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Randall C
Randall C, ASE Certified Technician
Category: Car
Satisfied Customers: 12890
Experience:  32 years Foreign / Domestic Cars All aspects of Diag and Repair
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Isuzu Rodeo: I have a 1996 Isuzu Rodeo 3.2 4WD Manual transmission,

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I have a 1996 Isuzu Rodeo 3.2 4WD Manual transmission, which is different than auto trans O2 sensor locations.
Oxygen sensor wiring harness is all mixed up due to an incompetent mechanic not labeling them before disconnecting all 4 O2 sensors prior to unbolting exhaust.
I just need to know what set of colored wires goes to what O2 sensor in simple terms, as there seems to be some confusion on the internet as to bank 1 and bank 2 on this car.
I have 3 sensors on drivers side. one at manifold down pipe, one pre cat converter and one after cat converter. One at passenger side manifold down pipe. They are 4 wire plugs, all different colors. Please help me get the right order as i have replaced all 4 sensors twice and even got a wiring diagram from another mechanic on this site who still didnt give me the right order evidently and I still get the same codes, P0146 and P0151. Thanks. Right now its hooked up as follows: *passenger side down pipe, pink, blue, black ,red/blue. *Drivers side down pipe, red, white, black, red/blue. *drivers side pre cat converter, Green, blue, black, red/blue. * driver side after cat converter, Green, red, black, red/blue. Thanks again.
Hello, I am Randall. I have reviewed your question and working on it now.Sorry for the delay
Are all plugs in place? meaning have wires been cut etc or all orginal but just need what sensor is which?
Customer: replied 4 years ago.

all plugs are original and all O2 sensors are OEM Bosch with plugs. No pig tails. I just need to find out where each one goes so I can finally get them hooked up correctly and the engine light will (hopefully) quit giving me O2 sensor codes. Thanks

i had this info pulled, so please bear with me a little bit so I can locate and send again. I will return as quick as I can. thanks
Unsure why you have the layout you have. 100% bank 1 is on the passenger side. It's always where #1 culinder is./The diagram I have is below. however, if you want to use the electrical diagram instead,?i have listed all 4. each with the different wire color in each
B1 S1 = Pink wire
B1S2= Green wire
B2S1= White wire
B2S1= Red wire

so, the bank 1 = ( B1) are on the right side. bank 2 (B2) are on left side and behind the cat converter

Customer: replied 4 years ago.

You have B2S1 listed twice. Which wire goes to B1S3, red or white?

very sorry, B2S3 really winds up being B2 S2 so the Red wire. , sorry
Customer: replied 4 years ago.

That is exactly how mine are currently hooked up. I just put in a new sensor behind converter (B1S3 or B2S2), cleared code with my OBD2 scan tool and light came back on. code P0146 (no activity detected, bank 1 sensor 3) and P0151 (low voltage bank 2 sensor 1). Also, does your diagram indicate that B2S1 is Drivers side down pipe or before converter ? Im reading it as B1S1 passenger side down pipe, B2S1 Drivers side down pipe, B1S2 drivers side before converter, and B1S3 drivers side after converter. That is why its so confusing. There is only one sensor on passenger side, yet everyone says that is bank 1 when there are 3 bank 1 sensors and only 1 bank 2 sensor, which you say, is mixed in with the other bank 1 sensors on drivers side.

This is hard to follow. I am saying bank one is on passenger side. That is 100% You will have one on passwenger side in the down pipe, then? 2 on the drivers side perasy and then one after the converter
the one behind the converter is called bank 2 sensor 3 so 3 on drivers, 1 on passenger
i pulled the diagrams , electrial for the manul trans , double checked and sent the one wire color code for each location
Customer: replied 4 years ago.

Lets just stick to your diagram to prevent more confusion as it does not list a B2S3 nor does any scan tool. my engine codes list it as B1S3 . This doesnt seem to be solving my issue and according to your info, I have them in the right locations. where does your info say code 0146 and 0151 are and what else would cause those codes to be coming up after installing new sensors? The wiring harness and plugs are in good shape as far as I can see. No breaks or melted parts. nothing against exhaust. Is there a relay or fuse that could be bad that just happen to control those 2 sensors?

well. this is new information. you did not list codes. Sensor 3 is the one after the cat converter. I know they confuse this but this is the way it is. I ahve to pull the flowcharts for the codes. unsure at this time
without going back though all the post, what wire color is at the sensor AFTER the converter. I located some differnt information
Customer: replied 4 years ago.

