Long story short trying to kill two bird's with one stone and get me and another guy what we need. I need a 90-92 TPI (MAP) Manual harness (thanks squirrels) for a bird. He has a 91 TPI (MAP) Manual harness but is swapping to LSX.

I'm still waiting on a reply in the lsx forum if a new C100 connector can be purchased and the factory LSX harness just be pinned to the new C100 or if a factory 3rd gen harness has to be used to splice into the factory LSX harness.

I've been told that a TBI harness can be repinned for a TPI engine but there is also a difference if a TBI (MAF) harness is used vs a TBI (MAP) harness on what has to be changed.

If a new C100 connector can't just be pinned using the factory LSX harness I was thinking one of the 3 harness's I have laying in the garage could be used for his C100 wiring splice in for the factory LSX harness.

The three harness's I have:
1. 89 TBI not sure if MAF or MAP I didn't pull that much out of the box and also not sure if it is manual or auto
2. Unknown year TBI not sure if MAF or MAP again since I didn't follow the wiring out to see which connector it had and not sure if it is manual or auto either
3. A hacked TPI harness from unknown year and not sure if auto or manual either. The hacked section is no where near the C100 so this may be the best bet for him to use so we both end up with what we need.

I'm not sure off hand what the manual vs auto connector difference is since both cars here have T-56. I'm also not sure what the pinout difference is with converting a TBI harness to TPI and if it really matters if it is a MAF or MAP harness for and LSX swap.

So if anyone has direct information and experience it would be greatly appreciated. Looking through so many wiring posts it is all overwhelming and starting to mix together. Gotta love ADD!

 

Instead of rooting through posts, look for wiring diagrams.
Once you have everything next to each other visually, and see how many circuits are the same, you can see what is different.

TBI can be repinned for TPI.
TBI was not MAF in third gens.
If you need a C100, use the one from your bad TPI harness.

 

Can all TBI harness's be repinned as TPI though are some years more of a PITA then others?

That would make sense on the MAF I don't know why I didn't even think of that. Air cleaners for TBI cars sit right on top the TB so where the hell would a MAF sensor sit. I've only had one MAF car and it was an 87 with a 2.8 so I'm not very familiar with them and I've been away from the f-body scene for quite some time so I've become very rusty. I'll say it was probably back when LS1 swaps were just becoming a new thing. Yea it's been that long.

My thoughts though on the whole C100 bit. Since with and LSX swap you would use the LSX engine harness which means nothing that a stock 3rd gen harness connects to will be used other then the bulkhead connector in the firewall can't the bulkhead on the LSX harness just be cut off or the pins removed. Then reuse the pins (saying the pins are the same on an LSX harness) to pin out a new C100 vs splicing into a chopped off section of a factory 3rd gen harness.

I say this route since the C100 on the 3rd gen would have to be gone through anyway to meet it up with the lsx harness wiring. Can't the LSX harness just get pinned into a new C100 to match the bulkhead connector in the firewall?

Seems the later route would make more sense with just having diagrams for the stock bulkhead for the specific year car and the diagram for the LSX harness. This would also knock out the possibility of a poor solder joint or heat shrink gremlin down the line.

Unless of course the factory 3rd gen harness is still necessary to connect certain things under the hood which I don't know what there could possibly be with an LSX using completely different accessories and trans along with the fact of having it's own harness for anything that comes with it.

 

TBI is a MAP based system so it is easily repinned to run a MAP based TPI system. It can be pinned to run a MAF system but you will have to add in curcuits.

I don't understand what you are trying to ask....
If the LS uses the same pins then yes, you can just shove the pins in the appropriate sockets of the C100 connector. Otherwise you are stuck cutting and reconnecting a few wires from the C100. I believe that the only wires that need spliced are the ignition power, oil pressure, coolant temp, tach, torque conv clutch, coolant fans and fuel pump relay. The whole C100 does not need rewired.
http://www.austinthirdgen.org/mkport..._1990_C100.gif