Re:obd0-obd1 harness
 

Yes.. 90-91 PM6s are the same as far as internals..

88-91 PM6s are the same as far as the wiring harness that goes to them.

PR4 is also the same wiring harness (minus the PA sensor.. don't worry about it).

P75 is OBD1, so obviously has a different pinout.

Pin-outs for all of these standards (OBD's) are all over Honda-Tech.

Re:obd0-obd1 harness
 

90 pm6 is the same. The right side of that conversion guide where it lists all the pin numbers is a pm6 pinout, you can reference that with your accord pinout, most of the major stuff is labeled so it should give you an idea if its the same or not. The left is a standard obd1 that will work with any p06 p28 p30 p74 p75 etc. The number in parenthesis is the actual honda pin number using the normal zig zag pattern of counting the pins, the number before that not in parenthesis is just counting left to right which he put because it is a little simpler but its not the same system everyone else uses, its all explained in their if you read it but just remember if you are cross referencing it with any other pinout use the numbers in parenthesis. Honda did not change to obd1 until 92 on the civics and tegs so my guess is you will need a 92 or 93 f22 distributor for obd 1, 90-91 may work if you stay obd0.

Re:obd0-obd1 harness
 

Some PR4s have internal PA...some external. I don't know if I would say "don't worry about it"

Re:obd0-obd1 harness
 

Isn't that solved with code? PM6 (internal) vs PM7 (external)?

Re:obd0-obd1 harness
 

What is the PA sensor, and what does it being internal or external mean? Could you please explain?

Re:obd0-obd1 harness
 

PA sensor = PAIN in the ASS sensor

Re:obd0-obd1 harness
 

Ha, ha. Actually, that doesn't help me much. Since I'm gonna be doing this for the first time, they will probably all be PA sensors :).