I'll be using an add-a-fuse to create a new circuit for a cig lighter jack to power accessories including esp a sat radio. (The existing jack / plug are too obtrusive for a full-time connection.) Am doing this rather than spicing into the existing circuit out of overabundance of caution (wires to the existing ciggy look pretty skinny).

Where should I run the ground to? I see some curved / fluted metal brackets holding up the dashboard... guess I could use those by drilling a hole into one and affixing a screw / bolt. Guess I'll have to do a continuity test to another known ground point though if I do that.

 

I'd try to find an existing screw to the car's metal structure behind the dash rather than drill a new hole. The ones holding the blower housing in place look tempting. A crimp-spade-fork connector would be a good idea rather than wrapping the wire around a screw.

 

Thx, I'm with you about not wanting to drill through the firewall. The threaded bolt you point to is pretty tough to reach but maybe doable. I half wonder though if that bolt is actually touching any metal... it almost looks like it's isolated from ground (not knowing what it's contacting on the other side of the firewall.

Anybody else got any places for where to tap into ground?

 

The existing outlet is 20 amp and should handle what you want. I have my heated seats on this circuit, GOS and my grill mounted LEDs

 

Installed. Steve244 there were other similar holding other corners of the blower housing closer to the center of the dash that worked like a charm and easier to get to... thanks for the tip. Black3sr didn't realize it was 20amps but I still had to mess with routing wires anyway so the add-a-fuse out fine. I can't believe you're tapping into those skinny wires at the cig lighter to heat seats!