Voltage Drop and more

[stamp_licker]

Keep getting fault codes 24 and 35 in my ej'd L.Normally the car runs fine but every half dozen or so starts the check engine light comes on and it runs rough and drops No1 cylinder and codes 24 and 35 come up.Ive checked the relay and get about 12.9 volts but out at the plugs for the bi-pass air valve and the purge control solnoid and the o2 sensor i get 0.5 volts,these are on the one that relay circuit for power.The manual says battery voltage which i assume is somewhere between 12.5 and 13 volts.Should these pins/plugs be getting full voltage or is 0.5 volts ok?