I'd like to find Vth by mesh current analysis. Mesh A and B share a current source, so they're treated as one supermesh. What's the equation for this supermesh? Also, do I ignore the loop with the open circuit? Since there's no current flowing there... 2A = ib - ia Anyway, is this the right equation: +12V + ia(6Ω) + ib(6Ω + 4Ω) = 0? if yes, then my ia ends up being -32V/(4Ω) = - 8A ib = 2A + 8A = 10A And the Voltage across 4Ω (Vth) = ib * 4Ω = 40 V! But that's not correct, Vth should be 6V!