Sebring cooling fan/ Please help

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I have a v6 2.5 98 Sebring, It has been a good car but I now have a problem I can not sort alone. The fan that cools the rad has stopped working, I have replaced the coolant temp sender unit. Whilst doing this I did notice that if I unplug the 2 pin conector from the coolant temp sender the fan will work but I loose the temp gauge. As soon as I plug the conector back in the fan cuts out no matter how hot the engine is.
I know that it has to be some sort of relay but I do not know what one or even where I may find it. I also have the service engine soon light come on, never had this before.
Many Thanks in advance.