i would like to find a good source for 12 volts to power my gauges.
what i really want to do is find a good 12 volt hot when running and
starting. Then run that to a relay, then relay to ground. then run a fused
line from the battery to relay, then to a power brick. that would be the
central power source for all my gauges.
what wire or wire color would be the best to trigger the relay and where
could i find it.
Thoughts or opinions?

Thanks.

1979 351M C6

 

The wire is orange with a white stripe it is behind the gauge panel and has a yellow 3 prong connector you will have 2 open prongs the third prong is used to power the wipers.

 

There's a 12v switched source at a 3 way female connector (i believe it's yellow) just under your headlight/wiper switch that you can be tapped into for accecories.

 

There's a 12v switched source at a 3 way female connector (i believe it's yellow) just under your headlight/wiper switch that you can be tapped into for accecories.

I'v looked and looked for this plug, was it in all models?

 

I have no idea but i assume so, i've had one on all my 73-79's that i can remember, perhaps yours was cut out by a PO, it's a 3-way female bullet connector and it's generally unused by the factory unless you have intermittent wipers or cruise control, it's a conveinent 12v source for a tach, lights, radio, etc.

 

You can always tap into your ignition wires if you're just using it to trigger a relay. Not sure which color is the correct one but a meter will let you know. You'll have a constant 12v, Acc, On, and a starter wire.

 

Just putting this back up in the queue after a decade. Super helpful - I didn’t know the 3-pro g switched source was hiding up there. Thanks.

 

12 V keyed power.

Also there is a black 3 prong constant 12V behind the glove box/,left hand side area. That is what powers the glove box light and the cig lighter via a splitter.