Differences in wiring harnesses (Manual vs Auto, DX, LX, and EX)

[Chaseph]

Wondering about the difference in wiring harness between auto and manual and among different trim levels. I have a 93 EX 5 speed that leaked an insane amount of oil, so last year I bought a JDM H22A from HMO. After reading through the H22 swap sticky a bunch of times I finally got it in. But in the process I messed up my original wiring harness. There was a bit of confusion about which harness to use... Anyway , I ended up having to go to the junkyard and take a harness off of a 90 or 91 wagon that was either an f22a1 or a4 and was also an auto. So here's the issue, 2 of the 3 chassis plugs on each side fit, one on either side doesn't. I assume for the extra sensors involved with the auto trans. My question is if there's any difference aside the extra plugs for the auto and if I should just cut the plugs and solder the matching wires and leave the others assuming the for the auto trans or did they possibly route things differently?

[Raf99]

Wondering about the difference in wiring harness between auto and manual and among different trim levels. I have a 93 EX 5 speed that leaked an insane amount of oil, so last year I bought a JDM H22A from HMO. After reading through the H22 swap sticky a bunch of times I finally got it in. But in the process I messed up my original wiring harness. There was a bit of confusion about which harness to use... Anyway , I ended up having to go to the junkyard and take a harness off of a 90 or 91 wagon that was either an f22a1 or a4 and was also an auto. So here's the issue, 2 of the 3 chassis plugs on each side fit, one on either side doesn't. I assume for the extra sensors involved with the auto trans. My question is if there's any difference aside the extra plugs for the auto and if I should just cut the plugs and solder the matching wires and leave the others assuming the for the auto trans or did they possibly route things differently?

I can tell you that the harnesses are different. The main ones route the same way and have added wires for accessories. IE: Power folding mirrors you need to add wires to the harness/connectors.

[Chaseph]

So you think I should just cut the chassis plugs and solder the wires that match and leave the ones that are presumably for the auto trans sensors? I could also salvage the chassis plugs from my original 5 speed harness and leave the extra wires off and solder both sides of the original plugs? I also noticed after taking notes about wire colors to different important sensors that some wire colors are shared. For example I found a blue/yellow wire on the distributor and also one on one of my extra plugs for the auto trans. So I wanted to make sure I can just connect the matching wires and assume I'm not missing anything actually important

Thanks for the reply!

[Raf99]

So your three options here are:

1. Get pins and wires and add wires to the harness / connectors. = doing it the right way !

2. Soldering wires to the points you need to which gets messy

3. Getting OEM harnesses to replace what is there, but this is almost impossible as you have to take the car apart

[Chaseph]

See the problem is that the new auto harness has extra wires and therefore needs bigger chassis plugs. So I ended up reusing my original chassis plugs and soldered the matching wires from the auto harness (in the car) to the chassis plugs on the manual harness. But now my problem is that there are 2 wires from the original manual trans harness that don't have a match to the automatic trans harness on the plug that fits.. also the O2 sensor plugs are reversed on the harnesses. Both male or both female, not sure which. But they line up together and don't match, so I can't get it to fire up until I get the O2 sensor from the automatic trans junkyard car. then I'll know if those extra wires need a home or not. And if they used different colors for the unmatched wires or if they routed some things to different plugs on the chassis side of the harness

[Raf99]

See the problem is that the new auto harness has extra wires and therefore needs bigger chassis plugs. So I ended up reusing my original chassis plugs and soldered the matching wires from the auto harness (in the car) to the chassis plugs on the manual harness. But now my problem is that there are 2 wires from the original manual trans harness that don't have a match to the automatic trans harness on the plug that fits.. also the O2 sensor plugs are reversed on the harnesses. Both male or both female, not sure which. But they line up together and don't match, so I can't get it to fire up until I get the O2 sensor from the automatic trans junkyard car. then I'll know if those extra wires need a home or not. And if they used different colors for the unmatched wires or if they routed some things to different plugs on the chassis side of the harness

Ya, now you're seeing why it's easier to just get the harness plug you want. Now your only option is to swap the whole harness or just use the connector and un-pin and re-pin all the wires.
As for color codes and what goes where, you need a manual with a wiring schematic to tell you what is what / goes where.

[Chaseph]

So you don't think this automatic harness will work? I still have to do my VTEC wiring (already have the ECU pinned for it) so couldn't I just get it started and see what I'm missing then rewire it from the computer like all the VTEC related wiring? Otherwise the junkyard I pulled my new harness from had a 5-speed Accord there too, but it was buried much further into to the weeds so I just figured the auto wagon harness would work just as well being all the cars used the same, or almost the same, engine and the wiring would route the same way. I'm not afraid the re-pin the ECU if I need to, already did it for VTEC but wanted to re-do those wires I ran

[Grumpys93]

If the harness isn’t too hard to pull, I believe it would save you more time and frustration to simply pull the manual harness. That way if you run into problems later on you don’t have to chase wires to verify you didn’t pin a wire in the wrong spot.

[Chaseph]

No I'm sure it wouldn't be, especially since I've just pulled the harness from an accord twice in very recent history lol. But honestly I just tried to fire it up yesterday and she wanted to start. O2 wiring isn't together because the plugs don't match although they're both the same 4 wire sensor.. both plugs were male, or both were female.. not sure which but they're the same, but just flipped in either harness. So I think I'm gonna take that O2 sensor and try starting and see if it throws a lot of codes and what they are. If it's bad I'll go get that other harness. It doesn't look like those 2 accords have seen much action lately. Thank you guys for the help!