Kubota - Strange electrical buzzing

[berky]

My B1750 recently started having issue with starting. I've gotten it to start before by cleaning up the ground connection on the frame. That doesn't seem to have fixed anything this time. I'm linking to 2 videos that show the issue. for google search purposes, here's a brief explanation of what I'm seeing:

Kubota Buzzing Videos (https://photos.app.goo.gl/QjdZbL5ZAmR9CutEA)

video 1:
- key on
- warming up glow plugs
- try to start
- lights go out immediately
- turn key off
- hear buzzing sound
- nothing works after that

video 2:
- key is off completely
- try turn signal; receive buzzing
- try lights; no buzzing

afterwards, when I disconnected the battery, and then reconnected it, the lights would at least come on again after turning the key, but i'm still getting the same behavior.

The battery at least appears to be good and charged... and it's relatively new battery. I had this issue a few weeks ago and "fixed" it by cleaning up the ground connection to the frame, but it doesn't seem to work this time.

Any ideas on what could possibly be the problem?

 

[BruceP]

There are not a lot of things on your tractor which would produce a 'buzzing' sound.
I would think that isolating the SOURCE of the 'buzzing' would be a good place to start.

video 2:
- key is off completely
- try turn signal; receive buzzing
- try lights; no buzzing

Based on this, I would suggest you check to see if it is the turn-signal "blinker" relay which is buzzing.

=================================

I've gotten it to start before by cleaning up the ground connection on the frame.

It would not hurt to do some VOLTAGE DROP measurements using a voltmeter. This is the only accurate way to isolate bad connections within high-current circuits. (Ohms readings are not reliable)

At the very minimum, validate the main ground and power distributions using VOLTAGE DROP measurements.

 

[Captain13]

Could be a bad relay. On my tractor, they are behind the instrument panel. A faulty relay may just vibrate instead of pulling the contacts together. Most of the relays are the same p/n so you can switch from one location to another to help find the bad one if that’s your problem.

 

[BruceP]

Could be a bad relay.

Technically not a "bad" relay... but a specific condition which can make a relay 'buzz'.

A relay can only 'buzz' under one condition.... but I hesitate to describe it here unless it is relevant to the discussion.

Lets wait for the OP (Original Poster) to get back to us regarding specifically where the 'buzz' is coming from.

 

[Quick]

Although it might not be the problem, a bad battery can present those symptoms. Put jumper cable on it. If it solves the problem, there ya go. If it doesn't, you've easily eliminated a potential source of the problem. (-:

 

[berky]

Technically not a "bad" relay... but a specific condition which can make a relay 'buzz'.

A relay can only 'buzz' under one condition.... but I hesitate to describe it here unless it is relevant to the discussion.

Lets wait for the OP (Original Poster) to get back to us regarding specifically where the 'buzz' is coming from.

Wow... not sure why I wasn't getting updates when people were responding.

anyway, the buzzing sound kinda seems to be coming from 'under' the steering column area, like between where your feet go, if that makes sense. I was away all weekend, so I'm going to get back to figuring this out.

EDIT: buzzing is definitely coming from right behind the 'panel' where the turn signal is. very well could be a relay behind there.

side note: sometimes when I turn the key, no lights come on at all. I can get them to come on by disconnecting the battery and reconnecting it. almost as if i'm "rebooting it" haha. I guess there could be a capacitor that gets cleared or something like that maybe?

 

[berky]

Although it might not be the problem, a bad battery can present those symptoms. Put jumper cable on it. If it solves the problem, there ya go. If it doesn't, you've easily eliminated a potential source of the problem. (-:

I've tried that first, but with a battery charger... no change.

 

[hagrid]

anyway, the buzzing sound kinda seems to be coming from 'under' the steering column area, like between where your feet go, if that makes sense. I was away all weekend, so I'm going to get back to figuring this out.

Something similar happened to me except it was coming from my fiancee's night stand.

 

[Dave_eng]

I've tried that first, but with a battery charger... no change.

Please post photo of the top of your battery.
I am looking for replacement cable ends.

If you have anything that looks like one of the above, invest in a complete new cable.
These ends also render boosting or help from a battery charger useless.

Dave

 

[berky]

Please post photo of the top of your battery.
I am looking for replacement cable ends.
View attachment 81739
View attachment 81740
If you have anything that looks like one of the above, invest in a complete new cable.
These ends also render boosting or help from a battery charger useless.

Dave

I think I have at least 1 of what you're referring to. what type of ends do you recommend?

 

[D2Cat]

I'm sure Dave is suggesting a store purchased end with cable going into the clamp for the battery post with no other clamps/bolts/connections on the battery end. Opposite end (since it is battery positive) will go to the starter and therefore have an eye to go over the stud there. Since you're purchasing new, get a red cable!

 

[berky]

There are not a lot of things on your tractor which would produce a 'buzzing' sound.
I would think that isolating the SOURCE of the 'buzzing' would be a good place to start.



Based on this, I would suggest you check to see if it is the turn-signal "blinker" relay which is buzzing.

=================================


It would not hurt to do some VOLTAGE DROP measurements using a voltmeter. This is the only accurate way to isolate bad connections within high-current circuits. (Ohms readings are not reliable)

At the very minimum, validate the main ground and power distributions using VOLTAGE DROP measurements.

Here's what I have for voltage measurements... let me know if I did something wrong or if you want other data.

