96 ECU in a 98 - getting rid of P0136 (long)

[eng92]

This may be common knowlege but I did not see it in the stickies.

There are two basic steps involved:
1) On the ECU connector, move the wire from pin 107 to pin 105.
2) Change out your 4-wire zirconia type rear O2 sensor for a 3-wire titania type.

- EDIT -
also must add rear O2 sensor signal ground from ecu pin 112 to engine grounds F18 and F19 on intake manfold collector.

From previous posts I have read, it seems that most people are aware of step 1 but do not carry out step 2.

Please be aware that you cannot sub a 3-wire zirconia type sensor in place of the 3-wire titania. The two types work completely differently.
The zirconia type generates a voltage depending upon O2 levels. The ECU expects to see a fluctuating voltage from 0-1.0 V.
The titania type sensor changes in resistance depending on O2 levels. The ECU measures the voltage drop across this resistance. It expects a voltage fluctuating between 0-2.2V.
If the ECU does not see the specified voltage fluctuation after a given time period, it will throw the P0136 code and give you a CEL.

Some of you may have discovered that the rear O2 sensor bung on a 98 is an 18mm thread while the one on a 96 is 12mm.

There are three options for sensor replacement:

1) Buy a 12mm, 3-wire titania type for a 96 and machine an adapter for it to fit the 18mm threaded bung.

2) Weld a 12 mm bung on your exhaust and use the 96 sensor.

3) Buy an 18mm, 3-wire titania type sensor. Easier said than done. Not used on any North American production cars that I am aware of. NTK Europe makes them but NTK North America does not. All of the 3 wire titania ones over here are 12mm.
I believe I found one through Oxygensensors.com. It is Walker p/n: 250-23881. It is a universal type, so you will have to cut the connector off of your factory sensor.
Don't anybody go out and buy one just yet. Mine should be arriving monday or tuesday. I will follow up after I get it installed to confirm that it does the job.

I know someone is going to ask the question: Will this work on a 99???
Short answer: I do not know.
Long Answer: I know the 99 uses a four-wire 18 mm zirconia type like the 98. The nissan p/ns may be different but that just means the connector or length of wire attached to the sensor is different. You would be replacing it with a universal so that does not matter.
I have FSMs for 96 and 98, not 99. The pin-out on the ECU may be different. If someone wants to supply me with the schematic for the rear O2 sensor circuit, I can let you know.

I apologize for the long post, but since there is a GD for JWT ecus going on right now, I figured this would be useful info for some of us 98s.

[Sentinal]

Sounds like good info. Im probaly going to buy a 96ecu for the GD. Thanks for posting a detailed problem solver for the CEL.

[Zack342]

i copied and paste your post into this thread http://forums.maxima.org/showthread....=1#post3341014

one of the guys with a 99 had technosquare look at out ECU's and apprently it is the same of very close ot the 98. if you don't mind taking a look at the thread and sharing any other information you might have it would be appreciated very much. thanks

[spindation]

Great Info. Thats what i was missing. Thanks alot

[JSutter]

sweet maybe someday!

[Toolrocks]

Glad I saw this. I too am having the same problem and was notciing the pin out difference between the ECU years. Great info - I can't wait to see how your new O2 works.

[eng92]

- UPDATE -
new O2 sensor finally arrived on friday - installed it sunday night
Problem - I am not picking up any voltage output from it on my OBD2 scanner.

A quick check of the 96 ECU schematic reveals the problem. The ECU requires a separate signal ground for the rear O2 sensor to be on pin 112.
Damn 3 wire sensors - the four wire types have a built in signal ground so no separate wire is necessary.
Time to hit the wrecking yard again. Probably the best place to get some of those "fancy" female terminals that go inside the ECU harness connector.

I'll keep you all updated.

[eng92]

- UPDATE -

NO MORE P0136 CODE

tied the rear O2 sensor ground (pin 112) over to GND C (pin 32) on the ECU. I realize there is the possibility of creating a ground loop by doing it this way instead of running a separate wire all the way to the F18 & 19 engine grounds the way Nissan did in 96.
Without a scope, there is no way to tell how much if any additional noise is being added to the signal. The voltages I have monitored so far are all within the specified range of 0 - 2.2 Volts.

Well one code down, one more to go. I still have the P1220 FPCM code.

I have all the parts and the section of wiring harness I need to splice into the 98 factory one. This should happen early this week.

