Hello, I've recently started to rebuild my 91 vert. It's a roller I found in a New Mexico barn. It has no engine, transmission, or wiring harness, but it's straight, rust free, and only cost $350.

Now that I'm digging into it and prepping for an engine, I'd like to test out some of the electronics. So my questions is:

Is it possible to rebuild the battery wiring to the ecu and body to test body and cabin accessories? If yes, do I need an engine harness or can I start from scratch?

I'll note that I have the original ecu, but I will be going with a stand-alone ecu (likely Haltech) to get it running.

Any help or information offered is appreciated!

 

Good work finding a clean shell!
There are many ways to approach this. If the wire to the interior is in place it is black and is close to about 8awg. It will be on the driver side. From the factory, this is not fused? from the battery. I would add 12vdc to the wire and a fuse just in the event of a short or ohm test the wire to ground. Add a temporary ground, at least 8awg to the firewall.

With the key turned or otherwise hot wired, you should have power to at least some of the interior and hopefully no smoke. If you have wiring experience, I would ohm out every wire from the fuse block back and check for shorts or hope there are to many cut wires.

Just as a heads up, while researching grounding I found a great article from the head engineer from Haletech. He recommends a very specific grounding scheme for cars with sensor grounds that ground through the engine vs. sensor grounds that do not ground through the engine. This includes proper grounding for the new ECU as well. Star grounding is a bit confusing at first and also understanding ground offset. Once you got it, it is hard to forget.

Without the aftermarket ecu standard FC3 grounding still needs some small upgrades.

To directly answer your question, having to make a custom harness is highly likely. Stock grounds are with the engine harness.... I think? Besides the firewall to transmission one, of which, with the aftermarket ECU, it is a big no, no according to Haletech.

Someone else here will have good recommendations so, take this with a grain of salt. This is just what I would do.