I think my starter is bad. What else should I be looking at before buying a new starter?

[Wull]

If the starter checks out and works, test the main battery feed cable to the starter, the positive cable that goes to the starter. You can test it for continuity but what I like to do as it sometimes might show 12v but falls on its arse when you try and start it is remove that cable from the equation and attach a jump lead, so run a jump lead from the battery positive terminal to the 12v constant feed pole on the starter, you have to keep the 12v ignition circuit connector on the pole.

When setting this test up make sure you remove the negative first before you start removing stuff, then once you’ve got it set up put the negative back on and see if it will start then.

Check to see how good your ground is as well, test for continuity between the earth cable and where the starter mounts to the casing, if this checks out your ground is more than likely perfectly fine.

 

[country_hick]

I put a newer cab on my rusty old plow truck. After getting everything together it would not start. It should have started easily. Although the cable going to the starter looked good it has just enough corrosion on the cable end where it bolted onto the starter to prevent it from getting enough current to start. After I shined up the metal (probably wire brushing, maybe using fine sandpaper) so it went from looking good to looking very shiny. The truck then started easily and still does over 20 years later.

You would be amazed at how just a little discoloration on the starters electrical lugs (bolts) and the electrical cable can prevent you from starting. Cleaning up all the electrical contact points is always job #1 when a starter just clicks.

If you are only getting 12.0 volts at the battery your battery has a problem. It could need to be charged because the alternator is not charging it (maybe because of dirty electrical connections) or the battery may need to be replaced.

It would be a good idea to charge the battery and see if that makes a difference. Batteries do not last forever. Give your tractor a jumpstart using your car and booster cables (red on positive, black on negative on both ends). That should tell you if it is a battery problem. Check your charging voltage after you get the tractor started.

How Many Volts Are In A Car Battery? | Advance Auto Parts
Measuring your car battery’s voltage can be a great way to determine how charged your battery might be. The ideal car battery voltage with the engine running is between 13.7 and 14.7V. With the engine off, you should get a reading of 12.6 volts. If the battery isn’t fully charged, it will diminish to 12.4V at 75%, 12V when it’s only operating at 25%, and down to 11.9V when it’s completely discharged.

 

[Wull]

Ok, it’s not the starter. The battery is constantly 12v even when I turn the key. When I connect to the positive on the starter, it's 12. When I turn the key, it drops to almost zero. That connection was loose but that didn’t fix it.
I was able to jump it and get the bucket off of it. That’ll be a big help working on it. It needs to be serviced before I run it again anyways.

When you say “jump it” do you mean used jump cables from another known good battery and connected it up to the battery on the tractor?????? If that worked then your problem is the battery or charging circuit. Get the tractor going again then test the charge rate at the battery, most will be around 13.5-14.5 at idle, give it some revs to see how much it changes, they usually do not exceed 14.5v

Also if the starter was faulty then jumping it from another battery would make no difference, it would still not start. If there was an issue with the wiring, wiring shorted etc it still would not start.

So like above get it started again and check the charge rate. I’ve had batteries in the past that have shown good voltage but lack the ability to crank the engine because they are faulty, it’s the start cranking amps that they really need to power the starter.

 

[lmichael]

Bottom line what everyone is telling you and I totally agree with all of it. Eliminate cables, connections and battery. I tested my starter as well but did not believe my own results LOL. So ended up buying a brand new starter assy. Weird thing when I installed it the machine began starting again. Of course I patted myself on the back too soon LOL. Then I started with the ign switch, and trying to back trace all the micro switches and such. Bottom line after much frustration with how Kubota runs everything, I installed the relay. Everything works as it should now. But, again it was a last resort born by frustration

 

[BruceP]

How is an interlock switch going to cause low voltage at the solenoid actuator terminal?
if all the switches are 'Go' then the starter relay is actuated and Batt+ is switched to the solenoid.
It's pretty much binary.

