Forums 🚥 PiT STOP 🔧 Hyosung Technical Help Help with new wiring harness 2009 GT250r EFI Fuel injected model
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danielxen.
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Jun 22, 2025 at 11:05 PM #19836Bike Model = : 2009 GT250r EFI Fuel injected model
I bought a 2009GT250r EFI Fuel Injected model. The bike came without the main wiring harness but had the loom for headlight, front turn signals and cluster, purchased a second hand good harness and fitted to the bike.
I now have 2 x 2 pin plugs on the harness with nothing to plug then into.
One up with the headlight plugs, wires are Orange and Black with white tracer.
The other one is where the plug for the side stand wire and clutch loom connect, wires are Black with Yellow Tracer and White with Blue Tracer.
The bike starts and runs but headlight is not working, bulbs and fuses have been checked and all ok, high beam works with the pass switch on the left handle bar.
Help with where the wires connect and suggestions on the headlight issue would be appreciated.
Thanks
Paul -
Jun 23, 2025 at 7:41 PM #19843
Can you upload a picture please using the “Add Media” button , as you reply above the white text box ?
Try not to be too close as I would like to see where you’re grabbing it from. I myself or Simon will likely respond to what it is for.
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Jun 23, 2025 at 10:07 PM #19844
I cannot work out how to attach the photos.
I click on Visual, Insert/edit media, it then comes up with Source.
Do you have an email address I can send the photos to?
Thanks
Paul -
Jun 24, 2025 at 11:09 AM #19846
Depending on your device, upload a photo to OneDrive / GoogleDrive / DropBox and get a public share link. Paste the link here so we can see it.
I will redesign the site later the year to make it easier to attach photos on your reply
Source just means “where is the photo” , in this case if i am on the phone , i will navigate to the phone’s camera folder/gallery and select it. The site will pull the image in to the post.
Regards
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Jun 25, 2025 at 9:27 AM #19850
I have uploaded a video on YouTube, link below.
I also found a wiring diagram for the bike, from what I can see there in nothing to plug into either of the 2 plugs I have.
Wiring diagram is at the end of the video.
Hope this is helpful for you.Thanks
Paul -
Jun 25, 2025 at 8:25 PM #19856
At 3o seconds in:
The three plugs i see are for the main harnessThe headlights are connected the right way on that “mini pig-tail” harness. So it just needs to join the big harness on the bike.
The red bullet single wire , also matches the female side of the harness.3-pin plug = speed sensor (the flat one)
3 pin plug = lights (triangle shaped) => frame harness feeds it.
2 pin plug = Parking Light inside the top eye-ball of the bike.So in this case:
Verify that the Triangle 3-pIn plug and 2Pin plug have 12v coming out of them.
Remember = RIGHT SWITCH GEAR turns the Headlights ON or OFF (h1 and h3 bulbs)
The parking light (2 pin plug) is ALWAYS on regardless.
The LEFT switch gear will also control the headlights too (They work together with the right switch). Left Switch just toggles between Low or High Beam.Around 2:00 mark , you pulled out a 2 pin plug , now i am a little lost as i can’t remember where it connects to! – I would “assume” it is for either the airbox sensor or a diode along the harness but…the colour “black/yellow” at the front usually means ignition coil!
Check the wiring diagram for the ECU Connectors for that same “black/yellow” wire and where it goes? I have not seen that on the UK customer bikes i fix, so that’s puzzled me not unless , Hyosung has a funny habit of changing wire colours mid-cycle (they always do!)
Or it may be for the “EGR/AIS” (electric air valve) that takes air from airbox and dumps it to the cylinders near the exhaust pipes but i doubt it!
I can see the manual saying “BY” (Black/Yellow)” with no name to it , it must be left blank itentionally
Can you find a BY on the ECU side and follow the diagram to see where they end up?
I hope @syco (Simon) chimes in! 🧠 I’m having a weird brain fog at the moment
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Jun 26, 2025 at 10:14 AM #19860
Im struggling to remember what the 2 pin connector at the side goes to, it’s definitely not emissions stuff, I have a feeling it might be fuel gauge
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Jun 26, 2025 at 10:49 AM #19862
Im struggling to remember what the 2 pin connector at the side goes to, it’s definitely not emissions stuff, I have a feeling it might be fuel gauge
@syco – that one has puzzled me too as usually the fuel gauge connector is near the battery.I’ve not come across a 2-pin connector near the front coil in tandem with the side-stand plug. His video shows it but Hyosung blanked it? I suppose it is a dummy plug? (why would they make a dummy plug is beyond me) – I do know US and AU bikes do come with some strange extra bits on them like “canisters” or “black boxes” mounted to the sides of the frame for some emissions control or restriction?
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Jun 28, 2025 at 7:01 AM #19871
Update from today.
Removed the front headlight and fairing.
Fount the wiring for the 2 pin plug is looped in with the headlight wiring.
Checked all the bulbs, all good.
Tested for power at the 3 pin plug to the headlight 3 yellow wires, non of them were live or had power, also checked with the bike running.
Headlight relay was no good so swapped it out and rechecked, still no power and headlight not working, high beam does work using the pass button on the left handle bar.
Checked and cleaned the switch on the right handle bar.
Could the issue be the ECU?
Tail light and rear brake light works with front and rear brakes.
Any suggestions?
Thanks -
Jun 28, 2025 at 10:57 AM #19873
Check power to the ignition switch, ECU wont effect lights
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Jun 28, 2025 at 7:51 PM #19874
What simon said , also remember the “right switch” controls the headlight coming on or not for that specific GTR (ones with a black rpm counter and black lcd glass)
(Newer EFi models are “always on” regardless of the switch state)If you hear a “click” from the relay, then power should be going down your headlights.
Check for 12v at the relay sockets.
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Jul 3, 2025 at 9:28 AM #19899
Good news, all fixed.
Fitted new headlight relay and Switch assembly on RH handlebar, lights work and park light also working.
Thanks for all your help, great to have it all sorted.
Cheers
Paul -
Jul 4, 2025 at 5:17 PM #19904
Good news, all fixed. Fitted new headlight relay and Switch assembly on RH handlebar, lights work and park light also working. Thanks for all your help, great to have it all sorted. Cheers Paul
Yay! ⭐
Stay safe now
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Mar 21, 2026 at 8:53 AM #22127
Greeting from Romania! Paul, I bought last year a GT250 EFi that was switched to carb. I have the whole injection system and I’m trying to fit it back. After mounting the EFi loom, I get no spark. I checked fuseboxes and there is only one fuse. Could you send me pictures of your fuseboxes so I could fit mine? Thank you!!!
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