I have a 1989 Pickup 4x4 (22re/ 5-speed) the truck is from California but the previous owner swapped in a non-california 22re from a 1990 pickup.

Currently I'm throwing 2 CEL codes (21 and 27) related to the rear O2 sensor... the problem is that I don't have a rear O2 sensor, nor do I even have a plug on the harness where I could install one.

So I'm wondering if I could just swap to a non-California ECU and make the CEL go away (I'd like the light to come on for legit problems instead of just being lit all the time).

I honestly don't know much about the computers for these trucks nor have I been able to find what I should be looking for when buying a computer unit.

Any help would be appreciated.

 

Yes you can because i did the same thing and it comes one for what it needs to and dose not look for the rear o2 sensor

 

awesome thanks...

I finally managed to find a list of ECUs here: http://board.marlincrawler.com/index...3954#msg123954

looks like 89661-35150 is the one I need.

 

All I can say is: "Be careful."

Just beacuse you're in NH and the truck came from Cali doesn't mean you can get away with "bypassing" Cali emissions: you may have to install Cali equipment so you can pass your local regs. Check your local/state body.

 

I've passed state inspection 3 times with this truck... pre-obdii vehicles are "visual only" meaning they pretty much look to make sure you've got the equipment installed.

The plot thickens though, as I just pulled the numbers off my ECU and it's a 89661-35160 meaning it's Federal Emissions but from a 2wd with a 4 speed manual. so now I have no idea why it's throwing cali only codes.

 

Have you tried replacing your O2 sensor? If you dont know how old it is I would replace it.

Have you tried unhooking your battery for a few minutes then connecting it back to see if the code comes back?

It might also be a good idea to find the correct federal version of ECU for your truck

 

Great question on the ECU. I've considered this on my California emissions '95 4runner. I've had the rear 02 sensor codes with CEL 'on' for a few years and even replaced the post-cat O2 sensor twice. ( I know... I need to replace my cat.) However, living here in PA....1995 (at least in Berks County) vehicles are considered pre-obd II and therefore have only a visual emissions inspection. I have researched here on the forum about the downside of running it this way. From what I learned, it appears that only the pre-cat O2 sensor will give engine feedback to change the engine properties (fuel mixture etc..pls correct me if I'm wrong) So - I have left the post-cat sensor and catalytic converter the way it is. So far, I have passed the emissions inspection for three years and my gas mileage has been about the same.

 

sperry u are right about that the 02 sencer be for the cat is the one your engine uses and the 2nd one is just to tell u if ur cat is working or not

 

I've cleared the code multiple times. and it keeps coming back (CEL comes on about 2 minutes after I start the truck). Also It's a brand new front O2 sensor, It's the first thing I tried after clearing the codes a few times, and of course I've cleared the codes a few times after installing the new sensor.

As for the ECU, if I had a cali ecu I would replace it, but since it's a federal one I'd rather not drop $100 on a new computer only to be exactly where I am.

I think my next step will be to verify that the harness between the ecu and front O2 sensor is actually good...

 

...is your CEL declaring a rear (post cat) code or a front (pre-cat) or both?

 

I know you mentioned both codes 22 and 27. I assume you already correctly followed sequence to clear the codes,..but it not.....
https://www.yotatech.com/forums/f2/odbi-37244/

 

yes, I've been using the procedure in the FSM to clear the codes.

 

Yep - Figured so....You likely have also thought of this,.....but one of the ideas I was considering was a mock (simulator) O2 sensor for post cat. The sensor sends the ECM the correct voltage so the ECM will be satisfied. Some folks on this forum have done it. You can actually buy one, or you can make your own. I wouldn't do it for the pre-cat since you need the feedback for motor performance. But, on post-cat, it may be better then buying a whole new ECM. Need to be careful legally since it's an off-road mod. Just google ' o2 sensor simulator toyota'

 

I considered that but my harness doesn't even have the wires to hook something like that up.... I would need to find someone with a trashed harness who could send me a few pins...

 

Does your truck have the Toyota mfr: California emissions sticker on the underside of the hood? On my California runner, the sticker says ' This vehicle conforms to US, EPA, and State of California Regulations......'

If it is, then it seems that your wire harness should have at least the stubs left from the original sensor wires....Unless your thinking that with the engine swap, they also switched wire harness? But if the harness was swapped, then you would think there would be other issues between the ECM and harness.

 

Chassis is an 89 4WD Cali
engine is a 90 4WD Federal
ECM is a 89 2WD Federal
harness is ??? (I'm assuming federal since it's missing the cali emissions connectors)

as for the rear O2 connector, I've checked my ECM connector doesn't even have the pins for that sensor... it's not just cut out it's completely absent from the harness, .