DIY OBD-1 Conversion Harness

[2drSE-i]

So I've been slowly collecting parts to do my conversion harness. This is going to be a slow, painstaking process because I don't really have half of the parts, or much time to get to the junkyard, but here are the parts i do have.

Burt up PJ0 ECU
Pigtails for said ECU
20 AWG Wire
Soldering Iron
Solder
Desoldering Bulb

Here are the parts i still need
Pigtails for OBD-1 ECU



Heres what i've done so far



First, you want to start by dismantling a spare accord ECU. After removing all the screws, your left with the circuit board.

Next is the fun part. You need to desolder all of the pins out of the circuit board, to remove the connector.

Now you may begin soldering on extension wires.


I've only got the one soldered on there because I had an epiphany, which caused me to realize that i should PROBABLY use shielded wire if i didnt want a bunch of interference and a faulty ECU connection. I'll keep this updated.

[AccordB20A]

good work man, ive always thought it has been easier to make my own one, funny enough todays the day im installing my OBD1 swap in my accord, anyways ill post a pic to show people what it looks like when done, all i have to do is figure out what the HELL error code 11 is
http://www.youtube.com/watch?v=aRDQtnBAYLk problem solved, its the idle mixture ajustment screw thing



I destroyed the donor ecu to get the plugs out instead of de soldering them it was easier haha

[A18A]

i cut mine off with a knife lol

[LX-incredible]

So I've been slowly collecting parts to do my conversion harness. This is going to be a slow, painstaking process because I don't really have half of the parts, or much time to get to the junkyard, but here are the parts i do have.

Burt up PJ0 ECU
Pigtails for said ECU
20 AWG Wire
Soldering Iron
Solder
Desoldering Bulb

Here are the parts i still need
Pigtails for OBD-1 ECU



Heres what i've done so far



First, you want to start by dismantling a spare accord ECU. After removing all the screws, your left with the circuit board.

Next is the fun part. You need to desolder all of the pins out of the circuit board, to remove the connector.

Now you may begin soldering on extension wires.


I've only got the one soldered on there because I had an epiphany, which caused me to realize that i should PROBABLY use shielded wire if i didnt want a bunch of interference and a faulty ECU connection. I'll keep this updated.

Or you could just buy one from me. lol.

Don't worry with the shielded wire for the jumper. As long as you keep the wire lengths short (I've gone over 12" without issues), you'll be fine. It's the long runs you want shielded, as they'll pick up interference from running alongside the ICM wire and such for damn near 10 feet. The only shielded wires you need to add to a fuel injected accord are for the CKP sensor. I run a new shielded o2 wire in my add on harnesses to eliminate the need to tear into the stock wiring. You can use the stock o2 wire and just add the ground, +12 V switched from the main relay or ign (any yel/blk, blk/yel on the harness), and the heating element from A6 (obd1 connector).

Nothing on the obd0 A connector or obd1 A connector is shielded so go ahead and practice with that first. Solder the wires straight, don't wrap them around the pins. It makes a mess, the pins don't get enough temp for a good bond, and you will loose valuable space that is desperately needed on the obd0 B and C connectors. Only 3-5 new wires get soldered to the obd0 connectors, all others will be directly off of the obd1 connectors; So cut them long!!! The 90-93 accords obd1 ecu connectors are going to have the the wire colors closest to the ECU pinouts you find online.

Remove any pins or wires that wont be used before soldering. Obd1 can be removed by pulling the backstop out with a pair of needlenose pliers and a push pin or icepick. Obd0 pins can just be broken off. I recommend shortening the longer pins, scraping, and tinning everything. It's what I do and will greatly improve the durability of the joint.

Use heat shrinks, not electrical tape! The pins are copper, so they'll withstand quite a bit of flexing. Shrinks will help to distribute this if installed properly. Single pins (not next to other wires) are the weakest and may need their wires secured to the bundle.

Here is a pic of the jumper I sold to messy. It gives an idea what needs to be removed, added, and the work that's involved:



That's all I can think of for now... except don't inhale that shit. It'll fuck you up after about 50 joints. lol.

[2drSE-i]

Wow, thanks for all the input. I was initially worried about the shielded wire, so thanks for clearing that up. I was pretty worried about twisting the wire around the pins and running out of space, thanks for telling me that. Heat shrink was a MUST for me, i have a big roll of electrical tape sitting there because i soldered my cell phone charger back together (damn cats chewed it up...)

I did plan on cutting the wires long on the obd1 pigtail. From the looks of things you didnt extend the wires at all. That thing looks NICE. What is the bunch of wires up the middle? The new wires, like the o2 sensor, distributor wires, etc?

[stat1K]

those are the shielded wires to run for the obd1 distributor.

[2drSE-i]

those are the shielded wires to run for the obd1 distributor.

I guess he said that if i could READ!!

[stat1K]

oh i didn't read what he wrote i just assumed.

[ShyBoyCA6]

nice i have a my old ecu i wont be needing but wanna do something like this to it

[LX-incredible]

Yeah, those are the added wires. With a little practice and patience you can remove and solder your new wires directly to the obd1 terminals. If you have a good double-crimper, you can also buy the AMP terminals at www.ballengermotorsports.com. They also sell the sumitomo terminals and seals for the stuff under the hood.