This is actually the MOST COMMON failure mode for many outdoor equipment. I have encountered this issue my my personal Kubota.

I will assume you know basic ohms-law:

1. One of the safety-switches becomes RESISTIVE when it is closed.
2. This RESISTIVE switch allows battery-voltage to make it to the starter-solenoid.
3. Hence, the starter will CLICK and pull the Bendix mechanism
4. HOWEVER: being RESISTIVE, there is insufficient current available to KEEP the starter engaged
5. END RESULT: Starter clicks but does not crank engine

Many folks have MISdiagnosed a bad (resistive) safety-switch for bad starter because the starter will click. A brand-new starter will do the SAME THING.

As I said above, it is trivial to validate the starter works and isolate which safety-switch is the problem.

1. Jumper battery+ to small terminal on starter to validate starter
2. Use VOLTAGE DROP voltage readings to isolate the resistive switch

Fixing the resistive safety-switch is as simple as soaking it with WD40. (This is what WD40 was originally invented for) Then 'work' the switch about 50 times.

 

[Pawnee]

Fair enough, if you have seen it happen I can't argue with it.
My experience is that switches which are starting to go high resistance quickly fail catastrophically if they are carrying much more than signal current.

If we are discussing a BX2380 then it already has a relay before the solenoid.

 

[Bruh44]

Problem solved. I pulled the positive wire, scrubbed both ends with a wire brush. Used a little electrical grease. Then tightened it back down. It started right up.
Thank you all for your help and suggestions.
Stay tuned for my next idiot tractor moment. I’m about to do all the fluids and grease points so it’s probably not too far off.

 

[country_hick]

Problem solved. I pulled the positive wire, scrubbed both ends with a wire brush. Used a little electrical grease. Then tightened it back down. It started right up.

I would suggest cleaning the negative side also. It is probably about the same.

I think we have all had those moments. Sometimes even those of us who have some experience get frustrated and overlook some simple solutions. I am glad it ended up being a quick simple no cost repair.

 

[torch]

Exactly this. A short can also cause this, not necessarily within the wiring itself but a short within the starter can cause this.

I'm a bit late to the party, but I'd like to point out the error in that logic. Wolfman was bang on when he said the problem had to be in the cable.

If there was a short within the starter but the cable was good, then the voltage drop at the battery end of the cable would be nearly the same as the voltage at the starter motor end of the cable.

A large voltage drop across a conductor means the problem is in the conductor.

A useful way of isolating a poor connection is to meter voltage on either side of the connection rather than fixating on "- to ground, + to the wire". Simply measure voltage from one point in the wiring to another point. With the circuit activated any voltage drop between the points of measurement indicates resistance -- ie: poor connection.

This holds true for grounds too. EG: one lead to the starter motor body, the other to the block or one lead to the block, the other to the battery negative. If you see more than a few tenths of a volt when cranking, you have a poor ground in that segment.

 

[BruceP]

I'm a bit late to the party, but I'd like to point out the error in that logic. Wolfman was bang on when he said the problem had to be in the cable.

If there was a short within the starter but the cable was good, then the voltage drop at the battery end of the cable would be nearly the same as the voltage at the starter motor end of the cable.

A large voltage drop across a conductor means the problem is in the conductor.

A useful way of isolating a poor connection is to meter voltage on either side of the connection rather than fixating on "- to ground, + to the wire". Simply measure voltage from one point in the wiring to another point. With the circuit activated any voltage drop between the points of measurement indicates resistance -- ie: poor connection.

This holds true for grounds too. EG: one lead to the starter motor body, the other to the block or one lead to the block, the other to the battery negative. If you see more than a few tenths of a volt when cranking, you have a poor ground in that segment.

I see you mentioned "VOLTAGE DROP" several times.... this is exactly why I suggested using voltmeter to take "Voltage Drop" measurements and it should take less than 10 minutes to isolate root cause.

