(MS3X) Referencing N76 BOB, how do CPS and CAS connect from the harness side?
 

Background: 1990 car; 99 head and VICS IM; 97 block; MS3X and 99 Engine harness
Swap has not been done yet, just assembling MS right now while I collect parts.
Experience: noob, never touched a soldering iron before this

I've been reading through forum posts and gradually understanding how the ECU and pinouts and connections work, but one thread confused me (https://www.miataturbo.net/megasquir...-wiring-72473/). Specifically the part about connecting the CAS and CPS to 2H and 2J. How does the connection work if I'm not using the 12 pin connector on the N76 for the 99 ECU? I have a feeling the answer is in front of me, but I need another perspective. It's just something that I'm not seeing the right way.

I forgot to add, I'm swapping in the 99 harness, which doesn't use the 12 pin according to DIYAUTOTUNE hence the confusion

why are you using the 99 harness? why not just use your original harness? much less wiring to do. just need to swap the tps and iac connectors?

I figured it would work better with wiring in the nb trigger wheel sensor and VICS

is there a reason you want to run the crank/cam sensor setup and not just the CAS? It sounds like you are just making more work for yourself.

I was under the impression that I needed both of them. I don't mind extra work if it's worth it in terms of reliability or safety with timing.

You only need the CAS from your 1.6. You dont need to cam or crank sensor from the 99.

I think I understand that now. To add, after coming back to this board, I think I may be mixing up some of the pinouts as well, I'll attach a picture to show what I'm talking about, let me know if I've just been looking at this wrong

https://cimg9.ibsrv.net/gimg/www.mia...779a96e9ff.jpg

Could I have been taking this literally? The 12 pin on the N76 has 2L, 2J, 2H... etc, and the 16 pin for the connector diagram has 2L, 2J, 2H. Am i just getting this mixed up because the diagram was made for a 64 pin connector and my 76 pin just has the 12 squashed in?

If I'm right, I think I just needed to step back and look at things again from another angle. I think I answered my original question.

for one, you are using the wrong one. use the one i attached earlier. meant for you 1.6 harness. connector 2 is actually 4 on the BOB for the 1.6.

I would like to use the 1.8 harness because it's going to be a 1.8 car, there won't be anything left from the 1.6 in the engine bay, and I'm removing the 1.6 ecu. That's my reasoning for using the 1.8 harness.

I don't mean to come off as combative, this is just the setup that I want to run

Just seems like too much effort when you could just maintain the original harness for the car. When swapping to the 1.8 harness, you have to do a bunch of wiring to mate it to the chassis side. Been there and done that. From experience, run the 1.6 harness. change the IAC and TPS connectors, add the vics connector, extend the CAS wiring a little. just trying to help you simplify things here.

You've tried the harness swap before? Besides the chassis side adaptation, what was difficult about it? What sort of wiring is needed chassis side? For education purposes

the interface between the 1.8 and 1.6 harness is completely different. you would need to cut one connector off and then matchup the wires to the new connector. Are you good with wiring schematics?

For reference, i am currently running ms3x on my 93. On my stock engine i am just running it to a BOB using what i first posted. I am getting ready to swap a VVT engine in which i have to use the NB cam and crank sensors for. VVT relies on them. I am building an entire new engine harness because modifiying and making an NB harness would be a mess and pain.

You stated you are new to all this and have never soldered anything before. Make life easy for yourself and use the 1.6 harness. much less wiring to do that way.

So my understanding from your post is that the harnesses are essentially the same with the exception of the 1.6 needing the sensor swap and the VICS wiring addition? I appreciate your patience

Life is going to be easier, just ordered IAC, VICS and TPS connectors. I can see how I must have been frustrating you, I apologize. More reading, less posting.

I assumed you had the connectors since you had the harness. Keep us up to date.

why would you do this?