Finally I hope, after giving the ECU and the ECU harness plugs a good clean to remove all the corrosion there was some improvement, then it was suggested to check the main wiring harness plug under the tank, so I pulled it appart, can’t say I could see any corrosion on either plug but I gave them a very good clean with electrical cleaner, a blow out with the air hose and put back together. Did a three km ride and all is back to normal, horn works, speedo works, fuel gauge works, starts correctly hot and cold. Mitzzy was kind enough to loan me a ECU to try but I have not needed to use it yet.
Tomorrow night I will give it good ride before I will say it’s 100%,