DCT gear position Issues

[De Junior 4]

Hi Folks, 

I bought my Honda NC750X DCT 3 weeks ago, and as new rider I was enjoying it until today the 10.05.2020. I went from home to my friend home and was the first time using the MT, and all worked accordingly. On my way back, the gear position on D - mode, stuck on 1 gear and even accelerating up to 5000 revs and 40km/h it did not change to 2 neither up shift. Tried on S mode, even on Manual Mode nothing happen. The gear position stuck in 1 until reach home. 

 

Please help on my issue. The ABS light was flashing while riding and gear position disappeared just '-' was there blinking. 

 

Regards

 

Daniel Junior

Angolan

NC owner. 

[MatBin 5,080]

I believe if you ride it in MT mode it won't change up, only down.

Try again in full auto mode and see if it changes gear ok. Perhaps you had it in AT mode on the way to your friends without realising it.

[De Junior 4]

Hi Mat, 

 

Even in MT mode using the up and downs shifts it won't go to a second gear, remains on 1. 

I have tried on AT mode D and S, nothing... remains on 1 gear position. 

 

The ABS light keep on blinking. 

 

Regards 

[MatBin 5,080]

Did you buy it from a dealer? Or private? If dealer then take it back and get them to sort it out under warranty, otherwise just take to dealer for them to check if out. How old is it and how many miles/km has it done?

[De Junior 4]

I bought private. It has 14.750Km and it is from 2015. I will see the mechanic tomorrow. I have checked the oil level with engine cold and it is very low. I will check tomorrow with engine warm. 

 

Regards 

[MatBin 5,080]

That's a little over a service interval, do you know if it received a service recently, sounds like it probably didn't.

Be very careful which oil you use, the DCT gearbox is very particular as to what oil you use. Car type oil must be not be used and it should be 10/30 not 10/40 type. Check the manual for the oil specifications.

I have asked moderator to move this to "service" area, or you could put another post in that section, might get a better response.

Edited May 10, 2020 by MatBin

[De Junior 4]

Ok Many thanks. 

The last service was last week. Engine oil changed, Oil Filter and Air Filter, 

 

Thanks

[MatBin 5,080]

2 minutes ago, De Junior said:

Ok Many thanks. 

The last service was last week. Engine oil changed, Oil Filter and Air Filter, 

 

Thanks

Added some new replies, see above amended post. Who did the service?

[De Junior 4]

My local mechanic. Not Honda one. 

 

[Andy m 23,502]

The ABS light suggests the battery voltage is low. I'm betting the battery is 5 years old? Nothing like a reading of 0.5 to blow the mind of a binary system. 

 

Andy

[Gringo 5,074]

1 hour ago, Andy m said:

The ABS light suggests the battery voltage is low. I'm betting the battery is 5 years old? Nothing like a reading of 0.5 to blow the mind of a binary system. 

 

Andy

Beat me to it Andy. ABS flashes does suggest a low battery. I'm assuming the gear change mechanism requires a fair few amps to the DCT system for it to operate correctly?? Really not sure how the DCT works but there must be electronics involved somewhere maybe? The battery won't recharge on short runs so putting something like an Optimate on when the bike is not in use will keep it topped up. If the battery is 5 years I'd say its getting past it's prime. So, before heading to a dealer, charge the battery up and see if that cures the fault. 

On the BMW R1100RT I had the ABS would flash sometimes and this was caused by poor battery voltage. Charging it cured the fault. 

[Andy m 23,502]

DCT to me is going to work like AS-Tronic or the ZF automated gearboxes. The calculated torque from the RPM and speed tells it when to change up. The actuators will have a fairly hefty current draw. It needs to cut the ignition as it changes up which is a CANBus like signal to the engine. If a sensor reading is out of range or there is a lack of certainty about completing the move, it stays where it is.

 

ABS doesn't like low voltage because the change in wheel speed is calculated from feeding a raw sine wave back over a chopped square wave created by the electronic. When the voltage drops the square wave amplitude drops so the crossing point of square and sine is no longer an accurate presentation of the wheel. It would work down to about 11.8V, but when you can charge £60 an hour to watch a battery tender, safety springs to mind and they latch the light at 12.3!

 

Andy

[rjp996 1,091]

I had very odd gear position issues on my AT when the battery was very low - I assumed that once I had it started, the 14v from generator charging the battery would make the gear selector issues go away, as it had a good voltage.... but it didn't.. put it on the charger and once charged it all worked fine (im still a little puzzled, shows you cant ride with a duff battery even once you get it started.).

