Old post but....

If you're checking for continuity in a wire, you don't need to power it.
Select Ω (ohms) on the multimeter and connect one lead on either end.
If you get full bar that's good (unless there are resistors that will read as such or relays within the circuit that need a voltage source to close the circuit for a reading).

Not all electrical systems require 12v DC.

__________________
91 MBZ 300TE 4M 91 Jag XJS V12 94 Alfa Romeo 164 LS 80 BMW 320i 85 BMW 528e 86 BMW 325e 88 BMW 325e 88 BMW 325i 89 BMW 325ix 95 BMW 525i 96 BMW M3 78 Fiat Spyder 124 98 Land Rover D1 LSE 98 Range Rover HSE 4.6 93 MBZ 190E 2.6 96 MBZ C280 93 MBZ 400E 90 MBZ 300ce 71 MGB-GT 91 VW Corrado G60 97 328i 99 E320 Wagon 97 E320

https://lh3.googleusercontent.com/-t...r+sig+copy.jpg