I let my brain go on autopilot and when it got back in the cockpit it realized that in its absence, the hands had disconnected a 4-wire 02 sensor without marking anything down. Perhaps worse, the wires were different colors on each side.
This is what I got:
1980's 4-runner. 22RE
On the truck side we have:
Shielded grey wire
Brown
White
black with yellow
On the O2 sensor side we have:
Black
Black
Blue
white
Now whoever did this, helped us out a little, as the brown wire on the truck side got it's gender reversed from all the others so that one is a dead giveaway (it goes to the white wire).
I figure the shielded grey must be the hot side (5v?) that is going to "read" the exhaust, so maybe that goes to the blue (since its the only other color on there)? and maybe both those black wires are grounds to the sensor and sensor heater respectively?
Can anyone on here check my logic before I break something simple and have to order stuff?
Thanks guys.
Obligatory close up. Taken with cellular potatoe. Sorry
On the O2, black and black are the heater lines (which is odd, that color changed to white-white later), and the other two are signal and ground. No idea on the truck side.
The heater lines are 12V, the ground line just ground, and the other is a basic signal line. The sensor generates it's own 0-1V signal (that's how you tell the a/f), so there should not be a 5V signal wire to it.
Thanks Alfa. I'm glad I asked (since I figured both blacks to be grounds) I should be able to find a diagram that can fill in the blanks from here.
Cheers!
Found a diagram online via google image search. But I cant open the page in my browser as I get a warning when I try:
Grey goes to the ECU, brown goes to ground, black goes to the "diagnostics" plug in the engine bay, and white (actually white/red) seems to be the common voltage line for all the sensors. With Alfa's post in mind, my thinking is, white/red goes through the sensor and comes out on the grey side (and subsequently to the ECU). The black and brown wires make up the heater circuit with the black being the 12v and the brown being the ground.
In other words:
Truck Black to o2 black (+12v)
Truck Brown to 02 black (gnd)
Truck Grey to o2 blue (ECU)
Truck Brown to o2 White (+5V sensor line)
I'll hook the battery up and check tomorrow morning and let you know how big the fire was.
Cheers!
So I see the white/red line a little different- that's the common signal ground, and should not have voltage on it. And it's a slightly different ground than the heater ground that you also found.
One other note- I think this is a late 90's 4 Runner. There wasn't a second O2 sensor until 1996, as that's when OBDII forced it into existance. And the actual 4 wire O2 sensor was also in the early 90's. So between that, the powertrain is late 90's and not 80s. Other indicators are some of the other included sensors that would not be in the 80s.
I'm glad that wasnt just me. I was expecting the old single wire o2 sensor.
Officially this is registered as an '89, but I think the truck might be slightly older. I have no idea what the market differences were between europe and the US though, so when I see stuff like this, it doesnt surprise me any more.
It also doesnt have a catalytic converter either (I guess they werent required here until '92?). BUT the air injection system is still there. I thought that was kind of odd.
I've got a couple manuals at the house (at work now). I'll compare this thread to those books and see if we cant make heads or tails of things.
Good times.
