164 V6 too hot light possible fix

[jonathan coates <alfa@domain.elided>]

I have sent this message to members and to the digest in the past, but
the subject will not die.
If your overheat warning lamp is on, then you have no path for the
electrical stuff to get to the body of the car. This is variously called
the earth or ground depending how fortunate you were in your birthplace.
A problem which I was informed about here on the digest is the
connection between the switch and the thermostat housing and the
earth/ground is and always has been problematic. Alfa, knowing all about
this, installed a small wire from the car body to the thermostat
housing. However, just to keep it interesting, they put it just
underneath a hose where you cant see it. If you find that yours is
disconnected, you will find a small screw, or worse still, a small screw
hole, underneath the hose which goes from the top of the thermostat
housing casting towards the front of the car.
If you get the car running and measure for volts between the cam cover
and the brass body of the switch for the overheat light and temperature
gauge sender you should find no volts. If you find volts then you have
found the problem. Trace out where the volts are and clean the surfaces
so that the electric can get where it should be.
The other place to look, obviously, is at the switch itself. If this has
died you can ignore the lamp until you can get a new switch/sender
assembly. The switch is the brass looking thing with two different sized
spade connectors on it, not the close by Bosch Motronic engine
temperature sensor which has a plug like the ones on the injectors.
Hope this helps
- -- 
jonathan coates

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