drptop70ss

iTrader: (26)

I posted in engine swap for awhile, no luck there. Anyone have any helpful info? I am removing a 92 305 TPI engine and harness from a 92 trans am to transplant to another car, and I am hoping to find information on just what wiring from under the dash needs to be saved? Is there a pinout listing of the the wires on the connector that goes from under the dash to the ECM? The under dash harness looks to be one piece and I just dont know how much of it or what inputs to save to have the engine run. I am not using the steering column so I know I need a resistor for the VATS, and possibly the neutral safety switch is tied in so the computer knows if the car is in park, is that correct? Anyone have a pinout listing? Are there any other needed inputs from that harness or are most of the wires outputs to the guages and other parts? I am trying to do this with the factory stuff in place so I dont have to burn a new chip yet so as many factory parts will be left as needed.

drptop70ss

iTrader: (26)

Any help guys? Is there anything the ECM looks at besides the VATS on the underdash side of things? I have searched this site for days and I know there are people here well versed on TPI. However I see a lot of posts stating the TPI conversion info is out there but I sure cant find it.

Vader

You'll need all the underhood sensor inputs, and from inside the passenger compartment you'll need a neutral safety switch input, 4th gear switch input, ALDL connections, VSS input, cranking signal, and probably a few other things I'm overlooking. One thing you WON'T need is a VATS input. You can burn a PROM to eliminate that on a '92.

drptop70ss

iTrader: (26)

Thanks for the reply! I believe my VSS and 4th gear switch was on the engine compartment side of the harness so that should be ok. Isnt the cranking signal taken from the ignition module on the distributor? Just how are people selling standalone underhood harnesses when you need these things on the input side of the ECM? I have been reading up on the burning proms and such but want to try and run this without changing chips since I am leaving it stock at first just to try out the swap.

dyeager535

They sell standalone harnesses by eliminating things like VSS (which in my case was under dash) and "ganging up" all the power feeds.

On at least the earlier TPI setups, as a for instance, there are *2* injector fuses that would feed from the fuse panel. Not to mention ECM power, etc. On an aftermarket harness, all the power for the system will come from one source, like the battery. If they make a good setup, each circuit would be fused seperately like GM did, but since it's made to work "standalone" of a stock fuse panel, all the fuses etc should be contained within the new wiring harness.

I essentially did the same thing for mine, standalone, I pulled the power for everything from the stock fuse panel, but added another small fuse panel to feed each circuit seperately the way GM did originally.

In transplants, you will have to cut all of the stock power leads because they are hardwired into the fuse panel. If you are dealing with another vehicle that uses a similar GM fuse panel, you can take the cut leads, solder in a fuse holder on each plus one of the locking auxiallary connectors and plug them into the front of the fuse panel. That way is a bit more cluttered than getting power on one wire from the front of the fuse panel, and distributing it from a $6 fuse block.

drptop70ss

iTrader: (26)

The aux fuse panel sounds like a good idea, where did you buy it? This setup I am going to try in a 70 nova, and I want to try to use the nova wiring harnesses and just add the TPI setup to it, so I would pull power from the battery to the aux fuse panel and then distribute power from there to all the original fused power leads. I dont want to eliminate the VSS so I am going to keep that, and I am keeping everything else for now until I get the chip burning hardware. I want to do this cleanly and have everything work. I have been doing older car resto work for years, and have done troubleshooting on newer cars, but this is my first fuel injection retrofit into an older car. Thanks for the info!

dyeager535

500386 here is what I used.

That's WAY too expensive, you can get them on ebay for $4 plus if you look.

I like those because they can be mounted on an existing bolt which means you don't have to drill into the body if you don't want.

Only problem you are going to run into on the older vehicle is that some of the wiring needs ignition only 12V, and some needs batt 12V, so you will have to figure out how to get the switched power to whatever you want to run.

New stuff is easy, the stock fuse panels are set up with extras of the switched or batt terminals. Old stuff isn't.

drptop70ss

iTrader: (26)

Thanks, the extra fuse panel looks like a good idea, I will do some net searching for a better price. No problem on the power supply issue, there are IGN 12V and HOT 12v outputs on the older fuse box, I may just have to run one wire to a terminal block to supply multiple outputs. I think doing electrical is fun stuff so I am looking forward to digging into this. Thanks again for the help!