Wiring diagram variances-OBD 1 (91 vs 93) and OBD 2

3567 Views 4 Replies 3 Participants Last post by rallyser, Sep 20, 2013

rallyser

Discussion Starter · Sep 20, 2013 (Edited)

This will hopefully be a place for me to dump some new diagrams that I am creating that will hopefully help some folks out in the future. While I verify them and get my car running again, a few questions:

I am using the jumper wiring diagram from this post: PS this diagram needs to add the radiator high speed fan function OBD-I 10 to OBD-II 13
http://www.sr20-forum.com/information-library/28078-obd2-obd1-stepdown-harness-diagram.html

One problem I have noticed as I comb through multiple FSMs is there are a few differences within the OBD1 diagrams and I am wondering from folks who have gone before me if those are critical. For instance, according to the 1991 FSM, ECU pin 22 is a blue wire and connected to the crank angle sensor, while pin 23 is brown/yellow and connected to the consult port. In the 1993 OBD1 wiring diagram, that blue wire goes to pin 21 and pin 22 is a br/y wire to consult port. Is this a mistake in the FSM or will I need to change those pins in my ECU harness? I'm using the pdf downloads from nicoclub if you are interested to see them. ***SEE BELOW for mistake I found***
http://www.nicoclub.com/FSM/G20/

I have a 1993 harness that I am putting in my 1995 body. I have all the harness conversions done for the ECU harness to the body harnesses, save these last few questions. Then I'll be ready to run my Calum RT on my highport engine using the OBD1 harness.

Once I verify that the harness jumpers work correctly, I'll post diagrams. These will be for the plugs that are next to the ECU.

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ferrari21

· #2 · Sep 20, 2013

I recommend being more concerned about the location of a pin rather than the color of a wire. Often times when you are looking at an FSM, you're also looking at your ECU harness plug from and inverse position, and sometimes it is easy to confuse the number location of a pin itself.

Another thing to keep in mind, if your car was running correctly and no CELs prior to you swapping or changing any pins on the ECU plug, then it was probably correct.

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trbobrk

· #3 · Sep 20, 2013

I've been digging through FSMs a little bit in my spare time as I'm going to be doing an engine swap with an entirely different ECU, and probably and entire wire tuck at the same time to clean up the engine bay to make room for other things. There are a ton a wiring changes in the first few years. Basically every year is slightly different. 91, 92, 93, 93.5

There are some errors in the FSM though. It is like they made a change, and then when they updated the FSM, they went through to make the changes but they missed a couple edits because even within a single FSM they have conflicting info.

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rallyser

Discussion Starter · #4 · Sep 20, 2013 (Edited)

I am using my Calum RT, which ran my 1992 B13 rallycar without issues. I'll take out that FSM and wiring harness and make sure they correlate with the jumper and the converted harness I plan to run.

Just to pique interest, I've taken a 1993 auto harness and converted it to manual harness specs and plugs, including an electric speed sensor. It's taken a few days, but I can't find any OBD1 manual harnesses that aren't hacked or cracked up. I also figured that if folks want a how to, they can use this when they swap transmissions from auto to manual.

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rallyser

Discussion Starter · #5 · Sep 20, 2013 (Edited)

Just noticed something in the 93 wiring diagram on the foldout page!! MAJOR mistake in the numbering of pins. If you look at the sequence, they skip a white wire for pin 20 and just on to 21, but call it 20! That is why my numbers were off as I didn't notice that until just now. If I follow the pin sequence -1 from 20 on, then things are correct and my colors and pins line up correctly. If you know DNA, this is a frame shift mutation! AAARRRGGGHHH!!

Comparing the actual harnesses, not just the books, there are some wire color differences between 92 and 93, but the functions of those pins/wires is the same from 91-92-93 according to all the FSMs I have looked at.

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