[eng92]

- UPDATE -

CODE P1220 GONE AS WELL

CODE FREE AND READY FOR EMISSIONS TESTING

Wired the FPCM and dropping resistor in on Saturday. Had to tun two new wires from the ECU to the left rear quarter where the modules are located. Some minor re-wiring of the body grounds and fuel pump were also required.

For all you 98s, this step should only be necessary if you have a 95/96 ECU out of a cali-spec or Canadian maxima and are getting the P1220 code.

Spare '96 ecu will arrive at Technosquare today.

For any of you 98 cali-spec owners looking to convert to a 95/96 ecu, I have a whole harness full of ecu pins available. I can pop a couple in an envelope with ~24" of wire attached and mail them out.

PM me if you need some or have any questions concerning the re-wiring.

[Toolrocks]

so, you said you re-wired some grounds. I assume that meant the rear O2's as well? In any event, great thread and congrats on the emissions.

[Kevlo911]

Wow that is great, you should tell a mod to clean this thread up and put it in hte stickies.

[Jar]

Awsome news! I was wondering when some info like this would pop up thanks very much! now just to make sure there arent any differences in canadian vs US electronics are they?

[nismos14]

Originally Posted by eng92

This may be common knowlege but I did not see it in the stickies.

There are two basic steps involved:
1) On the ECU connector, move the wire from pin 107 to pin 105.

Can this step alone remove the CEL?

[eng92]

Originally Posted by nismos14

Can this step alone remove the CEL?

No, the 96 ecu needs to see the higher voltage variation (0-2.2V) that you get from a titania sensor. THe 98 stock zirconia only varies 0-1V.

[nismos14]

ahh this just confuses me more i think lol

[nismos14]

When swapping the pins, does the wire in the 105 slot go over to the 107 slot?

[eng92]

Originally Posted by nismos14

When swapping the pins, does the wire in the 105 slot go over to the 107 slot?

There should be no wire in the 105 slot on a virgin 97/98 EC harness.

[DandyMax]

Originally Posted by eng92

There should be no wire in the 105 slot on a virgin 97/98 EC harness.

That's what I thought... mine only had 107, so I moved it to 105.

[Toolrocks]

Just bumping this to the top since I've read a lot of posts lately asking about this.

[eng92]

Just an update that may save some people some money.

Before going out and buying the titania 02 sensor:

1) On the ECU connector, move the wire from pin 107 to pin 105. There should be no existing wire in 105.

2) Ground ecu pin 112 (this is the rear 02 sensor ground)

I believe Dandymax just carried out the above two steps and it got rid iof the P0136 for him.

If it doesn't work for you, then you will have to buy the sensor.

[maximochka]

if any can please help me! I need to know how to pull out the middle part of the dash on my 96 gxe so i can mount a new deck with the pocket. I'm going crazy trying to pry it open I cam upstairs to find some help. I dont see any screws that I can remove what do I do. If you can help or even live in frisco e-mail with some how to's and pictures if you got any: akulat_34@hotmail.com

P.S. It's an open shell because the main deck is out for repairs and it took up two slots so whats left is the frame and the metal mounts.

[maxS]

good info; i've been thinking for a long time of doing the swap and already got a 96 i30t ecu...

[nismos14]

Originally Posted by eng92

Just an update that may save some people some money.

Before going out and buying the titania 02 sensor:

1) On the ECU connector, move the wire from pin 107 to pin 105. There should be no existing wire in 105.

2) Ground ecu pin 112 (this is the rear 02 sensor ground)

I believe Dandymax just carried out the above two steps and it got rid iof the P0136 for him.

If it doesn't work for you, then you will have to buy the sensor.

This worked for me as well

[Bonka]

Originally Posted by eng92

Just an update that may save some people some money.

Before going out and buying the titania 02 sensor:

1) On the ECU connector, move the wire from pin 107 to pin 105. There should be no existing wire in 105.

2) Ground ecu pin 112 (this is the rear 02 sensor ground)

I believe Dandymax just carried out the above two steps and it got rid iof the P0136 for him.

If it doesn't work for you, then you will have to buy the sensor.

Sorry for bumping this, but does anyone have the ECU pin and connector diagrams or have pics of which wire to move and to where?

Thanks.

[sergofast]

when you ground 112 do you tap into it and ground it or cut it and ground it (and if so which side? the one going to or away from the ECU?)

[nismos14]

Tap and ground should work.

[Kevlo911]

You want to ground ECU side, so it's up to you on how you want to do it

[sergofast]

what does that wire go to or do? Im afraid to tap something without knowing what it does for fear of hurting my ECU.