Temp. light question on 65-69`s

Question on the temp. light on the dash,isn`t it suppost to light up when you turn the ignition key?i noticed mine doesnt light up at all so i checked the bulb it checked good,i replaced the temp. switch thinking it was the problem and it still doesnt light up,so i took a test light and grounded the wire that goes to the switch and the dash light lit up,so i`m thinking maybe the switch i bought was bad so i bought an NOS one one ebay,so i replaced it and it still wont go on?is it not suppost to go on?it goes on on my `67 when i turn the key and when i start the car it turns off,i dont understand whats wrong?any suggestions appreciated.
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That's a good question George, I'll go turn on the key and report back... all I get is the GEN light, but then again I'm not sure if the dash light is still connected, since there was already a 3-gauge aftermarket panel under the dash when I bought the car. I'm thinking it's not hooked up anymore, since the oil light is also not connected anymore.

 

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Guys,

As I recall, the temp light illuminates during the cranking mode, when the ign switch grounds the circuit. Unless things were much different on Buicks, my '68 Nova also illuminated the light during cranking only. Only the "gen" light illuminated during the ign "on" mode. Ray

 

With the switch on just my Gen light comes on. Then like Ray said when you crank it then the Temp light comes on.

 

on my `67 it comes on like you said only when u turn the key to go to crank the engine,but it wont do it on my `66?i changed 2 Temp. switches thinking the new one was defective,but the NOS one too?could it be the ignition switch?o No: o No:

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The circuits are separate. The cranking "prove-out" circuit is part of the ignition switch. The temp switch grounds the circuit from another path, but to the same point. Ray

 

ok just because i`m not too elecrtically inclined can u be alittle more detailed?

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Larry,its just a regular temp. switch with 2 prongs sticking out,its mounted on the manifold on 67-up cars but on 66-down its mounted on the head in the front,its suppost to go on when you turn the key right before the car turns over it shuts off,i think the ignition switch may be the culprit.

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Larry here is a pic of the switch.

 

i just installed the NOS ignition switch thinkin it may be the culprit but still no signal on the temp. light?o No:

 

I fixed my temp lights on the 64 not too long ago. There's a single black ground wire the hooks onto a spade lug on my ignition switch, its separate from the group of spade lugs where the main wiring bundle plugs onto. That may be the ground point that turns on the light when cranking. There's a pink 18 awg (skinny) wire from one of the switch wires that makes one side of the light hot. Grounding the other side with either the switch in START or the sensor in the head makes it light up. If it's not lack of ground on the switch then I'd guess a bad/bastardized wiring harness. I have wiring diagrams and a meter, wanna send me a plane ticket and pick me up at the airport?

 

I Fixed it,it was the ignition switch in the end,i replaced it with an NOS one but i didnt mount it so it wasnt grounded,after i mounted it the light went on when going to crank motor,all help is appreciated,thanks guys,:TU: