Kevs02Accord

Hey guys I am trying to see if its possible to do an obd2b to obd1 auto conversion. This is for my 2002 accord. I will be using a 94 accord TCU and P75 ecu. I know someone who has done an obd2a to obd1 auto with success but the pins are different. So I need some help. I have attached an excel file with the obd2b, 94 tcu and p75 pins. I have attempted to show the connections from the obd2b to the ecu and tcu. There are several pins that I cant figure out were they go, can you guys take a look and see if you can match the missing pins. The list of missing pins from the obd2b pcm, 94 accord tcu and p75 ecu are listed at the bottom. Additional questions are;

1. With pins that have more than one connection is there 2 wires that come out for example obd2b pin A17 to TCU pin A22 and P75 pin A15?

2. Do I have to route any wires from one pinout on the ecu to the tcu and vise versa?

3. Will the missing pins from the p75 ecu and 94 tcu cause a malfunction?

4. Will the missing pins from the obd2b pcm cause a malfunction?

The obd2b pinouts were obtained from helms, the other pins were provided by the person who did the obd2a auto conversion. I feel fairly confident in the p75 pins, I verified them with several sites, however there are a few with some questions. I have not been able to confirm the tcu pins, so if anyone has those that I could check that would be a big help.

Any help you could give would be very appreciated.

despat

hi, wondering if you've done and succeeded. I'm also following the same instructions as you are however, they're not so clear. I've got a 97 Honda ODdy with a 94-96 JDM Honda Accord non-vtec auto transmission OBD1 2.2L engine in it. Currently running with original OBD2 ECU and obd2a harness (original), but not running well (jerky idle and misfires on all 4 cyl). I think if I were to use the p75 ecu with integra bin (with engine ignition map for F22B accord) and after making the harness, it'll solve the problem (if the problem was related to the missing Crank sensor when running obd2 ecu). Did you get this to work and finally get the harness figured out. I'd like if you could guide me a bit. I've already downloaded your attached file. Is it finalized. I mean, if I were to copy it, would it be fine or did you make some final changes?

Please help me. Ive not heard anyone (besides the original poster) actually confirm that this worked for them.

Thank you

despat

what is the format of the attached file. I can't seem to open it with anything?

Kevs02Accord

The should be zipped, I think I used winrar, its an excel 2003 file. Unfortunately I haven't made much progress. For me it comes down to either swap to an obd1 transmission, or use separate transmission controller. Both are pretty expensive. I have been working with Jason from rywire, he has been a big help, but unless there is some way to run a dual ecu/pcm setup the first two options are all I have.

I ll try to help as best I can. Firstly, according to the info I was basing my build off of, it is possible to convert an obd2a to obd1. That being said, you have an obd1 engine and transmission, however, I would double check that, I am not sure about the JDM accords but the USDM accord were obd1 for 94/95 and obd2 for 96/97. If in fact you do have an obd1 engine/tranny then I think the easiest thing to do would be eliminate the obd2 ecu and get an obd1, the p75 is a good option, it is also non-vtec, but that can be easily added to the ecu, you can also add vtec to the engine, not sure exactly on this process. The obd2 ecu is looking for and sending signals that it can not find, this is most likely why you are having all kinds of problems. An obd1 ecu should have no such problems, assuming your engine/tranny is obd1. Another thing to look into is the difference between USDM and JDM, you might need to pick up a JDM p75 or equivalent.

What kind of build are you going for? I hope some of this helps. Get some of that info and let me know.

despat

Hi,

My engine and tranny is JDM OBD1 and non-vtec, auto transmission. I don't think the differences betw the USDM and JDM versions are enough to merit different ECUS. The reason for making the harness is that it's auto so I've got to account for the TCU. The harness is done now and I've got

5 wires from OBD1 to TCU
27 Wires from OBD2a pins to TCU
44 wires from OBD2a pins to OBD1 (not 47 for so reason).

I'm waiting for the chipped P75 and I'll plug it in and let you know what happenes. As for the kind of build, i'm just getting the car to run smoothly with OBD1. As you mentioned OBD2 is more fussy and I'm running into probs.

Kevs02Accord

Well keep me posted, I would be interested to see how it goes.

Bird333

Make sure you are getting an automatic P75. Be sure to post back.

Kevs02Accord

Theres the man. How you doing Bird? Hope you don't mind me proliferating what little knowledge I have about the setup.

despat

Thanks Bird, nice to see you around. I'll surely need your help. Yes, it's an automatic P75. Will keep in touch.

Thanks

Bird333

Actually at this point you probably have more knowledge on OBD2b to OBD1 than I do. As you know, my conversion was OBD2a to OBD1.

despat

Ok so just connected to chipped P75 ECU/TCU and custom harness. The engine was cold and after connecting it the first time, it started fine and the RPM slowed down after the engine was hot. Only problem the car didn't want to move. When I shifted to D4 (or D3 or R), it moved very slowly and as if going to stall but didn't. I did see a check engine light but I couldn't check since I had take it down to the nearby garage. Well, So I repluged the orginal OBD2 ECU and drove it to the garage. Then I reconnected my custom ecu and it started but the engine idled very rough. After leaving it running for a few minutes, the car seemed to run better and I could drive it back home with the new ECU/TCU connected!! Accelerated better then ever and I've drives fine. Took it to 100 but no CEL yet. Obviously OBD1 is less fussy so I'll probably not get the P0453 and P0450 (Fuel pressure related system emission code). I've yet to see if I'll get the misfires on all 4 cylinders on the highway (usually above 120km).

