Hey all,
so I've just finished installing controllers from my 91' to my 90' (speed controller and ABS controller) and it is all connected the way I found it in the 91' but the ABS light on the dash is illuminated when the car is turned on. I think I need to reset the ECU but I heard they have a learning curve and at the moment the car isn't on the road and won't be for about another 2 months due to restoring.... Is it even worth the hassle of resetting the ECU if I won't be driving it on the road for a while? If I should how do I do a proper reset?

Easiest way to reset it is to disconnect battery for 10 min... whether you should or not I don't really know

lots of hits on Google MR2 reset ECU.
 
Opinions vary as to the value:
 
eg: http://www.sopertek.co.uk.r2/service/index.htm#ecu
 
The donor ECU has already been reset by the amount of time it has spent on the bench

You can reset the ECU by puling the EFI fuse in the engine bay fuse box for 30 sec or so. 
 
I found it beneficial resetting the ECU when changing driving habbits, eg slow city running to longer runs every day.  This improved fuel economy by around 10% after the reset.
 
Cheers 

The only gay thing about the battery method is the clock is reset. Will try EFI method next time. Keep clock settings and 30s vs 10 mins no contest lol (especially if you want slightly aggressive fuel delivery by going for hard run while engine is hot)

When I do a reset by disconnecting the battery leads I rub the leads together and this discharges the car, do that for a couple of seconds then reconnect.. but then yes , you have the clock and radio to do :)