my car has a problem with killing batteries... it shows that my alternator is putting out only 7.4 volts out of a 15.5 it used to put out... i took it out to get a new one.... also my check engine light has a code for my coolant temp sensor... the problem will not go away.. i tried a new sensor didnt work.. what should i check... could it be my cooling fan relay... my fan comes on right when i turn my key to the on position and wont go off until it thinks it should... it makes my car run rough when its cold because my whole motor thinks its hot and its not.. any help would be appreciated..

 

Replace the coolant temp sensor and thermostat.

 

i have done that also... still the same thing.... i have checked the resistance on the sensor and it checks out with the chart. could it be a bad wire...

 

It could be. Or a bad relay and it is sticking on.