Ok. these are 4 wire plugs and some have at least one same color,ie, green or red. you only listed 1 color per plug so I may not have them hooked up correctly since i just noticed that 2 plugs have a green wire for instance.


My after cat converter wires (B1S3) are green, red and black (i'll just list 3 wires because they all seem to have a red wire with blue stripe as the 4th).


The drivers side down pipe (B2S1) wires are red, white and black.


before converter (B1S2) are green, blue, black.


Passenger side down pipe (B1S1) are pink, blue, black.


maybe this will help. too may colors to try and keep is the diagram for the manual trans

Customer: replied 4 years ago.

Can you write the location under each sensor? B1S1, B1S2 etc.

The wiring diagram doesnt say. Thanks

bank ones, as we discussed, right side, passenger side so,,

you have 2 of them on say the passenger side, 1 and 2

drivers side? you have 1 and then the confusion?.

Bank 1 sensor 3 is AFTER the cat

2 on passenger side, as you see, one on drivers side and one after the cat.

Customer: replied 4 years ago.

I meant on the diagram but it is listed on there, it was just printed very small and I missed it.

Ok, now we're getting somewhere. My, B1S3 and B2S1 plugs seem to be reversed, as I thought. I'll switch them and see if it works and will update you. Thanks.

Customer: replied 4 years ago.

Problem, diagram lists 2 sensors with green and red wire when 1 should be green and blue. Also, it says the B1S3 should be red and white wires but that plug is no way near long enough to reach it. That plug is only about 3 inches long coming off the front of the wiring harness and will only reach B2S1 or B1S2.

then what plug is long enough to reach and wire colors?
Customer: replied 4 years ago.

all of the plugs will reach B2S1 and B1S2 but only the Green/red and green/blue plugs will reach B1S3

no plug has a white wire?. I will be out a for a bit today.. i promise when i return i will continue, we willget this. I am stopping at the shop and doing another check as well
Also, pls send the production dat, date made, its on the label inside drivers door jam
Customer: replied 4 years ago.

Yes, there is a plug with a white and red wires. that is the one that you said goes to B1S3 but it is too short to reach. Im wondering if this diagram is wrong because it differs from the one that the other tech on this site gave me. his have all the right plug colors but it was for an auto transmission and are labeled for different locations. Also, your diagram does not list a plug with a blue and green wire like mine has but instead list 2 plugs with red and green wires. it could just be a typo but i still need to know where that blue and green plug go.

Manufacturers date is November 1995.

Sorry, I havwe checked 2 other repair sources as well as a couple different years. Yes, I see the auto trans diagram, but teh manual trasn is different
Everthing still says the plug wit the white wire goes to the post cat o2 sensor
You say it will not reach
Trans was never changed correct?
I will contrinue to research this but for now,, I am not finding the solution
Customer: replied 4 years ago.
I bought car new off the dealer lot in 96. Transmission has not been changed. Did you find out where the red and blue wire plug goes or does none of the diagrams u have, list it?
sure, i have diagrams for the red/blue the problem is, the manual trans diagrams show. green/ red and 2 of them. i have checked factory daigram,s, online diagrams we use through 2 differrent suppliersd and all show the same and in about 3-4 different years
I think the next step is to see what wire goes to what pin on the ECM plug. Can you get to the ECm if we have to do this?
Customer: replied 4 years ago.
But does it show the blue and red on any of the manual trans diagram? I'm guessing not if all of them show 2 plugs with red and green. I'm beginning to wonder if this car has the auto trans wire harness and they changed the transmission at factory. Maybe a special order or something after the car was almost complete.
Is ecm under dash behind glove box, as usual?
Customer: replied 4 years ago.

But does it show the blue and red on any of the manual trans diagram? I'm guessing not if all of them show 2 plugs with red and green. I'm beginning to wonder if this car has the auto trans wire harness and they changed the transmission at factory. Maybe a special order or something after the car was almost complete. Is ecm under dash behind glove box, as usual?

back shortly
ok, first, You said you had the other diagram, thus why I have not sent so here it is, the first one is the AUTO trans, the second is the MAN trans.
Auto trans shows the blue wire
Man trans shows 2x green, Thi sis the problem
Does not matter as i have the fatcory diagrams. It is not a typo thus why I am trying to figure this out.
I thought we would go the ECM and check a couple things there

Pls look at BOTH diagrams I have included. You will then be able to see the problem at hand and what i am doing to help resolve.
I am here to help but I have to think out of the box on this one
You wires are NOT matching the diagrams. nor fro any in about 4 different vehicle years unless something with the trans or harness was changed

You are sayingt eh RED/ WHITE will NOT reach that back sensor. no way?


