Hi everybody. I've got one for you: I was fiddling with my oxy sensor (EL I6)and trying to find out which wire did what. Enyway, I found the 12v wire, (supply to element) and I found what I think was the return wire @ 0.67 volts up to 0.87 but when I tested the other wire, I got a reading of 0.05V. This last wire IMOH should be the earth, thus should have no reading.
Does this mean I have a minor short somewhere, and would it have an effect on the Oxy sensor reading. I tested the actual sensor itself, and had no contiuity between the A and C pins, but had continuity between the B and C pins. I didn't check A and B pins though.


Pins: B C


A



as you look at the plug.

Thorts and comments greatly appreciated

Bugger, the "picture" of the plug didn't work. The "A" pin should be directly under the "C" pin

Hi Creature.

Im unsure of which wire does which but a 3-wire HEGO should have

2 wires used for the heating element, one being

1 wire for the sensor itself....

As i understand it, the sensor itself is grounded through the exhaust and hence, through the common ground on the engine.

What model we talking here? I thought later falcons were a 4-wire oxygen sensor, with the additional wire providing a specific ground for the sensor.

If you want to test the output, whilst running, the sensor should be switching between 0v - 0.9v when engine is warm and in closed loop.

I'd imagine that the common ground would be used for the heating element, you wouldnt want to rely on that for the sensor ground

That's what i would have thought but...

http://minimopar.knizefamily.net/ecu/oxygen_se.html

I guess that's the reason they went to the 4-wire.... too much rubbish in the common ground from injectors... narrow band HEGO not an exact science at the best of times, lol.

The heater draws 30A so the 0.05V is from the slight resistance in the wires.

thanks for all the info. The sensor was running @ 0.1 to 0.87V max when the motor was hot, so I guess that it is working o.k. What SPORK says makes sense to me. I didn't test the ohmage of the wiring tho. I guess the common grd is what is causing the slight resistance too?

It's an 89 EL. I have been using an EF wiring diagram, as my diagram is unavailable at the moment. I think I need to see if the wiring is different.

Once again, thanks

EB-EL 4L all use same HEGO setup, so the wiring should be the same.