2008 GT650R EFI – Starter motor not working

Hi guys!

A short introduction: My name is Maik, I’m from Germany, and I’ve been reading this amazing forum for quite a while. My son bought a 2008 GT650R EFI about two years ago. Now I have to help him fix it, and I hope you can help me.

What happened?

After a ride last week he parked the bike as usual. The next day it wouldn’t start anymore.

The ignition sequence looks normal: the dash comes up, the main relay clicks and the fuel pump primes. But when pressing the starter button, the only thing that happens is the fuel pump primes again. The starter motor doesn’t do anything.

I can already confirm that the starter motor itself is working. If I bridge it directly to the battery, it cranks immediately and the bike starts perfectly.

So I started checking the wiring diagram (thanks to whoever uploaded it!).

I have confirmed that:

the GR (Green/Red) wire going to the Mitsubishi ECU has continuity.
the starter button is working.
the clutch lever switch is working.

What I’m struggling with is the YR (Yellow/Red) wire.

According to the wiring diagram, it seems to go to some kind of “filter”, joins another wire there, and then somehow connects back to the GR wire. At least that’s how I understand the diagram.

The problem is that I can’t find those connection points. I can only follow the wire from the starter relay to the connector near the battery, and then I’m stuck.

At the moment I don’t really believe the ECU is faulty. Everything else seems to work fine, and the engine runs perfectly if I bypass the starter circuit. That’s why I currently suspect a broken wire, a bad connector, or maybe that mysterious “filter”.

Any ideas, explanations or suggestions would be greatly appreciated.

Thanks in advance!