An electrical question

[navmk4gti]

So today was connecting something in the car. I tried connecting via a fuse tap and using empty fuse socket from the fuse box. Checked volt meter was reading 12v. Great. But it would not power the box.

When connecting it off the cig lighter wiring .. which also gives 12v..it works fine.

Absolutely baffled as to why this is. First time was trying to tap off the fuse box. Watched many youtube vids looks like what i did was right and volt meter was confirming it.

Any ideas what it can be?

[joe6]

Did you check the power on the lead from the connector after fitting? I think that piggy back connectors (if that is what you used) need to be fitted with the correct orientation if fitted into a spare fuse socket in order to pick up the power supply.

[navmk4gti]

Yup so the wire has a fuse at the end and a power wire coming off it..then also has a black ground wire. I out ground wire on a screw..and connected the fuse to one of the empty slots that gives 12v.

When i then put the ignition on i checked with a volt meter and the power cable is giving 12v.

I am wondering if it is a bad ground would it still show 12v ?

Ill try another ground point