I troubleshoot "no crank" issues several times a month on outdoor equipment. "Voltage Drop" measurements quickly isolate where the voltage is getting lost in a circuit. A bad connection or resistive safety-switch cannot hide from "Voltage Drop" measurements with a voltmeter.

 

[torch]

I see you mentioned "VOLTAGE DROP" several times.... this is exactly why I suggested using voltmeter to take "Voltage Drop" measurements and it should take less than 10 minutes to isolate root cause.

Yes you did. And looking back on it, I think we are both guilty of using the term without adequately explaining the concept to the new people. So here goes:

If you google "Ohms Law", you will find an equation such as V=IR. This simply means that the Voltage Drop (V, measured in volts) between the two points measured in an electrical circuit is equal to the Current (I, measured in amps) times the Resistance (R, measured in ohms).

If you have a perfect conductor without any resistance then A amps x 0 ohms = 0 volts.. Similarly, if there is no current flowing then 0 amps x R ohms = 0 volts. There must be some current and some resistance to produce a measurable voltage drop.

Now at this point, some of you are saying "That can't be true -- the meter shows 12 volts when I measure the battery + to -." What you are actually measuring there is potential voltage -- the maximum voltage the battery can supply. The current is miniscule (a few microamps in a digital meter) but the resistance is infinite because the circuit is not yet a closed loop.

Turn something on and the battery voltage will drop. If you were to place a nice fat wrench across the battery terminals, you would see the voltage drop to near 0 (through the sparks, before the wrench turned red and melted) because now the resistance is near 0. Anything x 0 = 0.

EG: Battery voltage is 12.8v with everything off. Turn on the headlights so current flows and the voltage drops to, say, 12.5 volts. The sum of the resistances of the headlights, switch & wires times the current through the circuit equals 12.5 volts (current is always identical at all points in a closed circuit).

If we cranked the engine instead, we might expect to see a battery voltage of, say, 10 volts, because even though the current is much higher, the resistance of the starter motor and those big fat cables is much lower. If we don't see a significant voltage drop it means we have high resistance somewhere.

This was the case in the OP's problem. He hit the key and the battery voltage did not drop. He measured from the starter + terminal to the battery ground and the voltage was near 0. If he had measured the voltage drop between the battery + and the starter while cranking, he would have found the missing 12v -- that is, his meter would show a voltage drop of 12v between the battery and the starter motor -- meaning high resistance in one of the cable, the solenoid or the connections. Metering between either side of the solenoid, he would have found near 0 volts. Metering between the battery + and the solenoid would confirm the voltage drop in the wire and connections was eating up the missing 12 volts.

But let us say he found a voltage drop of 0 between solenoid and battery +. He could then meter between the either side of the solenoid. 12v there means either the solenoid contacts or the switch circuit is at fault -- more on that in a moment. Moving on, check between starter + and the starter case. If it was still near 0, then between the starter case and the engine block. If that was still 0, then odds are he would find 12 v between engine block and battery -- ie bad engine ground or battery connection.

By measuring the voltage drop at all the significant points of the circuit, we can methodically isolate the source of high resistance.

Now, back to the solenoid: The solenoid is actually part of two independent circuits. Obviously it acts as a switch in the starter circuit itself. Burned contacts can be a source of high resistance in that circuit. But it is also part of the key switch circuit, which may include the clutch safety switch, etc. This is were a wiring diagram becomes invaluable, identifying all the various components in the circuit and maybe even their locations.

The solenoid itself should give a nice sharp "click" when the key is turned. If it does but the voltage drop across the solenoid contacts is high then probably the contacts are burnt. If there is no click, or it is an anemic little tick, then we use the same diagnostic process of checking voltage drop through that circuit, starting with the fuse(s), ignition switch, through each safety switch and so on.

