how to dectect common ground with a multimeter

[alundra]

i want to know how can you tell which is the ground points using a multimeter..every points i measure either get nothing or 0 ohm.. even though i can tell which is the ground one by reading the trace line(mostly on simple gamepad)..but sometime this trick doesnt work on some controller, like xbox controller...thanks

[Sasquatch!]

I'm not sure if I'm reading your question right, but I think you're looking for the "continutity test" on the multimeter.

[spongebue]

generally you'd want a continuity tester, but 0 ohm = little resistence = probably ground, assuming the other point is ground, that is.

[alundra]

is there a continuity test option on multimeter? if so what is it lable as? there a guy told me while ago that if i get 0 ohms on the connection, then it mean the connection is good..but  that only let me know that whether my connection is good or bad..what i want to know is how to determine which is the ground point on the pcb...
i try to test a psx pcb, because it is easy to tell which is the positive and ground points..and either grounds or positive, i still get the same 0 ohm on all of them...so i really dont know how to determine the ground on xbox controller pcb...

[lusid]

If you don't have a known ground point as a reference, the multimeter will not help you. 

If you can find a pin-out diagram for the xbox controller connector, that should have a ground you can reference.  From there you can use the meter to trace it back to the PCB and find the ground.