Voltage drop to starter

[Strodad]

The tractor I am dealing with is a 1990 L2850 Kubota. I originally thought I had a relay issue, but after getting a wiring schematic I do not see a starter relay. The issue is a voltage drop to the starter from the key. I am only getting 9 volts. I see where the key wire to the starter solenoid is labeled as "2-BW and stays that way on both sides of the safety switch. It changes to 2-BR and continues to the key switch.
I cannot see anywhere that the voltage would be dropped. I will be pulling the switch and taking a reading at the main post and the starter connection.
Can anyone think of anything else?

BR

 

[SDT]

The tractor I am dealing with is a 1990 L2850 Kubota. I originally thought I had a relay issue, but after getting a wiring schematic I do not see a starter relay. The issue is a voltage drop to the starter from the key. I am only getting 9 volts. I see where the key wire to the starter solenoid is labeled as "2-BW and stays that way on both sides of the safety switch. It changes to 2-BR and continues to the key switch.
I cannot see anywhere that the voltage would be dropped. I will be pulling the switch and taking a reading at the main post and the starter connection.
Can anyone think of anything else?

BR

Assuming that you are dealing with an intermittant no crank issue.

I have a similar issue with my 1994 B1750 and have eliminated EVERYTHING aside from the short wireing harness between the keyswitch and starter. This is the first part that I have ever tried to get from Kubota that is NLS. Plan to replace the wire and terminals in the harness but have not yet done so.

Corrosion can occur iniside wireing insulation or other places not apparent by visible inspection.

 

[Strodad]

Assuming that you are dealing with an intermittant no crank issue.

I have a similar issue with my 1994 B1750 and have eliminated EVERYTHING aside from the short wireing harness between the keyswitch and starter. This is the first part that I have ever tried to get from Kubota that is NLS. Plan to replace the wire and terminals in the harness but have not yet done so.

Corrosion can occur iniside wireing insulation or other places not apparent by visible inspection.

Yes I have the intermittent no crank issue as well. I thought relay then I checked the solenoid. Now I plan to check voltage at the back of the switch.

 

[Dave_eng]

I was surprised to see the WSM has a 6 volt battery used to test the operation of the starter solenoid.

Have you tried jumping the starter to verify it itself is not faulty?

The jumping needs to be done with great care as you can get run over. Best to have someone in the seat with the brakes applied.

Many owners of the older tractors which do not have a start relay find adding one makes starting much more reliable.

John Deere has a relay kit but if you are at all handy with electrics, a headlight relay for $10 is all you need.

Could you please describe how you are measuring the 9 volts and what position the key switch is in.

Dave

 

[Strodad]

I was surprised to see the WSM has a 6 volt battery used to test the operation of the starter solenoid.

View attachment 72588
Have you tried jumping the starter to verify it itself is not faulty?

View attachment 72589

The jumping needs to be done with great care as you can get run over. Best to have someone in the seat with the brakes applied.

Many owners of the older tractors which do not have a start relay find adding one makes starting much more reliable.

John Deere has a relay kit but if you are at all handy with electrics, a headlight relay for $10 is all you need.

View attachment 72590

Could you please describe how you are measuring the 9 volts and what position the key switch is in.

Dave

I am getting the 9 volts from the switch wire on the solenoid with the key turned in the start position. I would think that I should be getting 12 volts to the starter wire from the key.
I had to clean out the dirt and ice in the solenoid from the lug on top not having an environmental seal on it. I think it was assembled wrong at the factory, it was probably a Friday at closing time. Ha Ha

 

[GBJeffOH]

You could unhook the small wire from the starter. Have someone hold it in start. Use a volt meter to see where the drop is.

The terminal on the left is a pull in winding that draws a lot of amps.

The terminal on the right goes to the bottom post is the hold winding. Draws less amps.

 

[Strodad]

You could unhook the small wire from the starter. Have someone hold it in start. Use a volt meter to see where the drop is.

I had already done that and measured 9 volts at the small wire with it disconnected from the solenoid.

 

[Henro]

I had already done that and measured 9 volts at the small wire with it disconnected from the solenoid.

IF all you get is 9 volts with the wire off the starter solenoid terminal, if you meter is accurate, you should know you have an issue in the wiring.

If you follow Daves advice and the tractor turns over normally, you will have confirmed you have an issue in the wiring circuit feeding the starter solenoid.

