So as soon as I turn my car on (not even the motor) the temp huage goes all the way up. If I start the car it stays up. Sometimes it wacks out while driving, if I rev the engine above 4,000 rmp the guage drops to zero until ot revs back down. WHAT'S THE PROBLEM HERE? Also my radiator fans don't come on. I have a d15b7 block which has a temp sensor on the thermostat housing instead of the back of the block. I spliced each wire and ran it to the new sensor. I connected the leads with spade crimps and slid them on the connectors

 

check your grounds or the sensor itself its a simple switch you can check with a multimeter

 

Check the back of your gauge cluster. It may have a burnt spot where it shorted out. I had similar problems on a 88 hatch and something had burnt a hole in the back of the gauge cluster and it melted part of the plug as well.

 

Where would the ground for this sensor be?

 

Change the sensor out.. It is a single wire on the right side of the cylinder head next to the coolant temp sensor