Customer: replied 4 years ago.

There is no way red and white will reach. plus the fact that I dont have 2 plugs with red and green. thats why I said, im wondering if somehow they put the auto trans wiring harness in at factory with the manual trans, thus all the confusion.

yes, I agree that tracing back to ECM is the way to go. is it under dash behind glove box?

get to the ECM when you have a chance. Click to upload information. Now,, I do have to step otu for a bit shortly but this tim,e if I miss you I promise I will see it when I return

tell me what wire colors ar int eh D12 and D13 terminals of the WHITE connector at the ECM

info coming next
click HERE to upload

Customer: replied 4 years ago.
It will be sat morning before I can look at the ecm. I will let you know what I find. Thanks.
hey, will be on ALL day on Sat except maybe for lunch. I think I can hone in on this with this information. You cam e to us because some of this you knew,, I am here to help and will, Its just odd right now. so? I have to take another approach
I have my best foot forward on this and will NOT drop the ball with you.
Let me know.


Customer: replied 4 years ago.

D!3 is green and D12 is blue on bottom row of white connector.


Thanks for staying with me on this. 3 auto shops and the isuzu dealer couldnt figure it out 9 years ago and Ive been trying to get it right ever since. all because a mechanic didnt label them before disconnecting them :(

I still have a feeling the harness is for an auto tranny, its the only logical explanation but I want to be sure. I dont want to melt the converter because of the sensors being wrong again.

I think I found the answer, finally, Have to re ask as not looking back, does the blue/geen reach to the back o2 sensor?
Customer: replied 4 years ago.

I think it will. Seems like I remember going back and forth between B1S2 & B1S3 and the red/green and red/blue plugs. I think I have it hooked to B1S3 now actually because I think it was a shade longer than the red/green plug but I wont be able to get under the car until the weekend. I work 10 hour nights and just got home and decided to uncover the ECM since it was a quick, clean job. I'll let you know what I find then.


What did you come up with if it does reach?



ok, yes a typo across the board on the wirting diagrams. I was able to locate some pinout information for the ECM, it clearly shows the BLUE wire for the Ho2s 3 as the the plug that goes to the back o2 sensor
so,, basically the plug with the BLUE wire goes to the post cat converter, the one in the far back

Customer: replied 4 years ago.

well, they all must be wrong then because, remember, it calls for the red/white plug to go there not one of the 2 "typo" red/green plugs.


So, based on your info, pin out, etc. what is the correct order?

Im pretty sure this is how I have it hooked up right now, but will make sure on Sat. Tell me if it is the same as what you are coming up with.


B1S1 : Pink/blue B2S1:red/white

B1S2: Red/green

B1S3: green/blue


If so, it doesnt match either diagram, Auto or Manual transmission.

The auto transmission is close but lists green/blue to B1S2 and red/green to B1S3. No wonder its so confusing.




ok, to start, how I know the blue goes to the rear o2 sensor, #3 (B1S3)

look at D12 and D13, under MANUAL trans

Forget the wiring diagrams, they are incorrect


Customer: replied 4 years ago.

No kidding on the diagrams, that was my point ;)


Glad we're figuring it out. Seeing that pin location makes me feel good. My next step was going to be, unplug one and wait for engine light to come on, then check code location and repeat 3 more times. No fun and waste of gas and time.

Do you have the rest of the pin legend showing the other sensors for manual trans?

Thanks for your patience and tenacity.

The way you labeled the hookups are 100% correct, below is the other chart but the only ones you will see manual trans is that darn sensor 3

Customer: replied 4 years ago.

ok. I will check it all out on sat along with replacing the final 2 sensors with new ones and let you know what happens.

BTW, do you know what the drive cycle is on this vehichle after clearing the codes, for it to go back into "ready mode". The state will not pass the emissions test on it until the ECM goes back into ready mode after clearing codes which is done by driving it a certain distance and every cars drive cycle seems to be different on this subject.

It varies and no published information but different speeds, hot engine and could take a bit to complete. I wish I had that info but do not
Randall C and other Car Specialists are ready to help you
Customer: replied 4 years ago.

I think that did the trick. I changed the 2 remaining sensors and plugged all 4 back the I had them in my last post. So far, no engine light after about 20 miles.

Thanks for hanging in there and helping me trace the correct wires.