After two years of using my AC to turn on my cooling, fans I decided to troubleshoot and eliminate the problem. Here are my symptoms:
Fans never turn on at low speed (ie 6 volts per fan in series). Fans turn on when using the AC or when the temp reaches 245 degrees (per FSM). To me this eliminates the fans and their relays circuits due to the fact the fans do turn on at 12V. The digital gauge reads a real low temperature (say 120 degrees with the fans on) when the ECT sensor is connected. If the sensor is disconnected, the temperature reads about 193 degrees and the fans turn on (haven't been able to determine which speed at this time. Will use meter to detemine if both relays are turned on which would indicate high speed). Any way the interesting and confusing pheomenom is why the temperature reads as it does with the ECT unplugged.
If I short the unplugged connector terminals, the fans will turn on immediately after letting the engine cool down. However if I let the engine cool and unplug the sensor, the temperatue will start to rise. WHen temperature reaches approxiatley 193 degrees the fans turn on. Where is the readings coming from if the ECT is unplugged? The ECT I am referring to is located in the water pump. I believe the ECT is defective because the entire connector rotates in the sensor body however it still does not explain why the temperature rises and why I don't get an error code to indicate the sensor is open. At least if I leave the ECT sensor unplugged the fans come on magically