I am swapping from TBI to TPI and was wondering if I could just switch part of the connector that connects to the firewall on the driver’s side out. The connector appears to control headlights and turn signals. I have a picture to show what I am talking about. The circled part I wanted to remove and replace with my TBI part. Some of the pins are not the same in the connector though, it seems to have one extra row, so I am not sure if it would work.

 

That is the body half of the connector. It shouldn't have anything to do with the engine, or with the difference between TBI and TPI, as such. It will have something to do with whether the one car was a Camaro and the other a Firebird, or the year model, or something like that.

The other half of the connector is the engine harness, for things not related to the computer; such as gauges, ignition, alternator, starter, etc.

The only harness you should have to change is the other one, that goes through the pass side inner fender well to go inside the car and plug into the ECM.

 

Thanks for the reply. I just wanted to make sure, didn't want to have the engine ready to start then run into problems.

I have another question though. The harness I have does not have the connector for power steering. Is it possible that the car it came form did not have power steering? I looked at the connector that hooks to the ECM and their was no wire where the Hanes manual said the steering was. Can I just add a wire to the connector and run it to the plug for the power steering? Sorry if my questions are a little vague.

 

All that the power steering hookup does, is drop the A/C compressor when the steering prssure goes real high, and maybe bump the idle speed a bit. Typical adaptations for a weak motor. Probably not worth worrying about; I'm assuming of course that this won't be a weak motor.

The wiring is real modular. Basically there are 4 harnesses under the hood, plus options like cruise: the body harness; the "engine" harness, that hooks up the parts of the car that connect to the engine, such as gauges and batt supply and all that; the ECM harness, which is not part of the car as such, but rather part of the engine (comes from the engine plant on the engine, and just plugs into the car as it rolls down the line); and the A/C harness.

Go tour the Corvette plant in Bowling Green, or any other assembly plant that youhave access to. It is an experience that will teach you all sorts of things about how a car is put together, that you never even knew you didn't know. It will make you a far better car builder and engine swapper.

 

Thanks for all the help. Its going on the engine in the sig, I will try it without hooking it up. Seems like an easy fix if I need it. But I was surprised that the harness did not have the connection, it came from a 5.7L 91 camaro.

 

The TPI cars didn't use a power steering switch, at least not the 90-92 SD. Don't worry about it. Also, you can use either headlight/turn signal harness, they are the same except the z28 will have fog lights(pin C3 in that extra row). Good luck with the swap.