[KenWittlief]

There is no place to get 3 volts from the robot RC or power system, unless you have something like the tether cable (RS-232 port) or maybe the link to the radio shorting to the chassis.

chances are you are getting a false reading - ifyou put a digital voltmeter on something that has very high resistance, you can pick up stray static and false readings on the meter. try putting something like a thousand ohm resistor across the voltmeter leads, and Ill bet your "3 volts" dissapears.

If by some chance it remains, then the only place I can think that it could come from is the radio cable from the RC. Does it run through the frame anywhere? is it possible it got pinched or sliced somewhere?

BTW - Im assuming you measured this with the black lead from the voltmeter on the negative (gnd) lead of the battery? another way to check for shorts to the frame is to unplug the batterys (both) and use the ohm meter part of the DVM - see if you have low resistance from the +12 or the gnd posts to the frame anywhere - it should be in the thousands or ten thousands of ohms -if you see <100 ohms to the frame from either one, then you have a shorted cable to the frame somewhere.