only works connected directly? pics

I could use some help. I have a Cigarette Lighter Socket multiplier. It has 3 ports. It has a quick disconnect so that I can disconnect it when doing dash work. It is securely grounded to a frame post and tested for ground. I have it wired directly to the car's battery and there is an inline 10A fuse that is verified good. (I tried several) I can read 12.7 volts at the car's battery with a VOM. And, I get the same 12v at the connector. For reasons that are baffling me, it will ONLY work when connected DIRECTLY to the battery. Should I test the RESISTANCE of the wires?

1999 Dodge Caravan (is that even important in this case?)

No - because the resistance of the wires is obviously good since it works (off 12V). What other 12V supply are you connecting to? If it's the cig socket, do you require ACC (or IGN) for that, or is it a crappy cig socket connection?

Yes it is important. That is probably not a ground. Ground it to the actual chassis of the vehicle. Dodge is famous for having massive pieces of metal under the dash that are not grounded. How did you test the ground? Was there a load present?

With something plugged into one of the ports, use your volt meter and check the voltage between your ground connection and a known good ground.

X 2 with Mr. I use a known ground point or any bolt (clean off the paintwork) adjacent to a factory ground point.

I agree. To clarify, I interpreted "Should I test the RESISTANCE of the wires?" as meaning the Multiplier's wires.

--- Resolved -- There was another fuse holder under the hood. So this device has two inline fuses. One is ATO and the other cylindrical glass type. I had not checked the ATO fuse. The fuse holder had some scale(?) type oxidation and the connectors were loose. I pinched the connectors tighter and used NOLOX on them and that resolved the issue. So it was reading 12v but was not able to carry sufficient current to power the device. Thanks for all the replies. It is appreciated!

Glad it was resolved. Glad too I was on the right track - ie, is there 12V to the socket etc? (As to those other amateurs like IAAI and Howie - oh well, maybe one day... . )

Thanks pal an important reason to keep a meter with a load tester resistance how about an AVO Mk4 for testing CAN wires....