Hey all,
I have an 81 and just recently, the Add Coolant light started to come on about 20 seconds after the engine is started.

I figured it was probably the sensor. I replaced that but the light and chime still come on.

Does anyone know what else can cause the problem?

Thanks,
John

 

Well really stupid question time. Your coolant isnt low right? Its to the top of the radiator yes? Try this, disconnect the sensor (top of the radiator [for the archives]) and ground the harness wire. If the light and buzzer go out, then the sensor is bad.

 

Yes - plenty of coolant. I have replaced the sensor and that did not help.

I will try pulling the sensor wire and grounding it to see if that changes anything.

Thanks.

 

if gorunding it doesnt work, look for a break in the wire, i know mine is very fragile so.

 

a quick hi-jack here... if the one on top is the add coolant sensor, what's the one on the bottom?

 

Another thread jack - is there a way to test the coolant temp sensor? The one that plugs into the coolant pipe right after the thermostat.

 

Took the wire off and grounded it. That did not work. I guess I need to run a new wire and see if that fixes it. Maybe there is a break somewhere.

Thanks for the help,
John

 

Water temp switch for the emissions computer.

 

Thats for the choke. If the choke is working correctly, then its fine.

 

Trace the wire in the diagram and find the next disconnect and try grounding there. Its gonna be a PITA now to t/s and fix. Sorry

 

I once had a problem with the water lines running to the oil cooler (beehive). One of the hoses was kinked and not allowing water to flow correctly. My add coolant light kept coming on until I fixed the issue, even though the coolant levels were fine. Probably not your issue, but I thought I'd throw it out there. Good luck!

 

try the simple thing like i did replace the rad cap