Though voltmeters are very good and useful devices in fact I have several, I think you will find the device linked to below to be rather handy.
Start with your house batteries... Make sure the light is bright when connected to teh positive and negative posts. If dim, recharge.
Move clip to chassis (Any unpainted metal part) and touch the positive post.. Still bright .. Good
Now move out along the positive wire(s) When you find a device, touch the terminal that the wire from teh battery is hooked to, Bright=good
Touch the other terminal of the same size.. Bright, GOOD, Dark, problem found.
When you no longer see the light, problem found.
HINT: every time you move the ground clip touch the last known good point to insure you have a good ground.
Test lamp on E-bayNote: You can get one today at most auto parts stores/departments, hardware and such no need to wait for shipping.
Home was where I park it. but alas the.
2005 Damon Intruder 377 Alas declared a total loss
after a semi "nicked" it. Still have the radios
Kenwood TS-2000, ICOM ID-5100, ID-51A+2, ID-880 REF030C most times