[Solved] 2008 GT650R EFI – Starter motor not working
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Bike Model = : GT 650R EFI 2008
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!
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Thanks for your suggestion!
I’m pretty confident the battery is not the problem. It’s only about two years old, and just to be sure I also connected a car battery while testing. The behavior was exactly the same.
I also think the starter relay itself is OK.
If I manually connect the GR wire to battery negative and the YR wire to battery positive, the relay clicks immediately. If the starter motor is connected at the same time (I disconnected it for some of the tests), the starter cranks and the engine starts right away.
Maybe my understanding is wrong, but I would expect these control wires to receive the correct voltage during the normal starting sequence. I believe YR is the positive side of the relay coil.
To me it looks like the relay simply isn’t being driven by the bike’s wiring.
That’s why I’m currently thinking about a broken wire, a bad connector, or something else in the control circuit.
The only other possibility I can think of would be the ECU. But that doesn’t really make sense to me. Why would the ECU suddenly fail only in this single function? During the start attempt the fuel pump primes again, so the ECU is clearly alive and responding. The crankshaft position sensor must also be working, because once I bypass the relay the engine starts and runs normally.
So, at the moment, I’m leaning much more towards a wiring issue than a faulty ECU.
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It would be a wiring issue, the “start” button is what triggers the relay circuit but not every Hyosung model has a relay connected to the CDI (carby) or ECU (efi)
But i know that in my EFi experience , the relay does not click whatsoever if the ECU thinks the bike has a fault or the clutch switch is dead (replace, dont bypass) or the kickstand switch Bypass has corroded (check again the Kickstand bypass wires under the tape did not corrode) = These turn the relay off even on later carb models.
If its wiring, follow the wiring from the start button to the relay and ECU, then see if there is any reason the signal could get weak, perhaps too much resistance in the connectors (if the pins got too oxidized, we use contact cleaner to improve the situation, then there is enough signal / power along the lines to finally trigger the relay by the “start” button)
Bypassing the relay is forcing the starter motor to spin the magneto flywheel, and the ECU gets the pickup coil signals and is forced to fire up immediately (sort of like a push start) if all other sensors didn’t throw an error code stopping the ECU
If the ECU primes the fuel pump, it generally suggests its priming to fire up now. I know from experience my Delphi ECU will NOT prime the pump if i so much have a neutral switch not working! (It thinks i am still in gear)
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Guys, thank you all for your time and your ideas.
I think I finally solved the problem.
After following the wiring diagram and measuring everything I could, I became more and more suspicious of the mysterious “filter” (which I believe is some kind of diode pack).
For anyone who might have the same issue one day, here’s what I did:
I bypassed the “filter”. I never managed to find it physically, so I assume it’s hidden somewhere inside the wiring harness.
I cut the YR wire at the connector and ran a new wire directly to the YR wire at the starter switch.
It works like a charm, and all the safety functions (clutch switch, etc.) are still working as intended.
I also installed a diode in the new wire to prevent voltage from feeding back into the circuit. I’m not even sure it’s necessary, but I preferred to be on the safe side and protect the ECU.
Maybe this will help someone else in the future.
Thanks again!
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