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Hacking up Honda's ECU
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PostPosted: Fri Aug 26, 2005 5:23 pm 
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First off my disclaimer (gotta have one right ;)). I, nor anyone else is responsible (except you) if you screw up your car, house, life or anything else using this information. USE THIS AT YOUR OWN RISK. Now that’s out of the way, let’s proceed.

I (like maybe some of you out there) wanted to turbo my Accord (still haven’t turboed it yet. One day, one day). As I began to research the idea, I discovered this thing called ‘engine management’. There are various ways to do this, but what seemed to be the safest and relatively cheap was ‘chipping’ a Honda ecu. Well of course I discovered that there was practically no freeware development for an Accord, it was all about Civics and Integras. Also, I discovered that it was all about MANUAL trannies and OBD1 cars. Luck would have it that I would have an automatic tranny and an OBD2 car. So, I thought ‘well I’ll just get an OBD2>OBD1 conversion harness and all will be well’, but soon found out that these harnesses were designed for manual cars and I couldn’t find automatic pinout info for any of these cars. I also found out that OBD1 Accords had a separate tranny computer which further complicated matters. So I was forced to create my own custom OBD2>OBD1 conversion harness that would work with a tranny computer (TCU). So I bought an automatic P06 (Civic) ecu and converted it to a P28 since this seemed to be a popular freeware platform. As I continued to research, I discovered that Civics didn’t use a separate tcu so this purchase was a mistake. I thought all was lost. I needed an OBD1 ecu that had freeware development that also controlled a separate tcu. Thankfully, I discovered that Integras used such an ecu. This article is the culmination of about 2 years (off and on Thanks to the family. ;)) of research and fabrication.

Ok, this article deals with creating an automatic OBD2a>OBD1 conversion harness and the parts necessary to run an auto OBD2a Accord on an auto OBD1 ecu. You ODB1 guys can also use this info to switch out your Accord ecu for a more ‘freeware friendly’ Integra ecu. Unless you specifically use the parts I did, you may not be successful. All parts discussed here will be USDM parts. I used a P75 auto ecu, a tcu from a '94-'95 non-vtec Accord (F22B2) and my engine harness was an OBD2a harness. My car is a 1996 Accord LX sedan.

Parts needed:
1. An Automatic OBD2a>OBD1 conversion harness
2. An AUTOMATIC P75 (94-95 Integra) ecu. (The code on the ecu should look like *****-P75-x5*. The ‘5’ in the last section of the code lets you know it is an automatic ecu. The ‘x’ should be an ‘A’ (US 49 state) or ‘L’ (California))
3. A tcu for your engine block. (In my case a F22B2)
4. A ROM from an AUTOMATIC Integra ecu. (I used the USDM OBD1 ‘332’ rom from http://www.pgmfi.org/twiki/bin/view/Library/EcuDefinitionCodes)
5. ECU fuel and ignition maps for your engine that will work in the above rom/bin.
6. Some type of bin editor like Uberdata or Crome.
7. Service manuals for the ecu, tcu and OBD2 engine harness you have. In my case, I needed a ‘94-‘95 Integra manual, a ’94-’95 Accord manual, and a ’96 Accord manual.
8. The necessary parts and equipment to chip your ecu.
9. A chip burner.

NOTES: You may be able to use a manual P75 bin as they may actually be the same code and only behave differently based on the hardware configuration of the circuitboard. If someone wants to test this, please do. You could buy an auto OBD2>OBD1 conversion harness from a dealer, BUT you will need to check to be sure that all the wires match up to the equipment you will be using. Automatic OBD1 ecus and tcus from different cars have slightly different pinouts.