The only other thing I would check out is the ABS sensor, once you checked the battery  (I would leave lights on for a bit with bike off to remove surface charge in battery, and then crank it over and see what the volt drop is - dips into the 8-9v and indication of an issue

[De Junior 4]

Gringo, 

 

The battery was changed already, i spoke to the preivous owner. 

 

Regards 

[De Junior 4]

1 hour ago, rjp996 said:

I had very odd gear position issues on my AT when the battery was very low - I assumed that once I had it started, the 14v from generator charging the battery would make the gear selector issues go away, as it had a good voltage.... but it didn't.. put it on the charger and once charged it all worked fine (im still a little puzzled, shows you cant ride with a duff battery even once you get it started.).

The only other thing I would check out is the ABS sensor, once you checked the battery  (I would leave lights on for a bit with bike off to remove surface charge in battery, and then crank it over and see what the volt drop is - dips into the 8-9v and indication of an issue

 

Is it possible that the ABS blinking is the cause of the gear not shifting from 1 to up gears? Because even if I accelerate to 40km/h it does not change gear. 

 

Advise. 

[MatBin 5,080]

Can you shift using the paddles/switches on the left bar?

[Andy m 23,502]

The two aren't really linked. The ABS has its own complaint but is not active. If it were cycling it may effectively tell the gearbox not to change but you'd hear and feel that. 

 

The places both are linked is the power supply and only if Honda wanted to be really crude the ABS. Not linking to the ABS sensors, using the flywheel makes more sense as it lets them sell the bike in the USA where automatics are popular but they don't like to pay for safety.

 

Blink code the ABS and see if you have a sensor or power supply fault. 

 

 

I can't remember where the red plug is on the NC but there will be one.

 

Andy

[SteveThackery 3,090]

5 hours ago, Andy m said:

It needs to cut the ignition as it changes up which is a CANBus like signal to the engine.

 

Not the case with DCT transmissions, only quick shifters.  DCT systems modulate the fly-by-wire throttle or the ignition timing (just like an automatic transmission on a car), and the clutches are carefully overlapped to keep the engine revs steady.

On mine, if I had 10W-40 oil in it, the engine would blip during up-changes when cold as the clutches couldn't overlap properly.  10W-30 cured it.

[SteveThackery 3,090]

1 hour ago, Andy m said:

The two aren't really linked.

 

They are on the NC.  If a good signal is not received from both wheel sensors, it won't change out of first gear.

 

If you've got a centre stand you can try it: select D with the back wheel in the air.  Because the front wheel isn't turning (thus generating an ABS signal) but the back wheel is, your ABS light flashes and it won't change up through the gears.

 

Edited May 11, 2020 by SteveThackery

[Andy m 23,502]

Yuk, how very 1980's.

 

Blink coding the ECU remains the best way to find out if a sensor signal is the problem. This ABS ECU though isn't bright enough to tell you if it's open circuit, a dinged polewheel, an open circuit or short of some sort, or even a problem with the DCT feeding back. Get the multimeter out at that point I guess.

 

Andy

[MatBin 5,080]

21 minutes ago, Andy m said:

Yuk, how very 1980's.

 

Blink coding the ECU remains the best way to find out if a sensor signal is the problem. This ABS ECU though isn't bright enough to tell you if it's open circuit, a dinged polewheel, an open circuit or short of some sort, or even a problem with the DCT feeding back. Get the multimeter out at that point I guess.

 

Andy

I think I'd bite the bullet and take it to a dealer, isn't just the ABS ECU that isn't bright enough (in my case).

There's some great advice in this thread, shows just how complicated the "simple" NC really is, especially in DCT guise.

[De Junior 4]

3 hours ago, MatBin said:

Can you shift using the paddles/switches on the left bar?

Does not work either... I took it to mechanic and it is the ABS malfunction, I left there for repair and tomorrow will get it back. 

 

 

[MatBin 5,080]

7 minutes ago, De Junior said:

Does not work either... I took it to mechanic and it is the ABS malfunction, I left there for repair and tomorrow will get it back. 

 

 

Thanks for letting us know.

[De Junior 4]

Hi Guys, 

 

unfortunately he can not repair the sensor only replace and there is no ABS sensor for my Bike here in my country (Angola). I will need wait until Coronavirus passes to buy abroad. 

 

Regards 

[De Junior 4]

Guys, 

 

Can anyone help me by referring to a website where I can find the ABS Sensor? 

 

I really need it.

 

Regards