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CRX ECODiesel Ram
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Discussion Starter #1
I am starting to see electrical bugs pop up with my 27 year old car and harnesses. I had to recently make a distributor subharness to go direct from the distributor to the ecu due to a persistent code 9 (3 distributors, multiple ecus as well). I like the idea of what Rywire and others do, but i have more time than money have decent electrical experience (the most fun was wiring an auto d16a6 up to run in a 1978 civic wagon on stock computer and with only tying into the original harness for power).

Has anyone made their own engine harness that runs directly to the ecu for an obd0 car? if so how did it work for you? Any big pitfalls?

I would start with whatever obd2 civic harness I can get a hold of, split it up and do a wire by wire repin to obd1 plugs. solder and heatshrink as needed, rewrap with new loom and new tape. remove what I do not need. I would be repinning for obd1 ecu, distributor, alternator, i already have obd2 injectors and obd2 IAT, of course im still using the obd0 coolant temp sensor, so that would either be plugged and a new thermo housing sourced or just rewire that as well. It appears as if I only really need about 6 or 7 wires to tie into the chassis harness, and not only would i bypass all the aged wiring I could clean stuff up a lot and I could get rid of the obd0-obd1 jumper which i jsut dont trust that much either.
 

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CRX ECODiesel Ram
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Discussion Starter #2
It looks as if i can still get a brand new automatic civic ex harness for $200 at the dealer!
 

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Brokedick Millionaire
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OBD-1 harness with Rywire harness....what Beav had to do on a 84-87 CRX with OBD-0 wiring harness that was cracked and broken.
 

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Premium Member
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You could get one of theses custom harness from me and not use a 96-00 civic harness that most likely will be the same as your 27 year old harness. All wires,pins,seals and the ecu plugs are brand new. Only thing I reuse is the sensor housing plugs.
 

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Love the Civic
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2Jz has the setups, I wouldn't go anywhere else, unless I am doing it myself......trust me pony up for his.
 

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CRX ECODiesel Ram
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Discussion Starter #7
the 96-00 civic harness i planned on using is factory new....nothing at all like my 27 year old harness...$191 for brand new and then I can get to work on it.

That is a very good looking harness, but I do not have a core harness since the one that I have on the car helps me get it started to get to and from work every day, I cannot part with it for more than a day or two....

Rywire is $450 plus shipping, wireworx 460, chase bays is not even under consideration. Oem is 191 plus cost of new ecu plugs/pins, and my time...which I have more time than money. Figuring that since I have wired a 78 civic to run an a6 with auto trans and fuel injection, and then later wired up a track only crx from scratch this will be easier since its starting with clean and fresh wiring.
 

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What year and model is the chassis?
 

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CRX ECODiesel Ram
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Discussion Starter #9
I have a 1989 honda crx si running obd1 distributor, obd2 iat in the intake tube, and obd2 injectors, and the map sensor was originally firewall mounted but is now on the tb. running the distributor on a separate subharness made from 96-97 civic parts, and the o2 sensor is a conglomeration of an obd0-1 jumper, a plx wideband and my own wired up plugs. only thing that has ever been an issue was distributor sensor signal on the factory harness as well as cracking insulation and corroded copper...
 

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CRX ECODiesel Ram
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Discussion Starter #10
I have received the brand new harness from Honda. I depinned all obd2a connectors, marked each wire that I am keeping. I stripped the automatic transmission wiring out of the harness, the evap purge, the power steering switch as well as the vtec wiring. I need to change the 3 wire iacv to a 2 wire plug, and need to change the plug on the distributor. I placed an order with Mouser electronics for puns, obd1 plugs and and milspec heat shrink tubing. once the new plugs are pinned I will repin the driver side firewall plug and then figure out where to splice in the power, ground, vss, fuel pump and ac controls from the ecu.