But it is surprising you would only measure 9 volts with the circuit open circuited and your voltmeter on the end of the circuit. Without changing anything if you move the meter leads to the battery terminals, what voltage do you read? Simply a check of the meter.

Follow Dave’s suggestion and see if the tractor starts. Then report back.

Generally if you measured low voltage on the starter solenoid terminal with the wire connected to it this would indicate an issue with something in the circuit dropping voltage due to increased resistance. BUT with the wire off the solenoid terminal you should measure very close to battery voltage with your meter. This is because the meter draws very little current when making the measurement, so even with increased resistance in the circuit, that would affect normal operation, you should still read very close to battery voltage with your meter, since very low current flows when taking the measurement, and therefore very little voltage is dropped over resistances in the circuit.

 

[Mark_BX25D]

Corrosion can occur iniside wireing insulation or other places not apparent by visible inspection.

Bingo. If you are going to troubleshoot a problem like this, don't rely on your eyeballs, with or without glasses. Take connections apart (and clean them up while you are at it). Pull, push, and twist on those cables. If it's marginal, you want to break it. Once it's broken, you know what needs to be fixed or replaced. When it's marginal, you are still in the dark.

If the cables are suspect, you can buy new ones from the dealer, or get new ones made.

Check out BestBoatWire.com Made to your order; cables, connectors, heat shrink. Choose your terminal size and type. Make 'em like you want 'em. Maybe even bump up one gauge size over factory.

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.

 

[SDT]

The tractor I am dealing with is a 1990 L2850 Kubota. I originally thought I had a relay issue, but after getting a wiring schematic I do not see a starter relay. The issue is a voltage drop to the starter from the key. I am only getting 9 volts. I see where the key wire to the starter solenoid is labeled as "2-BW and stays that way on both sides of the safety switch. It changes to 2-BR and continues to the key switch.
I cannot see anywhere that the voltage would be dropped. I will be pulling the switch and taking a reading at the main post and the starter connection.
Can anyone think of anything else?

BR

Another factor to consider is glow plugs.

Depending upon model, it is likely that the glow plugs are energized with the key in start. Glow plugs draw considerable current. A battery with high IR or weak wireing or connectioins between the battery and key switch could rersult in low voltage at both glow plugs and solenoid.

 

[GreensvilleJay]

re: I was surprised to see the WSM has a 6 volt battery used to test the operation of the starter solenoid.

According to the wiring diagram, the starter solenoid has a 'tapped' coil so only 6 volts is needed to 'pull in' the solenoid. Once the plunger is down, battery +12 is applied to the coil to keep it fully down ,while the starter is spinning.

ANY resistance from the battery---?ignition switch--->safety switches-->solenoid will reduce the current to the coil. The JD 'system' is a 'bodge' to get around replacing bad ign switches, corroded wiring and funky safety switches. Replace all that stuff could cost $200+ so a $10 relay is a good deal.

 

[lmichael]

Here is what I did to fix same exact issue(s) on my G2160.

Another No starter rotation thread

My M4700 is a pretty simple tractor...or so I thought... Only one safety switch activated by the range-lever (the forward-Reverse-Low-High selection lever) on this DT (manual transmission.). The neutral start safety switch is kind of troublesome to get to... and that was my suspicion because...

www.orangetractortalks.com

It's painless to do, cheap and done right works 100% and looks like OEM

 

[GeoHorn]

Here is what I did to fix same exact issue(s) on my G2160.

Another No starter rotation thread

My M4700 is a pretty simple tractor...or so I thought... Only one safety switch activated by the range-lever (the forward-Reverse-Low-High selection lever) on this DT (manual transmission.). The neutral start safety switch is kind of troublesome to get to... and that was my suspicion because...

www.orangetractortalks.com

It's painless to do, cheap and done right works 100% and looks like OEM

I was a bit confused by your pics… then realized what you’d done. Glad it worked for you.

STODAD… in the thread linked-to above,…I was the originator of that thread...and if you want to get to the “meat” of the troubleshooting and the solution… be certain to read post #6 in that thread.

 

[Strodad]

Another factor to consider is glow plugs.

Depending upon model, it is likely that the glow plugs are energized with the key in start. Glow plugs draw considerable current. A battery with high IR or weak wireing or connections between the battery and key switch could result in low voltage at both glow plugs and solenoid.

