The light you speak of may flash from a malfunction in the circuitry, but I
would suspect otherwise. And although I have heard it serves as an overheat
warning light for the coolant, it seems redundant, when you have a temperature
gage that tells you what the coolant is doing. So I don't rely on that as a
function.

The light is a low coolant level indicator light. It utilizes the resistance
of the coolant between the two electrodes of the sensor in the coolant
expansion tank. If the sensor is in good working order, the sensor reads  IR
drop(voltage) across the resistence between the  electrodes  in the tank and
if proper by design parameters, the light goes out. If the coolant level is
low resistence goes to infinity and the light comes on....infinity is
certainly not a proper resistance. IR drop goes off the scale, and the light
comes on. If the mix of water and coolant is not the proper ratio, the IR drop
will not meet design parameters and the light will come on.

So, you must 1) have the coolant checked for the right density. 2) remove the
sensor and clean the two electrodes. 3) be certain the coolant expansion tank
is full and the coolant in overflow tank is at the proper level.

That should take care of the blinking light problem.

Other things to do:

If coolant has not been changed in the last year.....change it. Be sure it is
mixed in the proper ratio  ----  I believe it's 50/50.

Burp the cooling system well to get rid of any trapped air.

Change the sensing unit. They are under $10. No point in being chincy on this.

If this doesn't take care of it - you most likely have a circuit problem up
front, and for that I defer to someone more knowledgeable about that end of
things.

Good luck.

John Rodgers
88GL Driver

Woody Halsey wrote:

> Dear List,
>
> The overheat alert light in the water temp gauge of my 83.5 is flashing
> constantly, though the gauge does not indicate overheating and the coolant
> level is full. Could this be linked to the malfunctioning wiper switch?
> Other ideas?
>
> Thanks,
>
> Woody