Been a long time since I have been on here anyway I just picked up another 1st gen and I am getting it all tuned up for smog. So my question is what wire hooks to the O2 sensor. I have a chilton manual on the truck but it isnt much help says from Emission comp (1) I should have 2 wires a Br and S. I am just wondering if anyone out there has any knowledge of were the wire I need may come out of the fire wall, also what color is it suppsed to be thanks in advancce for any input on this

 

Come on guys need a little help here

 

i wasn't aware there were O2 sensors on the 20R equipped trucks from 79?


my '80 20R didn't have anyythinggg like that...although it wasn't Cali specs soooo lol

 

Yeah I'm pretty sure a 1979 20R is not going to have an oxygen sensor... Oxygen sensors are for EFI applications (22-RE) although I wouldn't swear they've never been put on a carbureted application.

 

if it is supposed to have one, then it's simply going to be for the Idiot light.

are you not smog exempt or something?

 

Ya I'm in central ca. So I'm not smog exempt. Trying to figure this out so I
Can try and get it smogged this weekend.

 

Just look on the exhaust pipe to see if you have an oxygen sensor in the first place. Do you even have a catalytic converter?

 

Yes the truck has an o2 sensor it's located on the exhaust manifold
Just before the down pipe flange. I would not be asking about the o2 wire location and color if the truck did not have one lol. So I have been searching other sites and studying the shop manual still can't find the wire. The manual I have shows that the truck is supposed to have the sensor. Starting to feel like a wild goose chase here. Also the truck runs but not well it runs and idles ok until it gets warmed up then it won't idle and there is black smoke out the exhaust. Just did new dist.cap rotor, pugs, wires, new fuel pump, cleaned out tank, new air filter, checked all vacum lines, new pcv, oil and filter fuel filter, so with all that I checked the fuel level in the sight glass and it's way high. So besides finding that illusive 02 wire. I now have a sticking fuel float. So instead of screwing around with the stock carb with s rebuild and all that. I am thinking of going with a weber smog legal carb anyone have experience with these? Are they worth the 4hundered plus pricetag? Or should I just rebuild the stocker? Thanks all

 

people will likely tell you to rebuild the stocker..that's what i did.

rebuild the stocker for cheap..and save up for the weber.





i remember reading someones thread...he had swapped a different motor into his 1st gen, and he found a loophole..and got it to where he was smog exempt. and he was in Cali...


are you sure that the exhaust manifold on the motor is the one that came STOCK with THAT motor?


check an FSM and not a cheapo manual?

 

Ok well I decided to rebuild the stocker pulled the carb off and took it apart the fuel bowl was surprisingly clean. Rebuild kit will be in tomorrow. Still no luck on the 02 wire. Anybody know where to get How to Keep Your Toyota 4x4 Alive for the Compleat Idiot? I have heard it's a great manual to have, but from what I have seen so far looks like it's out of production now. Or a source for a factory service manual?

 

If anyone has a copy of How to keep your Toyota 4x4 alive for sale let me know thanks.

 

The Oxygen Sensor wires go to the Emission Computer and the Check Emission Sensor Plug. The wire going to the Check Emissions Sensor Plug is S or Brown. If you find a Brown wire with a Black stripe, that is the wire that comes from the Emission Computer and goes to the Check Emissions Sensor Plug. If the check Emissions Sensor Plug is no longer there, splice the Brown and Brown w/ Black stripe together. My service manual does not give the color of the other Oxgen Sensor wire but the wire goes directly to the Emission Computer.

 

Quick update rebuilt the stock carb last night slapped it on this morning and the truck runs great so it seems the carb issues are resolved. Still no luck on the o2 wires though.

 

Suncomb1 were is the check emissions sensor plug located?

 

Pic of your manifold would help My 20r had no O2 sensor in the exhaust manifold . It had an CCo thermo sensor in the cat, for the Air injection system. That may be the emissions sensor the chilton is talking about. I was reading that 20R and 22R Exhaust will swap, so that could have happened? sounds like you have the sensor there but no wire to hook to it?

 

i have the same exact problem..... its a 22r manifold....

 

Very similar problem here with 81 Toy PU, 22R, CA emissions.

Has an oxygen sensor mounted in the header. Single wire from the sensor mates with a connector. After the connector the wire is black and goes somewhere...

Problem is I noticed the black wire was broken off 1 inch after the connector. I can't find the other end of the black wire anywhere - maybe it was completely ripped out somehow. Does anyone know where the broken end of the wire meshes into a wiring harness?

I've spent quite a while looking. Shop manual just gives a schematic, no physical locations.

 

Don't think there is one

 

There is an o2 sensor on the cail carb'd trucks didn't believe it till I saw it. To my knowledge it doesn't do anything but trip the engine light if the air fuel mix is wrong. Where that wire goes, I haven't a clue.

 

So you think the Ox sensor is a diagnostic tool only? Cuz the computer can't control the carb or anything else based on the input of the sensor?

So the sensor probably just triggers the CEL if the air fuel mix is wrong so you can find and correct the problem yourself?

This means it really could be disconnected and no one would know, correct?

I have a CA smog check coming up and I need everything to appear to be working properly. So maybe I just bury the broken end of the wire in a wiring harness and it would appear to be properly hooked up and pass the visual exam?