where are you measuring 5v?
the yellow/red is the 5v positive feed
the green/orange is the analog common (basically just 0v)
the light green/black is the signal wire back to the ecu. it lands on pin 8 in the grey connector.
if you probe light green/black to green/orange, you shouldn't get 5v. if you do, you may have a short between the yellow/red and the light green/black. if unplugging the baro sensor doesn't clear this up, try unpinning the yellow/red from the ecu grey connector pin 1 and check again. if it's gone you can check continuity between the yellow/red and light green/black with the ecu connector unplugged, then start unplugging connections in the harness till you get an open circuit.
that's all i can offer right now man.