I beleive Bosch and NGK both ahve some O2 sensor wiring diagrams oin thier websites as they both offer some generic replacement O2 sensors.

If not goto the local parts store and ask to check the instructions inside on of the boxes

 

On most O2's one black is a keyed B+ and the other black is a ground. These are for the heater in the O2. I would have to double check at work but I think the blue is the signal to the pcm and the white is a ground for the signal side of the O2. Not 100% sure so you should wait and find out for sure.

 

From Gnob on this board

for the sake of explaination.
the colors in my post are main harness colors on the truck side of the plug


whte/red is heater b+ (should be key on power) connect to white
pink/green is heater ground. connect to white
black is o2 sensor wire. connect to black
brown is sensor ground. connect to grey

Worked perfect from my NGK Universal O2 Sensor

 

I used that wiring to put on some junkyard o2 sensor works great.

 

I moved mine from the #3 tube on my LCE header to in front of the cat to get a better reading. I was going to use a 4 wire sensor but to run the wiring was too much trouble so I used a universal 3 wire o2 as it was easier to install. Btw - 87 did not have 4 wire sensors, starting in 88 did Toyota use 4 wire sensors.

What I do remember is the following:
The Blue is signal + (the original o2 wire).
The White is the signal neg. wire and would go to the E1 on the ECU as it is for engine ground.
The two Black wires are batt +/- wires and should be hooked up to ign. switch. Do not connect the white and neg. black wires together.

 

I still run my on the header. A heated sensor works better, of course.
I use generics sensors from ford typically, as I buy 'em off ebay for $10-$15/ea

 

1988 4runner missing o2 harness

I recently purchased a 1988 4runner buggy it had a broken o2 sensor and was routed under the seat. There wasn't the rest of the wiring harness running under floor trim. I found a large pigtail next to dside interior fuse pabel, that in turn is my question is there a missing harness that has ben discarded. If that is the harness does anyone know the wires in which i can connect to.

 

you may have found the cat temp sensor harness that they used on the carbureted trucks. all the O2 sensor harnesses I've ever seen on the 22re engines was always part of the engine harness that ran underhood and down the top of the transmission.

 

x2

OP was the floor of the buggy built from an 83-84ish or older Toyota?

 

This helped me: http://home.earthlink.net/~jcgebhart/o2sens.html

Blue to ECU
White to ground
One Black to 12V for heater element
other Black to ground for the heater element.
This worked for me.