Okay so I have this friend who had a 97 civic, obd2a. He traded that chassis for a 2000 hatch and pulled his 97 engine harness and obd2a to obd1 jumper.

all the plugs fit into the obd2a jumper harness but the fuel pump won't prime and there is a left over ecu plug so the car has 4 ecu plugs. the pump will run if i jump the main relay pins 5 and 7. Why?

will he need to change the engine harness to a obd2b engine harness and get a obd2b to obd1 jumper harness?

i've found a few threads but all of them get off topic extremely quick so I apologize if this has been covered already but i read the ecu plugs are different yet they plug into the harness.

 

I would get a schematic and double check that the jumper is correct do you have a extra obd2a ecu he can use

I am using odb2a wiring from d16y8 and a obd2a gsr ecu on a b16a3 obd1 motor no problems

 

The jumper worked fine in the 97 chassis. Same problem with obd2a ECU

 

You need an obd2b engine harness, obd2b to obd1 jumper

 

^^^^

Second that answer.

 

That's what I figured. I just thought it was weird the car started if I jumped pin 5 & 7 on the main relay.

Why does this car have 4 ecu plugs in it? There is three that go to the ECU, a green one and another ECU plug similar to plug A that runs down the passenger side foot well towards the rear of the car. Or are there only 2 from the engine harness on OBD2B and the third goes towards the car?

Again, I assumed he knew what he was doing but this goes to show don't assume anything.

 

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okay i'm still confused a little here.

he went and picked up a 99 civic automatic engine harness and it, too, has 2 grey plugs, 1 blue and 1 green again adding up to 4 plugs. is one just not used in the case of the automatic transmission?

i can't find any info on automatic ecu's and harnesses. all diagrams are for m/t ecus. this **** is annoying.

 

yes, extra plug is for the a/t

 

Well, its your problem for not being detailed on this swap. Yes, you'll need an obd2b ecu to run this swap, or an obd2b to obd2a automatic conversion harness.

 

See 96-00 Civic service manual.

 

using obd2b to obd1 jumper and a p28 ecu with hondata s300.

i've gotten the correct harness for the chassis and plugged it all in. need to change some connectors over but that's the easy part.

and i finally got to page 364 of the service manual which says what the D connector is for.

tony - it's not my swap, he told me it just plugs and plays. not my fault he didn't research it and he keeps getting delayed. it is my fault for wasting time chasing wires that weren't needed to be chased though. my car was easy. i _researched_ what i needed to know. this kid throws a fit when **** doesn't work and doesn't know how to google or search this forum doesn't that seem pretty evident?

thank you, eghatch. simple question, simple answer. it's not entirely easy to find information about automatic harnesses when everyone doing swaps uses manuals wouldn't you say?

RonJ- i've been reading a lot of posts you've contributed to lately. i searched the manual and found the answer.

also i've found a typo on one of the guides. the picture is illustrated as connector b which is really c and connector c which is really b.

 

I didn't understand that last part.....what are you referring to.

 

on the bottom picture, B is actually C and C is actually B so you could try to understand where some identification issues may present themselves.




fixed.

 

Anybody that knows the difference between obd2a and obd2b knows this and we usually go hunt for other resources instead of one to confirm, or at least I do.

 

Well it's fixed for you so now other people, like the five other threads I've found, can have a more clear and concise answer, how about that? Little more friendly than saying search this look here when the thread titled "definitive swap thread" giving new to obd2 users correct information where it's advertised as true and correct. Let's be a little more friendly and open, or am I on the Nissan 350z forum?

Or are we going to further perpetuate and sponsor misinformation? Which is what we should be aiming to quash.

 

I would've assumed you knew the difference between obd2a and obd2b, since your friend used an obd2a engine harness and ecu in an obd2b car it would been notable that you'd end up with 2 A plugs.

 

No, I didn't. My cars are obd1 and a dc5 only swaps I've done was obd0 to obd1 Crx and dpfi to mpfi Crx. Everything else was similar engines in similar chassis.

 

how did you end up connecting plug A “chassis harness” to the p28?