A small torch will allow you to remove all the pins from the board at once, without all the stress thats put on them when removed individually.

[2drSE-i]

I've noticed practice really helps with this process. All i have is a 30 watt soldering iron and a desoldering bulb. Trying (and i say trying because it WOULDN"T work for me) to desolder those pins was a bitch. I wound up dremeling them out.

Forgive my ignorance, whats an amp terminal?

[LX-incredible]

AMP is a company that manufactures connectors. The obd1 ecu connectors you're using are AMP.

[2drSE-i]

As you can see (maybe, if the picture isn't too small) i took your advice. I haven't really been working on this the last week or so, I only got half of the A connector put together. It wasn't TOO close together, but I'm gonna have to figure out a better way to hold the wire to the pin on the B connector.

My new favorite tool doin' work!


Me, using my combination of ghetto fabbed tools, old ECU pigtails and a circuit tester. (Not that I'm unsure of my work, but i just want to make DAMN sure)

Oh and i don't know what assclown started the rumor that you can heatshrink using a hair dryer, but they LIED. I just got my 100' roll of 3/32" heatshrink today (thank you ebay) So now i need to come up with a heat gun. I will probably worry about that more once i get all of the wires soldered on.

[A18A]

you can use a lighter, just run it along the heat shrink. don't hold the lighter in one spot, and it will shrink nice and evenly

[LX-incredible]

Put your hand over the back of the hair drier to increase heat. I usually use a old space heater and get them all at once.

You might just be practicing with your soldering, but it will be easier, quicker, and more reliable if you solder the obd1 wires directly to the obd0 connectors. I try to keep the amount of splices to a minimum, and rarely use butt connectors.

[2drSE-i]

Yay update.

New parts

If you can't tell what those are, they are obd1 ecu pigtails and 92 accord distributor connectors and pigtails.

and i took your advice lx-incredible, went back to the starting point.



working on my conversion chart again. Waiting to hear back from LX-Incredible on my pinout.

[2drSE-i]

OOK update. Asked (harrassed) LX-incredible for some pointers (a lot...) and being the kind guy he is, obliged.

(My dog watching me tear apart my car to find a mystical A/C issue......turned out to be a fuse.....)
Anywho, heres where i got tonight

And if you look carefully in the background you can see why i had to do a few pins 3-4 times.

How in the hell do you guys get the wires to stay put on the pins? I'm having a hell of a time...

[A18A]

i clamped the plug to my desk with vice grips, then added solder to the wire, or the pin, or both, and then solder them together

[LX-incredible]

How in the hell do you guys get the wires to stay put on the pins? I'm having a hell of a time...

100 watt soldering iron and burnt fingers. Tinning the pins and wires helps a lot.

[2drSE-i]

100 watt soldering iron and burnt fingers. Tinning the pins and wires helps a lot.

Yes it does....Half of the C connector last night took 3 hours, the entire B connector tonight took 1. The practice helped too I'm sure, but I'm happy with the progress. Heres my pic of tonights progress



Again man, thanks for all your help. Seriously though, If anyone is thinking of doing this for themselves..........its a HUGE pain.


Day 1: Removing old connectors from ECU, Getting them prepped 2 hours
Day 2: Getting OBD1 connectors, stripping them, getting them prepped. 4 hours (Including the trip to the junkyard)
Day 3: R&D, Pinout charts, headaches, etc etc etc: another 3 hours
Day 4&5: C connector. 5 hours
Day 6: B connector. 1.5 hours
Day 7: A connector. ~1 hour (They are much bigger pins, I'm shooting for 1/2 an hour)

All in all, ACTUALLY working on this project has been a week long in my spare time, around 16 hours and that does not even include the new distributor wires, o2 wires, brake switch wire or service connectors. Save yourself the time and spend 300 bucks on one of his. He stands behind his work 100% and is a hell of a guy.

[2drSE-i]

Was gonna wait till after work today to do this, but decided to do it before

took me 45 mins while browsing 3geez LOL



It doesnt look nearly as pretty as LX-incredible's (thanks, a 12th time for all your help), nor is it complete yet. All the soldering to the PJ0 connectors is done though, its all downhill from here!

[Civic Accord Honda]

yay!!, working on them harnesses is fun aye? only thing i hate is de-pining them... i distoryed a harness in my civic trying to get the pins out then someone wrote a how to on how to exactly get them out 2 days later ><

[2drSE-i]

yay!!, working on them harnesses is fun aye? only thing i hate is de-pining them... i distoryed a harness in my civic trying to get the pins out then someone wrote a how to on how to exactly get them out 2 days later ><

Depinning was pretty easy, once I read how to do it. I very seriously thought about depinning the whole harness so i could just solder everything up and then insert the pins when i was done, but decided it would be more effort than i would be saving.

[AccordB20A]

im going to re make mine too, seeing LX-incredible's one made mine look ugly as haha.

when i put a ZC into the CRX im going to OBD1 that also using a B20A dizzy and cam sensor