I am looking to purchase a second hand ECU for my 1997 Toyota Starlet. The advert for the ECu states that it will need coding and I am unsure if this is something I can do or if I need an auto electrician to help. I did a quick bit of research and it states that if the car does not have an immobiliser then it should just be a case of swap it over and away I go. Any feedback would be greatly appreciated.
To slightly expand on @SolarMike's comment:
If the ECU is from the same year and model as your vehicle, it should almost just plug and play. However, you may have issues with the keys.
Many vehicles - everything modern, certainly, but I'm not sure about a '97 Starlet - have an immobilizer system. The ECM and/or BCM keep a list of known key codes. When you insert the key and attempt to start the car, the computers retrieve an ID from the key and compare it against a white list. If the key is known, the car starts. Otherwise... not so much.
Key programming is typically something a dealer has to do, though you may be able to find a locksmith with the proper equipment. I'd call a few local locksmiths and ask them. On some vehicles, you can find software that will let you pair keys to the car - I was able to do this with my '06 Infiniti with a 50 USD application and a 10 USD cable - but, on many cars, you'll need special equipment.
Regarding ECU programming: on some vehicles, you can do this with an interface cable and a laptop, as long as you can get the programming software and required firmware. But, again, if the ECU came out of the same year and model - and possibly a range of years, depending on what changes Toyota made on that car over the lifetime of the model - then I wouldn't worry about remapping.
Definitely figure out what you'll need to do regarding key pairing before spending money on this.