Ok, for people who want to create their own custom harness, here is a parts list:

1. Somewhere in the neighborhood of 100-120 feet of 20 gauge wire.
2. About 10-20’ feet of 18 gauge wire. (Maybe 16 gauge)
3. Wire strippers
4. Crimpers (I got part WM9999-ND at Digikey)
5. 65 contact receptacles (small pins) Tyco part # 175061-1 (-2 is gold if you want them)
6. 26 contact receptacles (big pins) Tyco part # 173631-1 (-2 gold)
7. 2 x 26-pin OBD1 plugs (Tyco part # 174516-6)
8. 2 x 22-pin OBD1 plugs (Tyco part # 174515-6)
9. 1 x 16-pin OBD1 plug (Tyco part # 174514-6)
10. 1 x 104-pin OBD2a pin connector (Tyco part # 179686-6)
11. Soldering equipment (i.e. soldering iron and solder)
12. Digital multimeter.
13. Optional, heat shrink tubing

You can call Tyco and ask for samples of the above parts if you can’t get them from junk ecus and harnesses. They will limit the quantity you can have. DO NOT ABUSE THIS. Get only what you need. Also, try to get a few extra pins just in case you mess up. Here is the conversion table for creating your harness. NOTE: For OBD1 tcu A9 I connected this to the 'Tachometer test wire under the hood. You maybe able to get this signal from OBD2 A20 but I couldn't verify it. If someone could confirm that would make the install even cleaner. Also the headings are a little off I don't know how to line them up in this post. If someone could tell me how I would appreciate it. Just shift the 2nd, 3rd, and 4th headings over to the left some to postion them over the correct columns.


Code:
Conversion Table for Accord Automatics                              
Differences in Accord ECU and P75                              
                                       
1997 OBD2 Accord   1994 Accord TCU pins   1994 Accord ECU pinouts   P75/P72 Pinouts   NOTES                  
                                       
A01            A02      A02      Injector 4               
A02            A05      A05      Injector 3               
A03            A03      A03      Injector 2               
A04            A01      A01      Injector 1               
A05            NOT CONNECTED   NOT CONNECTED                  
A06            A11      A06      O2 Heater               
A08            A04      A04      VTS Vtec Sol            
A09            A26      A26      LG1               
A10            A23      A23      PG1               
A11      A23                  On Tcu called 'Ignition Input'         
A11            A25      A25      IGP1               
A12            A09      A09      IACV               
A13            A10      NOT CONNECTED   MCS (Engine Mount Control Solenoid)      
A15            A20      A20      Evap Purge Control            
A16            A07      A07      FLR               
A17      A22      A15      A15      A/C Clutch relay            
A18            A13      A13      MIL               
A19            A16      A16      ALT C               
A20            A21      A21      ICM               
A20?      A09               DO NOT connect this to OBD2 A20.  Splice into Tach test wire.   
A22      A25                  On TCU called 'Ground'            
A22            B02      B02      LG2               
A23           A26                  On TCU called 'Ground'            
A23                      A24           A24      PG2               
A24      A24                  On Tcu called 'Ignition Input'         
A24            B01      B01      IGP2               
A27            A12      A12      FANC               
A28            NOT CONNECTED   NOT CONNECTED                  
A29            NOT CONNECTED   NOT CONNECTED                  
B03      A05                  Shift Control Solenoid 'A'         
B04      A04                  Lock Up Control Solenoid 'B'         
B05      A06                  Lock Up Control Solenoid 'A'         
B08      A15                  ATP D3               
B11      A03                  Shift Control Solenoid 'B'         
B12      A18                  Shift Interlock            
B13      A08                  D4 INDICATOR            
B14      D12                  Mainshaft speed sensor ground         
B15      D19                  Mainshaft speed sensor         
B16      A21                  ATP Reverse            
B17      A13                  ATP 2               
B18      A11                  ATP 1               
B22      D15                  Countershaft speed sensor ground         
B23      D17                  Countershaft speed sensor         
B24      A17                  ATP D4               
B25      A19   B07      B07      ATP PN             
C02            B15      B15      CKP P               
C03            B13      B13      TDC P               
C04            B11      B11      CYP P               
C05            B05      B05      A/C SWITCH            
C06            B09      B09      STS               
C07      D06   D04      D04      SCS               
C08            D07      D07      K-Line, Data Link            
C10      A20                  On TCU called 'Battery Input'         
C10            D01      D01      VBU (ECU power I think)         
C12            B16      B16      CKP M               
C13            B14      B14      TDC M               
C14            B12      B12      CYP M               
C15            D06      D06      Vtec pressure switch   There is no connection for a OBD2 Accord.  I.E. there is no connection on OBD2 C15
C16            B08      B08      PSP Switch               
C17            D09      D09      ALT F               
C18      D09   B10        B10      VSS               
C20            NOT CONNECTED   NOT CONNECTED                  
D01      D07   D11       D11      TPS               
D02      D05   D13       D13      ECT               
D03            D17      D17      MAP               
D04            D19      D19      VCC1               
D05      D02                  Brake Switch Input            
D05            D02      D02      Brake Switch            
D06                  NOT CONNECTED   Knock sensor not connected s/b D3 on other ecu's   
D07            D14      D14      O2 sensor               
D08            D15      D15      IAT               
D09            D12      NOT CONNECTED   Exhaust gas recirc. Don't see this for P72/P75. Possibly on D12
D10            D20      D20      VCC2               
D11            D22      D22      SG2               
D12            D21      D21      SG1               
D13            NOT CONNECTED   NOT CONNECTED   SECONDARY O2 Sensor Ground         
D14            NOT CONNECTED   NOT CONNECTED   SECONDARY O2 Sensor         
D15            NOT CONNECTED   NOT CONNECTED   FUEL TANK PRESSURE SENSOR      
D16            D10      D10      Electrical Load Detector         
      A10                  NOT NEEDED            
      D03      D05      D08      BARO OUT   This seems to be D5 on a P06/P28 ecu with Integra bin.
      D11      B04      B04      AFSB               
      D13      B03      B03      AFSA               
      D16      A18      A19      FAS               
      D18      D18      D16      VREF               



