I have a 1990 ranger, my O2 sensor connector is broke so now I have no idea of the relation of the orientation the connector plugs in compared to the wire colors (I can plug it in any way).




It seems all the wiring diagrams I've found Don't have the same colors as mine. I have a dark green with purple, black with light green, grey with yellow, and a solid black wire.





here is what prodemand had for a wiring diagram, it's the closest one I've found but I still don't have a orange wire.





here's what someone with a 91 had


so does anyone have theses same colors that can post a picture of their connector, or does anyone have a wiring diagram with these colors?

 

Looks like a Bosch O2 sensor
White wires are for the Heater
Black and grey wires are the sensor

List your wire colors
I see
green/blue?
grey/black?
black?
???

 

Yes it is Bosch, I know what those wires are for. It's the wires on the computer side of the connector I don't know. I did list my colors, it's after the first picture.

 

Yes you did list them, but in the middle of post and between pictures made it hard to find

 

Look at 1989-1991 Ranger 2.3l diagrams and all use the 2 Orange wires
Even up to 2001 there was an orange wire on the O2s

You have
dark green with purple
grey with yellow
solid black wire
black with light green

Test which one has 12v with key on, only 1 will, that's the Heater power
Key off
Test which one is a GROUND, thats the heater ground
These connect to the Bosch white wires, there is no polarity, its just a heater

The other 2 don't matter as far as which is which either, as long as one is connected to Bosch black wire and one to the grey wire, O2s generate their own voltage once they are heated above 650deg, and there is no polarity

 

thank you! i was gonna ask how to test which wires are which also

 

 

Alright so with positive on the battery using the ground lead to prove the wires with the key off:

Dark Green / purple has 9v
Black / light green has 12v
Black has 12v
Grey / yellow has 12v


And with the key on:

Dark Green / purple has 9v
Black / light green has 12v
Black has 12v
Grey / yellow drops to about 38 mv


so what does this mean? It appears more then one has power?

 

???

It would mean shorted wires to me

12v O2 heater power is key on only, or battery would be dead in no time

 

You need to test with the sensor unplugged.

 

...I was testing with it unplugged... The whole point of this is I don't know witch way to plug it in

 

So what's the next step I would even take with this. The harness is in good condition, I don't see how anything could have shorted out. Before the connector broke and it was connected to the old O2 the battery wasn't dieing.

 

Were you using the negative terminal of the battery for this test?

If you used the positive terminal of the battery I could understand your test results.


Because with the key off, and using the negative terminal of the battery, there shouldn't be power to any of the wires.

 

+1 ^^^

With key off, if your meter was connected to battery positive(by mistake) then I could maybe see those results, but the 12volt wire should have shown 0v in that scenerio

Maybe its not the O2 connector, lol, 2 of the wire colors don't match anything I can find for 1990, 2 orange wires were seen in all my diagrams and even in later years past 2000 used at least 1 orange wire on an O2

Meter set on DC Volts, 20vDC if available
Black probe on battery negative
Test Red probe on battery positive first, should see 12.3v to 12.8volt, then test each wire key off, then key on

 

I think that's exactly what I did, I'll test again later with the negative terminal. Its what the old O2 was plugged into, and I don't see anything else it could go to. Thanks guys

 

Alright so using the negative terminal is appears the grey/ yellow wire is heater power. But both the solid black wire and the black with light green are a ground.

 

Turn on the key and see if either black wires ground potential changes

My guess is the Black/green stripe wire is the Heater ground, which was common in the 1980s O2s and early 1990's it was a black/white stripe wire
The solid wire(no stripe), usually Orange, was the sensor's reference ground

To double check, if you have an OHM meter selection on Volt meter
Set meter to OHMs
Touch the two probe tips together
Display should change to 0 ohms, this means the two "wires" are connected together
Hook one probe to the solid black wire
On the TPS(throttle sensor) there will be a 3 wire plug, unplug it
It should have a grey/red stripe wire
Touch other probe to that grey wire
Should see 0 ohms, as the black O2 wire and grey/red wire are spliced together at some point to use the computer reference ground
Air temp sensor or ECT(coolant temp) sensor should each have the same grey/red wire as well if you want to confirm