Hello all, 
I'm a new comer here and I've also just started to learn about cars; please bear with me if I say and ask some obvious things aha. Before I move onto physical error eliminations I just wanted to ask around. So the issues with my Mr2 Sw20 current are, my Speedo no longer works, my ABS light is constantly on and my engine bay fan light is also constantly on. All of these issues, didn't exist before I tampered with my rear lights. I had a rear light conversion from NA to Turbo however I kept the NA centre piece, as a result my reverse lights didn't have a place to go. Thus I joined the reverse lights with the inner two section of the tail lights (I believe they're the ones that come on with the head lights). However, after leaving my friend's house after doing it, the issues stated above occurred. 

I have read around the internet with these issues, I understand that there are fixes to all this, however I just wasn't sure if this was caused by me tampering with the rear lights. Because I fail to believe that all THREE issues can happen at the exact same time. Could the joining of the lights perhaps damaged some fuses? 

Thanks in advance to all for any recommendations and answers.  

Welcome. I'd try disconnecting the reverse light wiring and see if that helps.

I'm thinking you also went from gen2 squarish lights to the more round gen 3?

Yea, I'm thinking about disconnecting the reverse lights tomorrow and seeing how it goes. I just can't wrap my head around how it possibly could've done all that. Also yea, I went from the squarish lights to the ground ones. Except I kept the centre garnish piece from the old set of lights.