Duke doesn't crank anymore - Page 2 - KTM Duke 390 Forum
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post #11 of 27 Old 12-22-2016, 04:22 AM Thread Starter
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Maxime, Below is a thread which just appeared today on the RC390 forum. This owner has a problem rather similar to yours. The response is from Chad Wells, the most noted 390 tuner in the US and a long-time KTM dealer. He suggests the problem is low voltage caused by faulty connections or a bad battery.

No Start and JY_1.2.3 Displayed

To answer your question: It is not necessary to remove the fuel tank to access the starter relays. You do, however need to remove the tank cover , a plastic shroud that hides the tank as well as a number of electrical components. In the owner's manual there are instructions for removing the tank cover. Tedious, but not terribly difficult.
Ok, I will do that

Yep it sounds like the problem is similar (electronic). Since I checked the battery (and battery terminals), I will check the relays. I am just wondering if the K19 relay could also cause the problem, it controlls the starter motor M10, if it never closes, the M10 could not start.
I am just wondering why I have no error signal, or no reset of the dash board as he has.

Is there a particular procedure to test the relays or I do as I want ?

Thanks again !
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post #12 of 27 Old 12-22-2016, 10:11 AM
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One thought: All the starter relays appear to run through Fuse F1. I suggest you take off the pillion seat and check this fuse. It would not hurt to check all the fuses, just in case any may be melted. You also might want to pull out then re-insert the starter relays, as well as checking all their wiring connections. By ear or feel you should be able to determine whether a relay is functioning when the starter button is pressed. There should be an audible click, along with internal motion that can be felt with a finger.

Cheers, Will

"If you don't know where you're going, you might wind up somewhere else."
--Yogi Berra

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1980 Moto Guzzi V50 II (becoming a cafe racer)
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post #13 of 27 Old 12-23-2016, 10:06 AM Thread Starter
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I checked again all the fuses (under the pillion seat). There are all in good work condition.

Ground cable from frame to engine checked : OK (0V between the battery ground and the frame ground)
Cable from battery G10 to K19 checked : OK

I measured the difference of potential between K19 and M10. 0V when electric starter button IS NOT pushed. 0V when the button IS pushed. There is never a difference of voltage between the ground and positve terminal of the motor.

Therefore I decided to controll the K19 realy (before the others K18, K17 and K11) so I unplugged the input command signal (blue connector) from the K19 relay.
The black - yellow cable is the ground, and is OK (checked)
The yellow - red is the command from the auxilary starter relay.
I measured a difference of potential between those to cables of 0.2V when the electric starter button is unpressed wich I suppose is inducted volatage from other devices. When the electric starter button is pressed, I measured 8 ~ 10V, wich I think is good value. Does anyone has the datasheet of the K19 relay to check the range of voltage in wich the relay works ?

What do you think about it ? It could be a defect of the K19 that could cause the problem ?
Sould I also check the other relays or try just with a new K19 ?

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post #14 of 27 Old 12-23-2016, 12:01 PM
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If you don't hear an audible click at K19 when the starter button is pushed, then the circuit is clearly not being completed at that point. The low voltage (8-9V) you measured at the K19 command connector is suspicious - normally that voltage should be at least 12V, IMO. This lends credence to Chad Wells' diagnosis of a low-voltage issue. Before you change K19 I think you should investigate what might be causing a voltage drop at the blue connector. It is very possible that the voltage at that connector is too low to activate K19.

Cheers, Will

"If you don't know where you're going, you might wind up somewhere else."
--Yogi Berra

2015 390 Duke
1980 Moto Guzzi V50 II (becoming a cafe racer)
1984 Moto Guzzi SP 1000
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post #15 of 27 Old 12-23-2016, 05:44 PM Thread Starter
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If you don't hear an audible click at K19 when the starter button is pushed, then the circuit is clearly not being completed at that point. The low voltage (8-9V) you measured at the K19 command connector is suspicious - normally that voltage should be at least 12V, IMO. This lends credence to Chad Wells' diagnosis of a low-voltage issue. Before you change K19 I think you should investigate what might be causing a voltage drop at the blue connector. It is very possible that the voltage at that connector is too low to activate K19.
You were right, I tested the relay and it works perfectly, so the voltage at the blue connector is too low as you said.
Now I will check the the rest of the circuit and the relays.

Happy Chistmas Eve
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post #16 of 27 Old 12-24-2016, 10:42 AM
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If I encountered this problem the very first thing I would do is try to jump start from a car battery (car motor not running). The fact that a charged battery shows a surface charge of 13V or so doesn't mean it has enough oomph to turn the starter motor. Try the jump before starting to replace things.