Battery terminal neg to pos - 12.91
Battery terminal neg to front of starter (bottom location in pic) - 12.91
Battery terminal pos to front of starter (top location in pic) - 12.91
Battery terminal pos to tractor frame - 12.92

 

[SDT]

Confused about symptoms but bu

My B1750 recently started having issue with starting. I've gotten it to start before by cleaning up the ground connection on the frame. That doesn't seem to have fixed anything this time. I'm linking to 2 videos that show the issue. for google search purposes, here's a brief explanation of what I'm seeing:

Kubota Buzzing Videos (https://photos.app.goo.gl/QjdZbL5ZAmR9CutEA)

video 1:
- key on
- warming up glow plugs
- try to start
- lights go out immediately
- turn key off
- hear buzzing sound
- nothing works after that

video 2:
- key is off completely
- try turn signal; receive buzzing
- try lights; no buzzing

afterwards, when I disconnected the battery, and then reconnected it, the lights would at least come on again after turning the key, but i'm still getting the same behavior.

The battery at least appears to be good and charged... and it's relatively new battery. I had this issue a few weeks ago and "fixed" it by cleaning up the ground connection to the frame, but it doesn't seem to work this time.

Any ideas on what could possibly be the problem?

Confused about symptoms but "buzzing" while trying to crank engine is often caused by low voltage at solenoid.

FWIW, my B1750 has developed an intermittent no crank issue which has been difficult to diagnose due to intermittent nature.

To date EVERYTHING in the cranking circuit has been replaced except a small wireng harness between the key switch and solenoid, which is NLS.

Waiting for a hard failure to definitively determine cause of no crank.

SDT

 

[Mark_BX25D]

I think I have at least 1 of what you're referring to. what type of ends do you recommend?

I'm a big fan of military battery terminals, available at various vendors, both online and brick & mortar. Some people like marine terminals, which are also good. Top clearance for these can be an issue in some applications.

If you need cables, check out BestBoatWire.com Made to your order; cables, connectors, heat shrink. I like to get the clear heat shrink so I can see what's going on under there. I've had quite a few cables made by them, and the quality, price, and service have been very good.

 

[Mark_BX25D]

Confused about symptoms but "buzzing" while trying to crank engine is often caused by low voltage at solenoid.

True.

A mechanic's stethoscope can be a huge help in tracking down strange sounds. You'll be amazed at what you can hear with one. For ten bucks or less, every DIY mechanic should have one. Even a Harbor Frieght El Cheap is a wonderful tool.

 

[BruceP]

Here's what I have for voltage measurements... let me know if I did something wrong or if you want other data.

Battery terminal neg to pos - 12.91
Battery terminal neg to front of starter (bottom location in pic) - 12.91
Battery terminal pos to front of starter (top location in pic) - 12.91
Battery terminal pos to tractor frame - 12.92

All of those measurements are EXPECTED when machine is sitting and no current is passing thru wires.

Two basic voltage-drop measurements:

1. Master Ground wire
   1. Neg meter lead on BATTERY MINUS post (not on the connector!!!)
   2. Pos meter lead on ENGINE CASTING
   3. Measure voltage WHILE CRANKING ENGINE
   4. expect less than 0.050 volts (50mV)
2. Master power to starter
   1. Neg meter lead on BATTERY POSTIVE post (not on connector!!)
   2. Pos meter lead on LARGE wire on starter bendix
   3. Measure voltage WHILE CRANKING ENGINE
   4. expect less than 0.050 volts (50mV)

After you have checked the above two measurements, the results will lead us to the next step.
Anything more than 0.050v should be considered a problem.

"buzzing" while trying to crank engine is often caused by low voltage at solenoid.

BINGO!!! This is the ONLY thing that can cause relay/solenoid to 'buzz'

Here is the sequence of events:

1. Relay coil receives enough voltage to 'pick' normally
2. When the relay-contacts connect, the electrical load causes the voltage at the relay-coil to drop
3. low voltage at coil causes relay to release (hence disconnecting electrical load)
4. With electrical load removed, the voltage at the coil rises enough to 'pick' the relay again
5. BACK TO STEP #2 ABOVE

The above sequence happens VERY quickly (many times a second) hence our ears hear the repeating relay pick/release as a buzzzzzzzzzzzzzz.

While buzzing, it is trivial to feel the relays with your fingers and locate the one which is making the noise.
BEWARE: The relay is RARELY the problem.... just a symptom.

 

[berky]

It seems the edit to my one post didn't save, so I'll post here so I know people see it.

In the post with the voltage readings, I incorrectly stated "starter" when it was actually the "solenoid".

Also, I tested the terminal connection with the key in the 'on' position.

The reading for the neg to pos terminal went from approx 13 to around 2.3 volts

then I connected jumpers to my truck and it was back up to just over 13 volts

with the jumpers still on, the reading from neg terminal to solenoid was at the 2.3 volt reading, but the pos terminal to the solenoid was still around 13 volts

Am i doing these readings correctly or should I check voltage somewhere else?

 

[BruceP]

Am i doing these readings correctly or should I check voltage somewhere else?

Please reread my post #16

I describe in detail where to clip the meter-leads , what conditions to take the readings, and what numbers to expect.

 

[Dave_eng]

Here is an Amazon example of what I am recommending you get.
Any automotive parts place will have them in different lengths.

I would suggest you also replace the negative cable.

Dave

 

[BruceP]

Here is an Amazon example of what I am recommending you get.

One caveat to beware of.... A LOT of the electrical stuff available on 'Amazon' use ALUMINUM wire...or even worse, STEEL wire. (sometimes coated with thin layer of copper-cladding to make it appear like copper)

Be aware that anything less than copper will not conduct electrons as well. (will have higher voltage-drop across wire) Your starter will not spin as fast.