Well the battery is two months old and is a Kubota replacement( cost $5 more than an Interstate), the cable from the positive to the starter is super heavy ( looks like 10mm), I also replaced the ground with the same wire and it terminates on the starter top mount bolt.
I did not think about the glow plugs as being part of the draw, that would explain only 9 volts because each plug pulls about 1 volt and a fair amount of current to work correctly.
I cannot just pull panels off and check wires, unfortunately the panels are all inter- locking and I pain to remove and replace.

 

[lugbolt]

do a voltage drop test.

look at your wsm wiring diagram. Find on the tractor where the trigger wire comes from (source is the battery, then fuse, then key switch, then switches) and everywhere there is a connection there is possibility for a voltage drop. Using your dvom, test each connection and each switch individually. You will find your problem.

 

[lmichael]

I spent hours on hours looking through every switch and connection I could get my grubby paws on with my Fluke. I gave up. Installed the relay system (which honestly Kubota should have done from the get go), and issue solved. Works every time. Honestly the glow plugs are NOT the issue. I also tried new battery, new starter, new "ignition" switch. No help. Do the relay. It's "da bomb".

 

[GreensvilleJay]

The 'relay bypass' works because the Made in China relay requires less current to energize than the 30 year old OEM solenoid. Since you replaced the ignition switch, it's the 30 years old wiring and safety switches that caused the problem. Less costly bodge is to just add a $2 pushbutton between +12 battery and starter solenoid.
The reason why Kubota Deere and others didn't/don't install that extra relay is cost. Extra parts,wires, install time,inventory, etc. All of which hits their 'bottom line'.

 

[lmichael]

The 'relay bypass' works because the Made in China relay requires less current to energize than the 30 year old OEM solenoid. Since you replaced the ignition switch, it's the 30 years old wiring and safety switches that caused the problem. Less costly bodge is to just add a $2 pushbutton between +12 battery and starter solenoid.
The reason why Kubota Deere and others didn't/don't install that extra relay is cost. Extra parts,wires, install time,inventory, etc. All of which hits their 'bottom line'.

Still FAR better solution than adding a button. It works and looks like a factory install. Likely better! Plus it keeps all the safety devices INTACT and functioning. Yeah, having come off a nearly 60 yo Allis B series with absolutely no safety device(s) (not even belt guards) may seem superfluous. But, I wanted it to look and function exactly as stock. And beside, who cares where my relay was made? And yeah OF COURSE it needs less current (that is the whole point of relays anyway. Not to mention you have relay and solenoid functions mixed up. What's on the starter is a SOLENOID meaning of course it needs FAR more current because it's an electromechanical device. Technically the relay is only a switch used to take low current and allow high current to pass. Glad you like your button. You would have been ecstatic over my old Aliis BTW

 

[GreensvilleJay]

re: Not to mention you have relay and solenoid functions mixed up.
No, I don't, in this case BOTH devices are electromechanical devices where a small current is used to control a large current. Solenoid,relay,contactor are all the same.
As for where made. The crappy MIC ones for riders are terrible compared to the MinUSA ones I used to buy. Fortunately I've gone 'solid state' on several machines,replacing relays or solenoids with transistors.

I LOVE Allis-Chalmers tractors, had 2 B,1C, 1CA, 4 D-14, 3 G, 1 forklift and a Gleaner A. The A-C Snap-Coupler implement is still the BEST way to 'hookup and go'.

 

[BruceP]

The issue is a voltage drop to the starter from the key. I am only getting 9 volts.

The most-efficient way to troubleshoot a voltage-drop is to use VOLTAGE DROP MEASUREMENTS using a voltmeter.

Essentially:

• Clip one lead of the voltmeter on the point where you are seeing the low voltage (the small connector on starter) This DOES NOT MOVE from this point as you make measurements.
• Use the other voltmeter lead to measure the VOLTAGE DROP through the circuit. (Start with lead on battery-positive for initial test) Keep moving this lead to new positions as you attempt to start.

Ideally, you are looking for 0.00v voltage-drop thru a wire... in reality, anything less than 0.050 is acceptable.

Since you are only seeing 9v at the starter, this means you are loosing 3 volts in the circuit somewhere. Just keep moving the lead and re-trying to start until you isolate the problem.

It should take less than 10 minutes of VOLTAGE DROP measurements to isolate where the problem exists.

-------------------------
Another workaround (which I did to my Kubota) is to install a small 12v relay near the starter. The wire which USED to go to the small connector on the starter now simply picks this new relay. It is the relay which feeds the starter directly from the battery positive.

In this way, the voltage-drops thru all the safety-switches does not affect starting while still maintaining all the safety features.