I started experiencing flickering engine heat light a few months ago and ended up flushing out the radiator, radiator lines, and changing the water pump but didn't fix the problem. When letting the engine warm up, the fan would eventially come on so it was good. I could also manually turn the fan on by shorting the contacts in the cable going to the radiator temperature sensor. I ordered a new radiator temperature sensor and engine temperature sensor and installed them. As soon as I started the engine the temp light would come on and stay on and the engine was cold. I compared the new engine temp sensor with the old one and found the old one was normally open and the new sensor was normally closed so I'm thinking when the engine is operating in the cool range the temp sensor is open and when it gets hot the sensor is closed causing the temp light to come on. Apparently the new sensor was defective out of the box or not the right part. I started experiencing the flickering light again this morning just a few seconds after starting the engine while cold and off and on during the 4 mile drive. Can anybody shed light on the proper operation of the temp sensors? Does anybody know if the engine temp sensor should be normally open with normal temperature and close with overheating. Anybody know what the engine temp sensor part # is? I ordered what is listed at Rocky Mountain but it didn't work Any input would be greatly appreciated.