Jeep34

Jeep 2000 XJ
So both my upper and lower O2 sensors do not have power to the control part of the relay. There is power to the relay to heat the O2 sensor
but the relay is not getting power to the switching circuit. The wire schematic for my truck shows the fuel pump relay both use the same power source
but the fuel pump relay has power but my o2 sensors do not have power running to them. I chased the wires to the ecm and they are good.
From what the schematic is showing this does not seem possible. All three relays are right next to each other so I could imagine them all tied together
in the relay box.


I tried to break in to the relay box .... Under the relays but it does not seem to want to come apart.

Any thoughts on why I am not getting power to the Relay circuit.

emx72

I don'y know if this helps you, but maybe the wires are worn through by the drive shaft (my drive shaft ate through the 02 sensor) wires. Also maybe the fuse for the 02 sensors is blown.

Jeep34

Fuses good . O2 sensors good . Just no power to the control circuit of the O2 sensors.

jordan96xj

You are correct in your hunch to inspect the underside of the PDC. To ensure there isn't a moisture/corrosion problem under there. Continue in that direction to rule it out first. If you don't, you could bang your head on other stuff only to find yourself back at that point anyway. Especially when you have evidence that another relay control on the same circuit seems to have power (provided you are correct about that).