Should hud speedo work without engine/ecu/engin harness

[Sentra91ser]

Hello everyone,

I have a strange question to ask about the digital speedo in the s13. The original speedo did not work when I bought the car. I then pulled the engine/trans, ecu, and engine harness out of the car, sold them, and started preparing for a sr20 in the future.

By chance I came across a "working" cluster. I went to test this cluster in the car and only a few things light up. Is this simply because it communicates with the ecu and/or the other components that are missing? Or should the speedo still light up? Interior lights, head lights, sunroof, and many other components still work, so I just assumed I could test the digital speedo with the other things missing.

I tried searching, but this is kind of an odd scenario to find.

[biggie]

Probably would need everything hooked up to test properly.