There is a strange thing, however. Just before I switched to the new ECU, used a continuity tester to check the connections on the bypass from the OBD1 dizzy to the crank. I'm not sure it's right, but there is a red/green and blue/white wire for TDC and CYP sensors that need to be address so apparently fellow who did the swap had to extend 4 wires from the dizzy to the connecter in the crank (since there's not Cranks sensor in the OBD1 F22b jdm).

The connections are as follows:

RED to GREEN/YELLOW
GREEN TO BLACK/WHITE
BLUE TO GREEN/YELLOW alson
WHITE NOT FOUND

How was my car running this way, I can't understand???? I'm pretty sure that those wires are not connected properly. THe yellow/green and black yellow (on the 2 pin plug) are not even carrying tdc or Cyp signals from the dizzy.

What's more strange is that my car won't start unless that plug is connected???? I thought with OBD1 ECU the signals from the Crank are not even read on my OBD2b harness??? Can someone help.

The car is running fine, just idles a bit funny (shakes a bit but not as with the OBD2 ecu), but I think it's probably related to spark plug/wires/or the IAC idle Screw (that I've been messing with).

Will post if I get any CELS.

also, I think I also have the OBD2a harness not OBD2b (otherwise following your pinout would have not worked); See below there is a big difference btw the obd2a and obd2b:


OBD2a OBD2b Function OBD1 Color Notes
A01 B05 Injector 4 A02 Yellow
A02 B04 Injector 3 A05 Light Blue
A03 B03 Injector 2 A03 Red
A04 B11 Injector 1 A01 Brown
A05 A08 SO2H No connection on OBD1
A06 C01 PO2H A06 Orange/black
A08 B12 VTS A04 Orange/White
A09 B20 LG1 A26 Black/Red
A10 B02 PG1 A23 Black
A11 B01 IGP1 A25 Yellow/Black
A12 B23 IACV A09 Green/White
A15 A06 PCS A20 Red
A16 A16 FLR A07 Green/Yellow
A17 A17 ACC A15 Black/Red
A18 A18 MIL A13 Green/Orange
A19 A02 ALTC A16 White/Yellow No connection on D16Y8 P2Nb
A20 B13 ICM A21 Red/Green
A22 B22 LG2 B02 Brown
A23 B10 PG2 A24 Black
A24 B09 ICP2 B01 Yellow Black
A27 A20 FANC A12 Yellow/Green
C01 C31 CKFP No connection on OBD1
C02 C08 CKPP B15 Blue/Green
C03 C20 TDCP B13 Orange/Blue
C04 C29 CYPP B11 Orange
C05 A27 ACS B05 Blue/Red
C06 A24 STS B09 Blue/White
C07 A10 SCS D04 Brown
C10 B21 VBU D01 White/Blue
C11 C22 CKFM No connection on OBD1
C12 C09 CKPM B16 Blue/Yellow
C13 C21 TDCM B14 White/Blue
C14 C30 CYPM B12 White
C15 C10 VTM D06 Orange/Green Connected to VTS on OBD2a
C16 A26 PSW B08 Brown/Red
C17 C05 ALTF D09 Pink No connection on D16Y8 P2Nb
C18 C23 VSS B10 Yellow/Blue
D01 C27 TPS D11 Pink/Black
D02 C26 ECT D13 Red/White
D03 C17 MAP D17 Pink/White
D04 C19 VCC1 D19 Yellow/Green
D05 A32 BKSM D02 Greem/White
D06 C03 KS D03 Red/Green No connection on P08, P28
D07 C16 PO2S D14 White
D08 C25 IAT D15
D10 C28 VCC2 D20 Yellow/White
D11 C18 SG2 D22 Green/White
D12 C07 SG1 D21 Green/Blue
D14 A23 SO2S No connection on OBD1
D16 A30 EL D10 Green/Red No connection on D16Y8 P2Nb


Thanks

Bird333

I don't know about the JDM engine, but in OBD2 the two sensors that are normally down by the crank are inside the dizzy on an OBD1 engine. So you will have to connect those wires that go to the crank to the proper wires that go to the dizzy. In any case you should be throwing CELs for those missing sensors.

despat

I'm not throwing any CELs. The car is running perfectly and giving me much better mileage. I tried to connect to scanner using the OBD2 port and got nothing under integra or accord. Is there another way to read the CELS. I've not got a check engine light but there could be a hidden CELL thats not showing.

Bird333

There should be a 2-pin plug that you can jumper and then count the flashes of the CEL light to get any codes. Something else to consider is that there maybe some differences between an Accord engine harness and an Odyssey harness. You really need to get a pinout for a 97 Odyssey and compare to the spreadsheet.

DVSRMZ450

Hello..ok i bought a jdm f22b sohc vtec to replace with my f22b2 in my 96 accord lx auto...i was told that i had to change out the oil pumps because of the crank postion sensor in the 96 n up accords, so i had the pumps changed, i also bought the correct ecu that i have to use, but im havin trouble finding out what distributor to use. I bought a 96 accord ex distributor but the plug dont match the engine harness out of my old motor because it has an external coil and the one i bought has an internal coil...so my question is do i need an accord ex engine harness? Is there anything else im missing to complete this engine swap? I want to keep everything obd2