Cooling Fan do not come

:uhoh: Hello my 1996 impala ss , The coolin fan do not come On until I umplug the Temp. Sensor. I already changed wit 4 different ones. 1, of Advance, Two of the junk yard and 1 od the cheavy dealer, and still I have the same problem.
please some body tell my how I can fix the problem.
thank you Alpine09.:frown:

Don't know on these later models, but the earlier cars had a couple temp sensors. The ECM controls the fans on your car so if they work without that one sensor plugged in that tells you the circuits and relays are ok. Might ask this question on the Impala SS forum, guys there would have more knowledge of this particular car.

http://www.impalassforum.com/cgi-bin/ultimatebb.cgi?action=intro

The primary fan should turn on at about 228°F, then off at 220°. The secondary fan should turn on at a slightly higher temp. Unless the PCM has been reprogrammed, the fan settings are relatively high to maintain a more complete burn and lower HC emissions. Make sure the coolant temperature is adequate before you condemn a fan, relay, or PCM. Since they seem to work by manipulating the sensor connections, the fan motor, relay, and wiring are probably fine. Another thing to remember is that the instrument panel gauges are not higly accurate, lab-quality instrments. They are a relative indication at best - Simply part of a trim package. They should never be used for any serious diagnosis, which is why they are so crudely graduated. This is true of all models.

Unplugging the temperature sensor (CTS) should not turn on the fan, but should set a DTC. Unplugging the pressure switch for the A/C system will turn on the fans since it simulates high pressure in the A/C system high side and should cause the PCM to operate the fan(s).

http://www.impalaclub.com/naisso/forum2002/forum.asp?FORUM_ID=7