O2 harness problems?

[mylesprimo]

I have a CEL light on my 93 fzj80, and it is registering a 28 code. I know that is one of the O2 sensors, but every time I reset it, it immediately comes back on. I heard that in this case the issue may actually be the wiring. I spent a couple of hours yesterday searching for the issue, and found that most of the protective housing on the bank closest to the transmission in severely deteriorated but the wiring looks decent. It is possible to replace the harness, and if so how extensive is it? Or could my O2 sensor be so junked up that it immediately sends the code? Thanks for the help.

[Brentbba]

I'd replace the O2 sensor. I've had to do that a few times on my '94.

[mylesprimo]

Is it possible to actually change the harness though? It seems as if it may need it.

[Brentbba]

No clue - a call or message to cruiserdan may answer that question.

[Grolar]

Tracking down the fautly wire and fixing it might prove less expensive, if you can do it yourself. Otherwise you should expect a hefty tab.
And x2 on the sensors. Essential part of debunking what is wrong with the circuit.

[ArmyFJ]

The most common problem with a sensor is a faulty connection according to the FSM.

My O2 sensor was messing up and it required a new one because the connector wires kept pulling apart.

[photogod]

Check the O2 with an ohm meter and that will tell you right away. Should be between 5-8 ohms to be good.

[Firedog]

Does the code set immediatly upon restart (after you have cleared the codes)? If so, then the problem is with the heater in the O2 sensor or the wires going to the heater. If it takes some time to set the code, then the problem is most likely in with the actual sensor.
I just finished tracking down a code 21 with my '93. It set the code immediatly upon restart. I found the wire deteriated to the heater side of the O2 sensor. The problem was about a foot away from the O2 sensor connection.
If you can't find info here on a '93 or '94 code 28, try code 21 (the other sensor)
The FSM has a pretty good diagnostic section on the O2 sensors, but it immediatly tells you that you need a new computer, I don't recall it even mentioning checking the wiring.
Here is a link to my code 21 problems
http://forum.ih8mud.com/80-series-te...code-21-a.html

Good luck

[photogod]

This is exactly I mentioned the ohm test. If the O2 sensor checks out you know it is somewhere in the wiring. This will save you hours of trying to find a bad wire, when there is none, when it is actually the sensor.

[mylesprimo]

My problem is on the 28 bank, if I hook up an ohm reader and find that it is faulty, then how do I get to the wiring that is above the transmission? Do have to pull of the dash and just find where the wiring goes to?

[hj60]

Call your local dealer and give them the VIN. Ask if it's subject to the O2S recall and if it's been done.
If not, at least you know.
If it is, and was done, then I'd bet a week's pay it's in the wiring. Warranty work tends to be shoddier than non-warranty. .)
Mine shorted on the front DS at 75 mph westbound. I dropped it in N and coasted a mile or so up the ramp. Blew the EFI fuse with no warning/CEL.
Anyway, they tend not to put the harness back up into the factory loom and clips.