Troubleshooting electrical short

[cali_surfer]

It seems as if I have an electrical short on my '69. I installed a Painless wiring harness back when I restored this truck a few years ago. I've been having some funky problems, radio going off and on, turn signals slow to blink if at all, tach frozen at a specific RPM regardless of motor, etc. When troubleshooting electrical problems, and since the Painless harness has so many different circuits, can I put an electrical tester on each of the individual circuit fuses (showing ohms) to see what the problem is? Is that how its done? This happened Saturday night, blinkers started acting up, radio display went black, then tach froze. It was late, but I checked the battery voltage--was 13.7, went out of town Sunday and didn't even touch it, then today I just went outside and the voltage is 10.7....... so obviously there is some sort of issue I have to deal with.