In addition I also ordered 2 cap sets to restore a pair of ecus to make sure that my ecu or its plugs are not a source of problems. Hoping to have it all finished next week sometime. At the same time I am installing the new Exedy sport clutch and opening my trans to see whats wrong with it, i rebuilt the original transmission yesterday. Once I have solid wiring I am hoping to get some real tuning on the dyno (before i spend more money on my new dodge ecodiesel truck...).
 

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Send those extra harness bits to 2JZ, he will love you long time.


if you have any issues talk to him. He did a fantastic job on my custom OBD2A chassis/OBD1 ecu pluggable harness for my future manual swap and turbo build
 

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CRX ECODiesel Ram
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Discussion Starter #12
we have bounced a few pms though he has not been on for a few days i guess.
not that I am thinking i will have trouble but having pointers on pitfalls or perhaps ways to do it easier is always nice.

it always looks a lot harder when you look at the whole harness but it gets easier when you look at one wire at a time. i have not chunked anything out yet just leaving it all in a pile so if he or someone else wants a bunch of stock wires with plugs i can send em!
 

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Discussion Starter #13
B connector is finished, and now working on the driver side plug. It appears that i am going to pull many of those wires to the driver side to make life easier.
I am actually down to a SINGLE wire that I am not sure where it is going. will try and post a few pics tomorrow.
 

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Discussion Starter #14


I am not going to claim its ANYWHERE near what 2JZ, rywire or others can make, but its my work, its almost all brand new wiring, lots of freshly crimped connectors, fresh shrink tubing, fresh tape all based on a factory new harness.
Test fitting it is satisfactory for me, i am able to eliminate all but one shock tower plug, and then run the harness direct to the obd1 p06 s300 I use. I am very likely to pick up an Hamotorsports refurbished ecu as well, all 3 of my spares have issues. One has a cap that leaked and damaged the board, the other has a bad fuel injector circuit, the last has bad traces from a crappy socket job. My current ecu seems good...but its still over 20 years old. I am going to re wire the PLX wideband for a cleaner install as well.

I also pulled my manifold off, and will add a thermal gasket and mild port matching on the manifold side. The intake mani has a 62mm opening and I am using a 60mm tb, so i may replace that while it is out. I see some fuel lines I am not happy with that will be replaced as well.

Also the transmission is coming out for repair...might break down and get a a PIC 4.5 FD to go with my M factory lsd...if I do that i might go ahead and get koni yellows, have my new bumper painted AND get a new windshield!

Also putting in calipers from an accord wagon along with 10 inch rotors on the front end.


all this cause of my wire harness and continuing electrical/management issues...
 

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CRX ECODiesel Ram
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Discussion Starter #16
I ran all stock wires...its all brand new honda oem straight from the dealer wiring. Only thing being changed is connectors and what its wrapped in.
 

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Classic Man
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Nice man, looks good. We bought some new harnesses for customers recently too, they arent expensive at all! And it always impresses people to see a brand new looking harness.
 

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When will anyone make cabin harnesses for Hondas?

These things along with my 240, have so many breaks and weak connections.

Seems like more and more problems I experience are from old as hell cabin harnesses screwing up power to the main relay, ignition
 

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Discussion Starter #19
Honestly I am already thinking long term of how I can re-wire the car, at 27-28 years old 320k miles and all of them in Texas heat I figure a lot is getting funky in the harness.
 

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Discussion Starter #20
It is complete, in and runs. It is NOT as pretty as stuff from Rywire or 2jz...but it works and I did it myself. I still need to re set up the plx and wideband, but that it just power, ground and the o2 input to the ecu. And remounting the gauge. The harness is not really trucked but fits a lot more hidden than prior. I am happy enough with it....

Sadly in the process of either rebuilding my trans, installing my clutch and re-opening the transmission to install the Mfactory LSD something went wrong, as long as my clutch is disengaged everything sounds normal. Once I engage the clutch it gets noisy as hell, rattling metal on metal sounds that are NOT healthy. In gear it engages just fine, rolls forward or back just fine (brakes need to be bled so nothing more than a roll) and the noise changes tone but remains nice and loud...taking a break and yanking the transmission and if the clutch looks great I am sending it out to a pro to build...
 
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