I was about to buy a 96-98 -> 99-00 conversion harness from Katman when he mailed me this. Can I have some corroboration? Most everyone told me that I would need to get a new ecu or harness to make the swap work. Please read...
"Ok, if you do get the 99+ Si coupe engine harness, you won't have to buy an ecu jumper from me....since the Si engine harness runs all the way down to the ecu box itself, and will plug n' play to the Si ecu.. All of hte 96+ civic's have this type of engine harness, where the harness runs all the way down to the actual ecu; and doesn't break off at the shock tower like on previous year civics or 90-01 integras. You won't even have to wire up VTEC if you do wind up using the Si engine harness, since VTEC wiring is already embedded in that particular harness.." - Katman (who if this is true is apparently a nice guy)

I am confused, and I don't want to keep bothering him if I am not going to buy anything from him.

Situation: 97 dx chassis. 2000 si swap + wiring harness + 2ksi ecu. Need a conversion harness, or not?

Once again thanks for all your help.

(yes this is a duplicate post)




[Modified by Ehron, 7:37 PM 10/9/2002]

 

No, you don't need to add any wiring. It's plug and play.

IF you want to use an OBD1 ECU, then you'll still need a harness convertor.

 

the 99-00 si harness will NOT plug directly into the 96-98 car harness.

You will be doing alot of rewiring to get it to work right but its possible. Might be easier to get a harness adapter and modify your stock wiring harness to adapt to the si engine. Basicly the si has 4 plugs going to the ecu and the dx/lx/ex 97 has 3 plugs.

 

Use your stock harness and add the necessary wires. Then find an OBD2 P30 or convert to obd1 and run a chipped p28. You need an ecu from 96-98, the 99-00 have different plugs. I'm sure the interior harness is pinned differently as well from 96-98 and 99-00.

I used a 96 Del sol vtec ecu and it was plug and play into my 96 ex harness. The only wiring mod I had to was put the d16 CKF plug onto the b16a2, took about 3 minutes.

If you want to use a Si harness and ecu, your going to be doing it the long way. You can sell your Si harness and ecu and buy a p30 w/ the money.

 

If you want to put a 2000 Honda Civic Si engine and ECU in your 1997 Honda Civic you will need to get a '96-'98 OBD2 to '99-'00 OBD2 conversion harness (OBD2v1 to OBD2v2).

The reason for this stems from the fact that the engine harnesses are slightly different between the '96-'98 Civics and the '99-'00 Civics.

The '96-'96 Civic engine harnesses have all of the necessary ECU plugs on the engine harness (3 plugs on manual ECUs and 4 plugs on automatic ECUs).

The '99-'00 Civic engine harnesses do not have ECU plug 'A' on the engine harness. It is included in the cabin harness.

In addition to this the '96-'98 Civics and the '99-'00 Civics ECU wiring is arranged differently (different wires in different locations) even though the ECU plugs are the same pieces.

This is a fact. I know this from experience.

-kenji


[Modified by kenji, 11:57 AM 10/9/2002]

 

Yeah I have been looking for a delsol vtec ecu to no avail. I have to pass emissions so I cannot revert back to obd1. They don't sniff tail pipes for my chassis; they use the onboard data aquisition unit.

I thought I would have to modify something, but Katman said I did not have to... I am so confused now.

 

if you need to pass emissions, just plug your dx ecu back in.

 

Now that is not very helpful...

 

I was in the same boat as you dude. And I will elaborate a little more about why the 99-00SI or EX harnesses will not work in a 96-98 civic.

Not only are the plugs different (which can easily be corrected with a conversion harness, but the number of ECU plugs on the engine harness are different.

The 99-00 SI engine harness has only 2 ECU plugs on it. The 3rd ECU plug comes from the Cabin harness.

The 96-98 engine harness has all 3 engine harness plugs on it.

There is also another plug(green) on both 96-98 and 99-00 harness's that plug into the cabin harness.

So in order to make a 99-00 SI harness work in a 96-98 chassis, two things are possible, and both options aren't worth the time. First, you can change every signle harness in the dash, change the climate control, the heaterbox and the blowermotor. I actually know someone who did this too. Or you can try to make up the 3rd ecu plug from the wires you have in the car. This is the most time consuming and tedious process, and there is room for lots of error.

I looked into making the 3rd ecu plug, since I had a Helms on hand and am very good at wiring and reading schematics. I wont get into how much trouble it was going to be.

So what did I do?

I got a 96-98EX harness and spent about a half day extending plugs. I also made my own coversion harness to use a 00 ITR ECU. But having the immobilizer removed from the ECU screwed up the check engine light system. Long story short, I just use a JDM ITR ecu now.

You should be ok to use the SI ecu, since I don't believe it has an immobilizer in it.

So, use your stock harness and add/extend plugs/wires. Get the conversion adapter from Katman to adapt a 99-00 ECU to a 96-98 harness and you will be golden.

 

if you can't find a p30, get the 96-98 -> 99-00 convertor and plug in the p2t

 

Thanks Tony. I guess I need to learn to solder? I have a Helms as well, but I have never undertaken such a project. Do I need to solder to extend those wires? Thanks.

 

You dont need to solder per say, you can use butt splices.

Both those have a tendency to corrode with moiseture soooo..

YES YOU HAVE TO SOLDER. And use heat shrink on the solder joints.

 

All caps. Good to see you are back to normal. Thanks for the info.