Hey yall. I’m doing a automatic to manual transmission conversion and I thought while I was at it I might as well switch the harnesses too but after getting the manual harness put in I realized the distributor plugs are different along with a plug that I have no clue where it goes. The harness is from a 1998 Honda dx d16y7 while the car it is going into is a 1999 Honda lx d16y7. Here are some photos of what I’m confused on.

Overview difference

Wire colors

Wandering wire

Color of wires

 

You cannot use a '96-98 Civic engine harness of ANY KIND in a '99-00 Civic. You MUST use a '99-00 Civic engine harness. It is not necessary to swap a manual engine harness into the auto chassis, although doing so will be a cleaner install since you will not see all of the unused plugs dangling over the transmission. Alternatively, you can repurpose some of the auto transmission wires for things like VTEC and not have to run new wires because they already exist inside the harness bundle... and you can always cut off all extra plugs and terminate (cap) all unused wires and then tape over them to clean things up a bit.

 

Yeah did some more research and realized they switched from obd2a to obd2b which in then wouldn’t allow the 98 harness to work on the 99 with that I have a follow up question would a y8 harness would or are the wiring different other than the vtec obviously.

 

Modifying the engine harness that originally corresponds/matches the chassis is always the best policy because all wiring that joins at the crossover plug (green plug under dash near the ECU that connects to the engine harness) is matching and sorting this junction out is the most challenging for those who are not comfortable with wiring... wires between the ECU plugs and engine sensor plugs can easily be pinned out. Some say that a Y8 engine harness will work just fine in a Y7 chassis (assuming you are using a '99-00 type harness in this case), but I cannot confirm this is entirely true. When you plug in the green plug of the Y8 engine harness into your Y7 chassis, you will see that a whole bunch of wires do not match up between both sides of this plug. This may be immaterial for engine function, but there may be side effects with respect to other chassis function.

 

So the automatic harness would work but would the harness plug to a 99 manual ecu the same or would I need to do repinning

 

The manual ECU will plug into the automatic engine harness... you will have ONE extra ECU plug on the auto harness that will NOT plug into the ECU (this will be the far right one on the ECU as you look at it from the plug end).

 

Thanks for the help I also have one more question when looking for an ecu I’ve been told multiple could work for my car but I don’t wanna purchase and then be money down so would the ecu code 37820-p2e-a11 and 37820-p2e-a12 both be compatible or no.

 

The "P2E" version denotes programming for the D16Y8 engine... which is correct for you. The trouble is going to be the last three digits, which is the version identifier. I am not sure what years the "A11" and "A12" versions correlate to, but if you look at the ECU plug end facing you (plug lock slots facing up), the proper ECU version will have pins in the first three ECU plug slots from left to right... and the fourth slot (all the way to the right) will be empty. If you are buying this ECU online, or from a distance from you that requires shipping, I suggest you request a close up photo of the ECU plug end so you can identify it.

 

A little irrelevant to the post but I’m out of luck so here’s this I finally finished the transmission swap and it went pretty smooth but I got sold a bad transmission so now I have to buy a new one I was wondering if you knew any credible suppliers where I could buy one from or would that be something I would have to find out on my own. Any help is appreciated thank you.