sirhk100

The motor I have was originally out of a '95 T100. It was previously installed in a pre-tacoma pickup that was raced offroad. The harness has already been converted and stripped down to bare minimum. The truck it was previously raced in ran no catalytic convertor. The harness has provisions for only one O2 sensor. My question, after looking around on here, all the trucks I'm seeing have a pre and post cat. O2. How is this harness setup to get around that? Also, the truck runs fine right now without at O2 plugged in at all. No check engine and no error codes on OBDii scanner. I know both are capable of working though cause I've had other codes and check engine light for other issues. I've got a O2 and bung to weld in pre-cat so I can get the harness plugged in. I'm going to take care of this single O2 for sure but just curious if anyone has any ideas how the previous owner would've got around not having a 2nd O2 after the cat since he didn't run one?

Thanks

sirhk100

So I was getting a couple O2 sensor codes so I finally welded in an O2 sensor bung and installed an O2 sensor to the single connector that was still on my harness. That took care of 2 out of the 3 codes I was getting but I'm still getting one code and I think it's cause there's no post cat O2 sensor. Looking at the wiring diagram pdf. that is linked in theMonch's post that's stickied at the top I only see one location for O2 sensor in the wiring. Where's the 2nd O2 post cat wire up to?

Am I completely lost? Nobody wanted to reply at all to this the when I posted this 8 months ago so maybe I'll still get no help but figured I'd try anyways.

ultimase

I'm not entirely sure so take this for what's it's worth. I know around 1995 was the OBD 2 conversion. I'm not sure when Toyota made this conversion, I'm more of a Nissan guy. Before this time I'm not sure there was a second o2 sensor, this o2 sensor is more for emissions to monitor the cat versus actual f/a mixtures.

What are the specific codes that you're getting?

sirhk100

Sorry, been a few days since I've been online... P0141 and a P0500 are the two I'm getting. P0500 is cause I have no VSS and no big deal... I've got the fix for that ordered and on it's way. The P0141 though is why I think I need a post cat O2. I have a brand new pre-cat hooked up. I was getting 2 other O2 related codes but those went away when I got the pre-cat one installed. I'll be doing a simulator though if I do a 2nd one cause I have no Cat in the system and actually don't have any room for one other then putting one in each down tube before my crossover...

Countryhick

i ran both o2 sensors im not even using a cat i dont have DEQ where i live but i used both just to run em incase i needed it. it runs great with both and probably run good with just the main o2 secon o2 is mainly to run the cat sensor.

sirhk100

Huh, that's interesting to know. Thanks for the feedback!

I'm still trying to figure out where the 2nd O2 wires into the ECU at. I'll look at the wiring again when I have a chance but I don't remember seeing anywhere on it regarding the 2nd O2.

I got my VSS piece in the mail yesterday though so I'll get that installed sometime in the next week or two!