Alright, the key is on the ignition for like 10 seconds and then the add coolant on the logicon comes on and then a buzzing noise happens. It does this even when the car is on. My coolant is full so what is wrong, is my sensor bad? How do I make this buzzing stop? ohh yeah the car is an 88 gxl.

 

have you bled the air out of the system?

 

couple of possibilities 1) air in the system 2) you got a leak in the system 3) bad sensor

 

is the sensor plugged IN?..that would make it buzz.
if it isn't hooked up,or your coolant is low, or you have air in the system..OR your sensor is bad.

 

To check the sensor remove it from the top of the radiator and start the car. The buzzer should go off after about 10 seconds. Next, ground the tip (the part that goes into the radiator) of the sensor and see if the buzzer continues. If it does your sensor is working properly. If it is indeed working properly then your issue is "probably" bubbles in your coolant system which will need to bled out. If your radiator is stock there is a bleed screw located on the passenger side of your radiator. Don't use a Phillips screw driver even though it has a thread for a Phillips screw driver for it will likely strip it. Use instead a medium sized flat head screw driver and it will open up with ease and at the same time not strip the plastic thread. Open up the fill cap and pour coolant into the engine with the bleed screw removed. Fill until the coolant begins to pour out of the bleed screw opening. Replace bleed screw and start car with the heater setting set to hot. Continue to add more coolant until it is full and be prepared to place fill cap on before the coolant gets too hot and wants to boil over. If this doesn't solve your problem you could remove the coolant hose on the back of your throttle body and add some coolant through that hose.

 

ground out sen.

 

loll was gonna say the same, just ground it.