The OBD2a connector will be at right angles so you will have to bend/cut them straight.
Now what I did was measure and cut all my wires first and crimped the pins on them before anything else. There will be two parts on each pin to crimp. On the outer end, the crimp should dig into the insulation of the wire. In the middle of the pin, that crimp should go around bare wire. The bare wire should NOT go up inside the socket of the pin. So strip your wires accordingly. If you arrange your ecu and tcu like I did (see pics here about halfway down the page); you will need approx. these wire lengths:

47 pieces of 4-5” wire (you could shorter if you wanted, but it would probably make it hard to work with) these are the wires that will go from the OBD2a connector to the OBD1 ecu plugs.

27 pieces of 21” wire (these go from the ODB2a connector to the OBD1 tcu plugs.)

5 pieces of 19” wire (These go from the OBD1 ecu plugs to the OBD1 tcu plugs. They will have pins at both ends.)

Take note of which OBD1 pin number the pins will go in. The larger openings will use the larger wire and bigger pins. IMPORTANT: This is how you count OBD1 pins. Looking from the side that the wires go in (wire side) with the clip at the top; pin 1 will be the first pin from the left on the top row. Pin 2 will be below it (i.e. first pin from the left on the bottom row.

For example:
1357……
2468……

IMPORTANT: Counting OBD2 pins is different. Looking from the pin (side opposite the soldering leads) with the clip receptacle at the top, you count across and then go down to the next row.

For example:
12345
678910

On the OBD1 ‘A’ plug pins 1,2,3,4,5,6 and 23,24,25,26 are the bigger holes. On the OBD1 ‘D’ plug pins 1,2 and 19,20,21,22 are the bigger holes. OBD1 ‘B’ plug all holes are small.

A good method I found for soldering my wires to the OBD2 connector was to wrap the wire around a large paper clip in a spiral and then slide the wire over the lead. This helps hold the wire on the lead since most of us don’t have 3 hands. Then just solder the wire to the lead making sure solder gets all around the wire/lead. Try not to heat the lead up too long (no more than 3-4 seconds) or you could melt the plastic that it’s held in. If the lead does get loose try to even it up inside the connector with a similar pin and use a little superglue around the base of it. Be sure you don’t cover the pin with superglue or it won’t have continuity. If you do cover it, just scrap the pin with a sharp knife or something to get the dried glue off.

