Best source of switched 12v behind the dash?
 

I need a source of switched 12v power behind the dash, to connect a Bluetooth audio aux input device. I had planned to tap the cigarette lighter, but apparently the gauges are easier to piggy back on. Can someone suggest a specific spot to look? 1988 coupe.

Any red/black to any gauge use a male/female spade to piggyback onto one.

brain fart. Nothing to see hear. Please move along.

I recently did this on my 71. However I ran a new wire to an open fuse at the box. I think I used the power window fuse. I highly recommend doing it that way so you do not have to cut up the harness. Also it is easily reversible that way.

I vote for the cigar lighter

Fair enough, but I wasn't going to cut anything. I have piggyback spade connectors that let you split things cleanly for cases like this. So this could be a clean two-foot run of wire rather than 6-8'.

What type of draw (amps) will the device have. That would determine the best circuit to tie into.
There is a smaller yellow wire coming off the ignition harness that you might want to use. Normally for the radio.
I wouldn't use the lighter circuit. In a lot of cars it is also the clock and interior light circuit and is the one that seems to fail melting the dash harness.....

It's a bluetooth receiver, we're talking milliamps of draw.

If that is all it draws, I would go with just piggybacking off one of the red/black switched power leads on the back of the speedo or tach. Or to the thin Yellow wire off the ignition switch. Whatever is easiest to route to from the device mounting location.
Add an in line fuse though just to be safe.

Thanks! Color of leads and gauge to use was the specific answer I was trying to get to :) Just to save myself time probing around and so forth. Hopefully I can get this hooked up in the next week or two.