B18C1 (OBD1) into 98 Civic EX help! (Variables at play)

[98b16a2]

Hi,
I have a couple different things at play that is causing me some confusion as to where to start.
I currently have a 98 Civic EX that was an automatic I know the most common response of many will be to dump the body, and get a manual. I however am mid-way through converting it to manual. So, with that in mind, I know the factory car is an OBD2 vehicle, with the automatic wiring harness in it.

I have a rebuilt B18C1 that's OBD1 with a manual transmission. I have the ECU that came with the engine as well.

I've read a couple different "How to" guides on doing a swap, all of which are generalized for an already manual car which mine is not. So to get to the point in which I can use those guides is where I need advice.

I assume I can't keep the 98 Civic EX auto ECU. So do I swap in the OBD1 ECU from the GSR integra, and replace the wiring from the ECU all the way from the fuse box out? Or do I purchase the 96-00 manual EX wiring harness, utilizing the same ECU, and make the adaptations to the harness to fit the B18C1?

Appreciate any help that's offered (that isn't negative of course)

 

[serrilion]

You could get an OBD2-OBD1 adpter off Rewire or something that would allow you to keep your stock wiring harness and use the Motor and ECU... Also going from auto to 5 speed sucks, but if you have the motor and trans from the B18c1 it shouldn't mater all that much, just make sure u wire up the reverse wire other wise no lights, and also deal with the ignition and the jumper so you can start your car as it will need to think its in park lmao

 

[Dual-500]

^ in addtion to above, get wiring schematics for BOTH cars. You will want to study them.

I'm thinking once wiring is converted to the OBD1 ECU with the correct adaptor(s) it should work. Should not have a "look for park" to start issue - but, no guarantee there. Actually, it might and probably will have a look for park issue now that I think about it a bit more. That (start in park) could be done a myriad of ways (from factory) and may not be limited to the ECU, in fact it probably isn't. It will probably require jumping a wire or two together in the start circuit. Oh yeah, the start in park circuit will probably just need to be moved over to the "Depress clutch" circuit that the car doesn't currently have. Shouldn't be a big deal.

Hence, the need for schematics. You should be able to find them via Google search - that's how I found the OBD0 & OBD1 schematics when I did my '91 hatchback.

Also, you will want a decent ohm meter and leads and some alligator clip leads to use when testing harness's and you harness work.

When I did the schematics, I made a "Shop Copy" using Adobe that printed them across many pages. About 10 pages as I recall, then cut the edge margins off, overlayed them to align the wires and taped them together to make one large page. That really helps. Also printed copies of the pin to pin list of wires.

With the large copies of the wiring schematics you can make notes, use colored highlighters to trace circuiits and such. When doing the work. Locate wires on schematics, then confirm with the meter from the ECU to wherever it goes before chopping things up. Always solder connections and use heat shrink tubing. When finished, the harness should look like a factory job.

Have a look at post #5 on the link for some how to wiring suggestions:

https://hondaswap.com/auto-multi-media/zc-dohc-1991-hatchback-transplant-epilog-515235/

 

[98b16a2]

Thank you both for your responses. I think from what I've gathered is this. And correct me if you see a flaw in my rough plan.

1. Utilize the B18C1 ECU.
2. Purchase OBD1/OBD2 adapter harness.
3. Purchase the manual 96-98 Civic EX wire harness.
4. Alter the the 96-98 wire harness accordingly, to accommodate for the new B18C1 swap.
5. Perform the remaining changes to the wiring to account for the manual conversion.

Does that sound like a logical approach to the situation? I rather not buy un-needed items as those can add up quickly if you don't go about things smart =p

I'm still trying to determine if the automatic wire harness thats natively in the automatic ex can be used. Some say yes, some say no. The noted thing to do is simply cut off the extra plugs that the auto harness has, and "you'll be fine". Not sure on that. Opinions welcome on that one =p

 

[Dual-500]

Also, get the wiring schematics for the model that supports the B18C1 version that you are installing. You will want both sets of wiring schematics.

I can't see a reason why the existing car wiring can't be modified to accept the swap with manual tranny.

 

[98b16a2]

Alright. When I get home from work, I'll have to pull up the schematic on the automatic vs. the manual wiring of the 98 EX to see what the differences are.

 

[Dual-500]

Without looking, I would guess a wire to lock up the torque converter clutch, and the park switch. Could be electronically shifted - there's a few more wires. All that can be capped off and essentially abandoned with the exception of the park circuit which will become the clutch pedal circuit.

 

[Dual-500]

Alright. When I get home from work, I'll have to pull up the schematic on the automatic vs. the manual wiring of the 98 EX to see what the differences are.

Yes - keep in mind you are overlaying the older wiring and manual tranny onto the existing wiring. It's not a huge effort, but could give you fits if not approached systematically.

I can't stress the importance of electrically identifying the wires with an ohm meter before changing anything. Don't just look at schematics and find colors. This isn't a paint by color adventure. Not being sarcastic. But, errors are made is shop manuals, and changes in wiring harness's and such. There is no 100% guarantee the wire colors in the car matches what's in the book.

That's just a friendly caution. I'll also add, my experience with Honda wiring, not vast by any means, but still I have some hands on with Hondas and many years with other types of wiring to include aircraft - Honda wiring harness's and connectors are very high quality. They are well made and very reliable.

Chances are you will walk through this without any issues as you are taking the right approach. If you run into issues, you will have the tech data at hand to resolve them.

Using the meter to identify the circuits you are working on will confirm what you are doing, but will also give you familiarity with the circuits and locations, pins, etc. That will be priceless if you encounter problems and have to troubleshoot. When I did the swap on the hatch, it took 3 days of troubleshooting and swapping ECU, distributor, etc only to find the ground lug on the engine by the thermostat was loose - I forgot to tighten it up. That caused the ECU to remain dormant when ignition was turned on - it didn't power up. When I figured out the CEL should have came on with ignition, the first side of wiring I checked out was the power side of the ECU, then finally the ground side and it cranked right up.

 

[98b16a2]

So far everything on conversion is going great.
As far as I can tell, the 5-speed conversion went great. Linkage is in place, feels good. The wiring appears to be correct. However I wont be able to get a definitive answer until I start the engine up. Which I'm working on.

The question that is probably the least technical of all, considering all that I've done, is this. How is the wiring harness ran, behind the engine? Does it go in the "cavern" where the IAB solenoid is hiding? Or does it go below the intake completely, just above the rear engine mount? Or....does it attach to the firewall? I've been trying to plug wires in based on the orientation of the harness, and depending where I have it, changes what I need to lengthen...etc.

I've been googling the hell out of 96-2K civic with the b18 swap, and I can't find a single pictures that clearly tells me what way to run it.

Any help would be appreciated.

 

[Dual-500]

It runs along the back side of the engine, below the intake manifold - hits oil pressure sensor, temp sensor switch for radiator fans and alternator.