I know this has probably been asked somewhere else, but I have yet to get a clear answer. I have an 88 4Runner which I bought off of someone else. I am unable to locate the wiring connector for the oxygen sensor. When I bought the truck the wire on the sensor was just hanging. I cannot find where it goes. The guy I bought it has one, maybe a different year, that goes through the floor under the drivers seat, but I do not have a plug for it there. Does anyone know where the plug for this thing should be located and if you have any pictures that would be great. This is one of the last things that I have to get corrected and I have been beating my head on the wall for over a month about it.

Any help would be appreciated.

 

Your looking for the harness side connector for the O2 sensor??

Just what engine do you have ?? Is it the original engine??

Has it been cut off ??

My 88 pick up it comes out under the left seat between the Rocker and frame .

Goes over top the frame to the O2 sensor .

Has this section of floor been patched you might want to look under the left seat unless it was just cut off.

 

The truck has a 22RE, I believe out of an 1989 in it. Someone has doctored some of the wiring on it. I recently found the neutral safety switch bypassed and correct that. I am looking for the connector on the harness side. I looked under the driver's seat and found nothing, but I have not looked under the passenger side. The floor has not been patched as the truck is 95% rust free. Does yours actually enter the passenger compartment on the passenger side or just connected between the frame and the body?

 

Goes up under the left seat which is always the drivers seat

Kinda hard yours might be in the area before the back seat .

it should be a Yellow 6 conductor plug.

The thing with these things no telling what someone might have done

 

I have an 89 (Gen1) 4Runner, which has, from the factory, a mish mash of 88 and 90 model parts....

The OEM O2 on mine, has a rubber boot attached to the O2 wire. This boot seals a 1" or so diameter hole in the floor board. The CONNECTOR you are looking to attach to - is UNDER the carpet. If I recall (and is been a decade since I replaced one), the connector is UNDER the drivers seat.
You do NOT have to remove the drivers seat to get to the connector.
You DO have to un screw and pull up the plastic "door sill" trim that holds the edge of the carpet down.
Then you can flip the carpet back (there should be a connector there - in a 6" proximity to a 1-2" diameter hole)

 

I see no sign where anything was ever under the seat at all. I am wondering if there are differences between between the year models.

 

Mine enters the drivers side (as the exhaust is on the drivers side) right in the floor under the seat

22RE 4 cylinder engine

 

If the connector is under the drivers seat could you tell me where the harness goes from there? Maybe someone has removed part of the harness or something. The truck runs fine without it but that CEL is bugging the crap out of me coming on and off.

 

I have an 89 and the sensor is also under the driver's seat. I'm fairly sure the wires join a bundle that runs under the driver's door sill. That's why ewong said to check under the door sill.

 

I will tear everything back apart tomorrow and see what I can find. The original carpet is out of the truck so should be pretty simple. Anyone got a pic of the connector?

 

It's dark and my son drives mine. If you don't get a pic I'll take one tomorrow after 4 when he gets home.

 

Thanks Man. Much appreciated

 

I know I took a pic when we stripped the truck out last winter. Thanks Photobucket. I can't find it.

I found Terry87 had a picture that might help:

 

 

Your exhaust system is on the left side of the 4Runner ??

This is why I asked if the floor had been patched covering up the hole for the harness .

Your sure this is a 1988 ??

Was it by chance bought outside North America and imported by some one returning on Uncle Sam`s dime??

 

well the truck seems to be a combination of an 87, 88, and a 89. The body of the truck is an 88 and I believe the running gear minus the engine , the engine of the truck is an 89, and the shell on the back is an 87.

 

Ok. I dug into this some today. The plug under the drivers seat is not there. I checked my junk part truck which I know for sure is an 89 and it was there. Doesn't look like it was ever there in my good truck. Was there a different spot for the wiring harness plug for some other years?

 

In other years the O2 sensor plugged into a bung on the exhaust manifold. So the plug would be in the engine department.

 

I am thinking this truck has been bastardized. Anyone know which plug it could be under the hood? It has a 4wire near the Cat but I am thinking that maybe it should have a one wire since I can find no sign of the harness.

 

Now it comes down to figuring just what ECU and engine you have in there

86 and 87 had the 1 wire O2 sensor 88 is the year they went to the 4 wire

Look for a yellow signal connector with a black wire either just hanging or tied in the engine compartment

If I remember it runs from the left inner fender down to the O2 sensor