[Tutorial] Gear position sensor fault – Neutral switch GV 250 Aquila EFI 2010
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Bike Model = : GV 250 Aquila EFI 2010
📢 Admin Edit = Topic changed to a Tutorial because the member has solved it further down this post! 👍
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Hi, bought this bike on 8th November and rode it from Coventry to Livingston, but it has an intermittent fault with the Neutral light not coming on.Tested the voltages on the gear position sensor and they are :- 1st gear 0.34v neutral 5v 2nd gear 0.85 3rd gear 1.36 4th gear 2.01 5th gear 5v so that would seem to rule out bad connections etc. I would imagine that the voltage in neutral would be between the 1st and 2nd gear voltages unless all the voltages are a bit off because the one for neutral is not working right. It looks like the gear position sensor is faulty. I was just wondering if anyone could confirm the voltages I measured or if anyone had a similar problem what they did to fix it. An additional bit of information is that after switching the bike on and the neutral light not coming on, the FI light comes on after about 3 -4 seconds, then putting the bike in dealer mode causes the FI light to flash a code (31) which confirms a faulty gear position sensor. I have ordered a new GP sensor from Hyosung Wholesale, but it failed to arrive with the other stuff I also ordered at the same time – waiting for a reply from them. At the moment the neutral light does not come on at all.
Any thoughts or help would be appreciated – thanks
Kind regards
Robert -
The GP Sensor would need replacing yes , and also you can find some on eBay UK and eBay USA as these are still good 250cc markets , however be cautious using hyo sites that are blue and white , some riders on this forum have complained a lot resorting to asking PayPal to sort it out for them , unless they have genuine stock issues then they should give you an update.
A GP switch acting fishy does trigger the FI light as the ECU is expecting it and it assess (or guess as best as it can) to ascertain if you are in Neutral or Some other gear before starting, hence EFi versions have 5 contacts on the switch itself , carb models are not suitable as they are hit & miss with some 250 ECU’s – The carb versions have 1 contact point that says “Neutral On” or not , the CDI doen’t doesn’t typically care to sense if you are in Gear 5 or 1 , the EFi ones would , it helps with timings on the rest of the electronics.
Don’t throw it away, it will be a handy backup. Sometimes it does come back to life briefly – Get yourself some “stainless steel” bolts and a fresh O-ring if possible, that gearbox drum behind the sensor chucks a lot of oil!
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Hi, solved the problem with the neutral light not coming on and the FI light coming on.
It was the gear position sensor that was faulty, but I also measured it the wrong way. Here is how I think it should be:-
There are two wires coming from the sensor, one is blue and the other is brown. If you use a multimeter set to measure resistance you should see the following values when measuring from the BROWN wire to each contact on the gear position sensor (except neutral) 1st gear 99 ohms 2nd gear 295 ohms 3rd gear 505 ohms 4th gear 980 ohms 5th gear 1500 ohms. Measuring from the BLUE wire to the contact for neutral on the gear position sensor the value was 3 ohms, but I suspect this is just a direct contact to ground and my meter is not that accurate. On the broken sensor neutral and 5th gear was open circuit.
At the time I was trying to fix the problem, I could not find a second hand sensor or even a new one anywhere. So I bought a gear position sensor for a Suzuki GN250 from AliExpress for about £3 something. This sensor has seven wires on it, the black one is connected to the neutral contact so I removed the wire in the connector for 6th gear and put the black wire in its place the wire for 6th gear was just taped up out of the way as it is not needed. I wired up a plug to fit the socket that came with the sensor so that I have 5 resistors with values close to those mentioned earlier for each gear. The other end of the resistors are connected together and go to the brown wire. I have a 3 ohm resistor which is goes to the black wire in position 6 of the connector the the resistor is connected to the blue wire. This has been working fine for some time now and no oil leaks. I have attached a couple of pictures that might help if someone wants to try this themselves. You can see in the picture with the resistors that the one for neutral is separate from the others, this one is connected to the blue wire and all the other resistors are connected to the brown wire.
It should be noted that the flange of the sensor for the Suzuki is not as wide as the original, nor does it have the little brass inserts where the mounting bolts go, so you have to be careful when tightening the mounting bolts not to break the lugs where the bolts go through. It does fit and does seal ok even using the old “O” ring.
Hope this helps someone – at least to be able to measure the sensor to get an idea of the resistor values which might indicate whether the sensor is working or not.
oplus_34 
oplus_34 Kind regards
Robert -
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