i have had an on going temp gage problem it does not work i started with replacing the sending unit then the instrument cluster as mine did not have a tach so i got one out of a automatic car that had a tach go figure well anyway it still did not work so i got into the wiring diagram found out i should have 5v signal at the sending unit which i did not have so i went through rest of harness and found a 5v wire and ran it to the voltage side of the sending unit still nothing so i checked the continuity of both wires to the ecu and found that the signal return wire was open so i re ran atha wire and still nothing now i am not 100% sure i had right wiring diagram as it came from auto zone and was under the 2.4 model but it was the only one that had right connectors and wires i do believe that it is the ecu itself i have another parts car which is also a 2001 2.2 but is an auto i am wondering if i switch the ecu and bcm as a pair will my car still run as i have heard that you cannot replace one without the other unless you program it which have no way of doing i have all kinds of time and not a lot of cash this is my daily driver to and from work miles a day and i do believe that the ecu believes the engine is ice cold it starts runs fine untill you stop shut engine down when i is ho then try to restart wthin 20 min then it hard starts and acts like a 2 stroke with fouled plug till you get it to rev up then it runs fine again i am not worried about the cel as it is on anyway but with the new ecu programed for auto tranny will this affect the engine contrls? any insight will be appreciated