Once you got all the wires soldered to the OBD2 connector. You will probably want to slide some heat shrink tubing over them down to the base to prevent any shorts. Once I had them all in place, I used a hair dryer to heat them up so they would shrink to the wires. Now it is time to insert the wires into the OBD1 plugs. The wires go in the plugs with the ‘crimp’ side facing up toward the clip. Be careful putting them in the correct locations. They are practically impossible to get back out. You should hear/feel a slight ‘click’ when you have gotten it in all the way. NOTE: You might have to ‘reshape’ the outer crimp a little if you squeezed too flat so it can get in the plug holes. However, be sure the outer crimp is still gripping the wire’s insulation after you reshape it.

Once you got your conversion harness together, it is a good idea to check each pin for continuity with your multimeter.

Now all you need to do is ‘chip’ your ecu. I won’t explain how to do that here. There is plenty of info on how to do that. Finally, take the Integra bin and copy the fuel and ignition maps for your engine into it. Be sure to disable vtec if you don’t have it. Then burn your bin on a chip and install in your ecu. If you did everything right; your car should start with no CELs.


I would like to thank AD, tallh22a, Superorb, Andrew and everyone at Pgmfi.org.

Attached is the conversion spreadsheet sorted by OBD2, OBD1 ecu and OBD1 tcu, and the Integra bin I used.


Attachments:
Auto OBD convert info and Integra bin.zip [37.92 KiB]
Downloaded 616 times


Last edited by Bird333 on Fri Oct 14, 2005 12:18 pm, edited 5 times in total.
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PostPosted: Fri Aug 26, 2005 11:47 pm 
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I have added this to the Wiki under Conversions, it's availible here:

http://www.pgmfi.org/twiki/bin/view/Lib ... oOBD2-OBD1

Look it over and make sure everything is right, especially the table.


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PostPosted: Sat Aug 27, 2005 1:55 am 
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I have edited the table a little to get rid of the some of the words like 'power', 'ground', and 'g114' that were throwing the columns off. Otherwise the table looks good if those changes can be made. The only other thing was where I discussed how to count ecu pins. I had the numbers on two different rows to illustrate the differences between OBD1 and OBD2.

Thanks!


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PostPosted: Sat Aug 27, 2005 3:32 am 
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that's a lot of good work. thanks for sharing.


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PostPosted: Sat Aug 27, 2005 7:01 pm 
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I updated the table and the pin counting. I didn't notice the pin counting, as in the edit screen it looks ok, then it puts it all on one line in the wiki. Let me know if I missed anything in the table, there's a lot of stuff in there. :P


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PostPosted: Sun Aug 28, 2005 1:22 am 
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The line references I will use will be the OBD2 pin numbers since that is the order the table is in.

1. Line A20 (the second 'A20') remove 'ICM' and 'A09' s/b under the Accord TCU column not the ECU column.

2. First line A23, 'A26' s/b in the TCU column not the ECU column.

3. Line A27, nothing s/b in the TCU column. Accord ECU column should have 'A12' and P75 ecu column should have 'A12' in it and 'FANC' should be in the 'Notes' column. Basically, just shift those three to the right one column.

I think that is all.


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PostPosted: Sun Aug 28, 2005 3:10 am 
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Got it. That third one I should have caught when formatting the table anyway, duh. :)


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PostPosted: Thu Oct 13, 2005 5:35 pm 
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Can someone make this small change to the wiki article.

Change this line:

I used a P75 auto ecu, a tcu from I believe a 1995 vtec Accord (F22B1) and my engine harness was an OBD2a harness.

To this:

I used a P75 auto ecu, a tcu from a '94-'95 non-vtec Accord (F22B2) and my engine harness was an OBD2a harness.

I also highlighted the change in red in my first post (it doesn't need to be red in the wiki).

Thanks


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PostPosted: Thu Oct 13, 2005 6:26 pm 
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Done. :D


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PostPosted: Tue Jan 17, 2006 12:50 pm 
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Could someone please make this small change to this line in the wiki article?

From this:
2. An AUTOMATIC P75 (94-95 Integra) ecu. (The code on the ecu should look like ****-P75-x5.

To this: (just add an '*' after the '5')

2. An AUTOMATIC P75 (94-95 Integra) ecu. (The code on the ecu should look like ****-P75-x5*.

Thanks!


