I intend to check the resistance of the sensor with a multimeter to see if it shows acceptable readings throughout the heat range. Looking at the pics below can anyone tell me the best way to pull off the sensor connector as it is very stiff? I guess I should try to squeeze the connector at its widest point and perhaps push towards the sensor and then pull it backwards to free it. (It has not been separated from the sensor for nineteen years so no surprise that it is stiff). Also I have a query about the bolt below the sensor and its purpose in text on the pic.
The car has air-conditioning which uses the same fan when switched on. Is it possible that this problem could be caused by a defective switch? It would appear unlikely, I guess, as the fan seems to cut in around the same time on each occasion. Maybe a relay could be problem here?
Thanks greatly for any help.
Problem: Engine fan coming on without reaching HOT
I am a bit bemused by this particular issue as the car is running well generally. The engine fan comes on about the time that the blue light (COLD) switches off. I thought originally that this could be caused by a problematic coolant temperature sensor but there is no EML light illuminating so presumably no OBD code is being raised. Also the engine runs very evenly throughout the range on a run up the motorway etc. (I understand the defective temperature sensors can result in the setting of a too weak mixture etc). The red light (HOT) never comes on.
Anyway, I intend to check the resistance of the sensor with a multimeter to see if it shows acceptable readings throughout the heat range. Looking at the pics below can anyone tell me the best way to pull off the sensor connector as it is very stiff? I guess I should try to squeeze the connector at its widest point and perhaps push towards the sensor and then pull it backwards to free it. (It has not been separated from the sensor for nineteen years so no surprise that it is stiff). Also I have a query about the bolt below the sensor and its purpose in text on the pic.
The car has air-conditioning which uses the same fan when switched on. Is it possible that this problem could be caused by a defective switch? It would appear unlikely, I guess, as the fan seems to cut in around the same time on each occasion. Maybe a relay could be problem here?
Thanks greatly for any help.