"The major difference between a thing that might go wrong and a thing that cannot possibly go wrong is that when a thing that cannot possibly go wrong goes wrong it usually turns out to be impossible to get at or repair." -- Douglas Adams, The Hitchhikers Guide to the Galaxy
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post #17 of 27 Old 12-24-2016, 12:35 PM Thread Starter
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If I encountered this problem the very first thing I would do is try to jump start from a car battery (car motor not running). The fact that a charged battery shows a surface charge of 13V or so doesn't mean it has enough oomph to turn the starter motor. Try the jump before starting to replace things.
Already done before posting the thread

But it doesn't work, the bike does only crank but never starts (and never seems to want to).
I suppose that the drop of voltage somewhere in the circuit causes a low voltage which is not enough to supply the ignition coil or other devices.

I don't like the idea of checking every wire and connector but yeah "always look on the bright side of life".
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post #18 of 27 Old 12-24-2016, 01:00 PM
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I guess I'm a little confused, Maxime. Initially you said it didn't crank but you heard the little solenoid click, and later you said that it cranked but didn't start. Is that where it is now? Or am I still not getting the picture?

Which would not be the first time for me.

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post #19 of 27 Old 12-24-2016, 01:39 PM
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I guess I'm a little confused, Maxime. Initially you said it didn't crank but you heard the little solenoid click, and later you said that it cranked but didn't start. Is that where it is now? Or am I still not getting the picture?

Which would not be the first time for me.
A little confused also.

still if you can get it to turn over on the starter but it won't fire, then - how old is the fuel in it?

Also, you could remove the plug (awkward) and check for it sparking by refitting it to supressor cap and earthing it against the engine

Less is more - You can only use 150hp .001% of the time, but you can use 150kg 100% of the time ...........


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post #20 of 27 Old 12-25-2016, 07:00 AM Thread Starter
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A little confused also.

still if you can get it to turn over on the starter but it won't fire, then - how old is the fuel in it?

Also, you could remove the plug (awkward) and check for it sparking by refitting it to supressor cap and earthing it against the engine
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Originally Posted by Mikebet View Post
I guess I'm a little confused, Maxime. Initially you said it didn't crank but you heard the little solenoid click, and later you said that it cranked but didn't start. Is that where it is now? Or am I still not getting the picture?

Which would not be the first time for me.
Sorry for the misunderstanding, english is not my native language. I do my best but I might not use the proper word sometimes.

The engine doesn't start when the starter button is pressed; (when the bike is static) the crankshaft does not rotate because the electric starter is not rotating itself.

The crankshaft of the engine does rotate when the bike is pushed with a gear engaged; (when the bike is in motion and the clutch lever is released) the crankshaft does rotate but the engine never starts running. The oldchool manner to start a bike does not work.

Before posting the thread I also tried to "jump start" with a car battery as you proposed but it didn't work. I didn't particularly like the idea since the wire section of the Duke is not enough to have so much Amps flowing into it and I was afraid to burn something. I tried (despite my fear of damaging the circuit) and it was not successful.

After some voltage measures I concluded that the electric starter motor does not start running (despite new fully charged battery, good wiring and good ground) because the starter relay K19 never closes the power circuit. I checked if that relay was working by setting a potential difference of 12V between its command terminals and the solenoid closes the power circuit.

Then I measured a potential difference of 8V to 9V between the command terminals of the K19 which is not enough to supply the solenoid to close the power circuit. Since I should have 12V there, it means I have a drop of voltage somewhere in circuit due to a none-wanted resistance.

still if you can get it to turn over on the starter but it won't fire, then - how old is the fuel in it? I cannot get it turn over with the electric starter motor. Since it is a second-hand bike I just bought, I don't know how old the fuel is. Anyway, it runs perfectly one week ago.

Initially you said it didn't crank but you heard the little solenoid click, and later you said that it cranked but didn't start. The solenoid I heard was not the K19. It was another one (smaller than the K19) next to it (don't know which one). I was saying that it cranks (crankshaft rotating) when I was pushing the bike to start its engine (the oldschool manner). Still when the bike is static, the crankshaft is not set in motion because the starter motor is not powered by the battery.

I hope it is more understandable

Merry Christmas!

PS: Could someone define precisely what the verb to crank? I supposed that it means the crankshaft is rotating but now I not sure.

Last edited by Maxime_L; 12-25-2016 at 07:10 AM.
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