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PostPosted: Sun Dec 27, 2009 11:31 pm 
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Edit: Never mind to what I said here before, I got it figured out. I'm gonna add some info in here too, just to give some more reference material for others to work off of.

All my info is for a POB('96 Accord LX) ECU, P75('94-'95 Integra GS or LS) ECU, and a '94-'95 Accord LX/DX TCM.


http://www.mediafire.com/?4y2tumzutuk <--Spreadsheet w/ a lot of info

http://www.mediafire.com/?ozomljgwy4j <--Wordpad Document; bare bones info


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PostPosted: Tue Mar 09, 2010 11:46 pm 
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Hi,
I read one of your posts and got a feeling that you're the guy I'm looking for to solve my Oddy 97 swap problem. To summurize, I've replace the original engine with a JDM F22b (accord OBD1, non-vtec, automatic) engine. The way it's been done is I used an OBD1 dizzy and ran the wires from the dizzy to the (red, green, blue, white wires) on the crank since the Harness and ECU are still Original (obd2).

this is how it's connected:

to solder the OBD2 connector to the OBD1 dizzy:

connector------------ dizzy
green-----------------green
yellow/green---------yellow/green
black------------------white
yellow-----------------orange


then there's gonna be 4 more wires comin off the OBD1 dizzy, which get extended down to the TDC and CKP on the oil pump (again, i cut the bottom connector off and soldered them):

OBD1 dizzy------- OBD2 TDC & CKP:
blue/green----------blue
blue/yellow --------white
orange/blue--------green
white/blue----------red

Problem is the car idles horribly and also does not start right away (chugs a few secs before starting). Even worse, I'm getting random misfires on all cylinders and ECU light flashes when above 120km per hour. Other then that the car runs fine on highway and gives 12km per liter on highway.

I've checked every other problem that could be, so please don't waste your time asking me about the other parts. My mechanic who did the swap says that the problem is my ECU. So i got an similar

Accord EX Auto non-vtec 2.2liter ECU and nothing changed (proving that he was wrong to say that my ECU was bad).

Then I purchased an Accord 95 (xxx-POB-xx) non-VTEC Auto ECU and a conversion harness but car won't start.

So now I'm thinking that the only way is to covert the engine to OBD2 by replacing all these from a USDM post 96 Accord OBD2 engine:

*Oil pump
*Crankshaft Position Sensor
*Crankshaft Timing Gear (OBD2 one has 12 pins on it)
*Crankshaft Pulley (harmonic balancer pulleY)

Is this my only way around the problem? Or do I still have a way to chip the ECU as explained in your article?

viewtopic.php?f=54&p=119274

I'm not sure the your article applies to my but if it does, can you please explain to me what I would need to do this. I've already got a red conversion harness (that's often sold as for manual cars only).

Your help would be greatly appreciated.

Thank you!


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PostPosted: Thu Apr 01, 2010 12:49 am 
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Bird333 wrote:


Now all you need to do is ‘chip’ your ecu. I won’t explain how to do that here. There is plenty of info on how to do that. Finally, take the Integra bin and copy the fuel and ignition maps for your engine into it. Be sure to disable vtec if you don’t have it. Then burn your bin on a chip and install in your ecu. If you did everything right; your car should start with no CELs.


I would like to thank AD, tallh22a, Superorb, Andrew and everyone at Pgmfi.org.

Attached is the conversion spreadsheet sorted by OBD2, OBD1 ecu and OBD1 tcu, and the Integra bin I used.


I found your instructions and was wondering if i could do this for an automatic 97 honda Oddy with JDM 94-95 Obd1 2.2L non-vtec, Automatic, Accord engine. I'll be using the original OBD2a harness and and

If i understand right, I need a to chip the p75 ECU with the ignition maps of a 94 Accord 2.2 non-Vtec Auto bin. Is this findable on ebay?

Sorry but I have no idea about chipping. Is the equipment for chipping found on eBay (or elsewhere) for an affordable price. I'm in canada btw. Any help would be appreciated.

Thank you!


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