I thought I had this worked out a few months ago, and now that I'm going to attempt doing this (again).
Hell, I made a big thread about it and that thread seems to have been deleted

Anyways, Secondary O2 sensor, hard-wiring to an OBD2 ECU harness.

I am pretty sure that I have this correct, but it would be great if someone could confirm this for me:






1 – GREEN
* Sensor Ground
* Less than 1.0 V at all times
* Tap to C18 ( Green / Black)

2 – WHITE
* Detects secondary heated oxygen sensor signal
* With throttle fully opened from idle with fully warmed up engine: above 0.6V
* With throttle quickly closed: below 0.4V
* Tap to A23 ( White / Red )

3 – BLACK
* Drives secondary heated oxygen sensor heater
* With ignition switch ON, battery voltage.
* With fully warmed up engine running: duty controlled
* Tap to A8 ( Black / White )

4 – BLACK
* 12 Volt Power
* Tap to B1 ( Black / Yellow )


-a


Modified by Achenar at 11:17 PM 7/20/2005

 

 

let me know if it works too

 

how whould u do that ot a obd 1 ecu can someone hook it up with the same info thx

 

Never mind, this is obd2

 

Spot on (for a 99-00 Civic).

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by EE_Chris &raquo;</TD></TR><TR><TD CLASS="quote">Spot on (for a 99-00 Civic). </TD></TR></TABLE>

That's what I like to hear

-a

 

Alright, just wanted to report 100% success.

So everyone swapping B motors into your ex-Y7 equipped chasis, follow the above

As a bonus, here's a few minutes worth of data logging of some hot O2 sensor on O2 sensor action!





I started logging from a cold start. So you can see the Primary starts warming up much faster than the secondary. This is because the cat takes a while to heat up and start getting rid of the garbage in your exhaust.

Every time the secondary voltage dips very low (below 0.6 volts) is when I stepped on the throttle, then let off it. This is the correct behavior you should see for voltage (according to Helm) once you get everything wired up as I've outlined above. I only datalogged for about 5 minutes, but if I left it even longer, you would see the secondary O2 leveling off at just above 0.6 volts, and fluctating up and down in a pseudo-sinusoidal period, similar to the primary O2.

Now go to enjoy yourself!

-a

 

Did this last month and followed the exact same diagram, works like a charm!

 

SWEET! I'm gonna try this.

 

OBD1 ECUs don't look for a secondary O2 sensor to begin with.

 

So I am doing a 'oo Si swap into my '00 DX hatch and I tried this wiring trick for my secondary o2 sensor.

I am still showing a CEL and the car will still not idle very well.

Any suggestions?

 

dang, where was this two years ago when I needed it??? haha.

Achenar - Do you know what CEL you're throwing?

 

Just researched how to get my CEL codes, will be looking at that tonight when I get off work.

I am praying that I am just throwing the one code for the o2 sensor and that nothing else is farked.

 

I am showing CEL code 65.

Listed as:
65 Secondary oxygen sensor heater wire (black wires)

So I doubled checked and all my wiring is connected to the right place on the ECU.

I will double check the wires are good tommorow morning.

Any other advice in the mean-time?

I do NOT want to get a new o2 sensor yet because I am almost 100% sure that the sensor is good because it was working in the car before I stripped out the engine etc.

PLEASE HELP

 

For anyone with the same problem, I disconnected my battery and restarted the car and the CEL was gone. So looks like it just needed to be cleared from the ECU

 

So, if I have a 96-98 ECU (I know it's a little different) but would I still tap into the same wires? (Like the white wire into A23 marked SHO2S...although I realize on my ecu it might not be A23.) Am I making sense?

 

I have a 00 CX with an ITR swap using a 99-00 Si Engine Harness. I run a Kenji OBD1 Ecu and adapter.

Our state inspections stations now require diagnostic port interface and my inspection is now due. I never wired up the 2nd o2 sensor since the OBD1 didn't recognize it. Your thread is the only one that seemed to be OBD2b relevant. I am going to install a 99-00 SI P2T ECU to get me by for the Inspection.

My question is this. When you say "tap" in your thread;
Example;

1 – GREEN
* Sensor Ground
* Less than 1.0 V at all times
* Tap to C18 ( Green / Black) &lt;------------------- HERE

Do you mean these just "piggy back" on existing wires by cut/splice/soilder? Or will I actually need to physically pin these wires into the ECU plug at some point? Due to the cold winter I havent been able to take my ECU out of the kick panel and physically look at the plugs. I'm sure that would probably help, but i'd rather ask your advice since you wrote the thread and have already done this once.

Thank you for your Help!

-J

 

I know this is old but im wondering the same.

Thanks,