Man in the Car· Registered
'06 ZR +120 (HQM) '04 ZR 105 (IAB)
Your isue sounds more like a wiring fault - loose or corroded connector or damaged wiring causing a short. The lack of a 'gear change light' could be the bulb, or a broken or disconnected wire. None of the issues that you describe sound like Pektron SCU problems.
If you have a late 2003 on TF (with the Pektron SCU) , then that is probably the most likely reason.My horn works direct from battery. Have 12V but only 0.5A at the horn connector and I can here the relay make. Will this be the BCU relay at fault?