Ok, finally: why not just use the meters Ohms scale to measure resistance directly? Well sometimes you can, if it is a low current circuit. But bear in mind that the meter is actually measuring resistance by measuring voltage drop -- the difference is the meter is supplying the potential voltage from it's tiny little AA or 9v battery, meaning it can only supply milliamps of current. Remember that V=IR -- little current means little voltage drop, even if resistance is high. So a poor connection that is capable of passing a tiny current may appear to have low resistance to your meter when in fact it just can't supply the current required under actual conditions.

 

[BruceP]

Condensed version:

• A straight wire is EXPECTED to have 0.000Volts from end-to-end at all times...If a voltage is measured, there is a VOLTAGE DROP across that wire. (bad connections, resistive switch...etc)

--------------------------------------
EXAMPLE:

1. Clipping voltmeter on battery-minus and on starter-case is EXPECTED to to read 0.000 volts at all times.
2. During cranking (when starter clicks) if 3.500 V is measured..... there is a bad connection between battery-minus and starter-case.
3. This also means the starter voltage will be (Battery Voltage) - (3.500V) which may not be enough to crank the engine.

The very same VOLTAGE DROP measurement can be taken between (Battery-Plus) and (Starter positive input).... this will test ALL the safety-switches at once.

 

[Pawnee]

The very same VOLTAGE DROP measurement can be taken between (Battery-Plus) and (Starter positive input).... this will test ALL the safety-switches at once.

That would be true if there was no start relay upstream of the starter solenoid.
Your interlock switch IR drop test on the BX2380 would require measuring between Batt+ and start relay high side.

 

[torch]

That would be true if there was no start relay upstream of the starter solenoid.
Your interlock switch IR drop test on the BX2380 would require measuring between Batt+ and start relay high side.

And again, this is where a wiring diagram is invaluable! <lol>

 

[Wull]

I'm a bit late to the party, but I'd like to point out the error in that logic. Wolfman was bang on when he said the problem had to be in the cable.

If there was a short within the starter but the cable was good, then the voltage drop at the battery end of the cable would be nearly the same as the voltage at the starter motor end of the cable.

A large voltage drop across a conductor means the problem is in the conductor.

A useful way of isolating a poor connection is to meter voltage on either side of the connection rather than fixating on "- to ground, + to the wire". Simply measure voltage from one point in the wiring to another point. With the circuit activated any voltage drop between the points of measurement indicates resistance -- ie: poor connection.

This holds true for grounds too. EG: one lead to the starter motor body, the other to the block or one lead to the block, the other to the battery negative. If you see more than a few tenths of a volt when cranking, you have a poor ground in that segment.

I never said any different, I was meaning that if there was a short within the starter which I’ve had recently with a JD 9009a and a 7700a the voltage drop off was down to literally 1-3 volts, not sure how you read my reply or whether or not I portrayed it in such a way but I was saying that even if the cables showed up good continuity with no shorts then the issue can be within the starter, it depends how you test it.

If you remove the cables from the starter and test them they would test fine if the issue was the starter, if you have the cables connected to the starter and get the voltage drop then this 100% shows the short is within the starter which is the way I tested the two above that I mentioned, two starters ordered fitted and problem solved.

I had a similar problem on a B2150 and tested the starter independently of the wiring and it would work, connected up it wouldn’t, when I removed the main feed cable from the battery it would work just fine, tested that on its own for continuity and it was shot.

 

[torch]

1. One of the safety-switches becomes RESISTIVE when it is closed.
2. This RESISTIVE switch allows battery-voltage to make it to the starter-solenoid.
3. Hence, the starter will CLICK and pull the Bendix mechanism
4. HOWEVER: being RESISTIVE, there is insufficient current available to KEEP the starter engaged
5. END RESULT: Starter clicks but does not crank engine

Close. Very close. But missing one or two points in the middle.

1. One of the safety-switches becomes RESISTIVE when it is closed.
2. This RESISTIVE switch allows battery-voltage to make it to the starter-solenoid.
3. Hence, the starter solenoid will CLICK and pull the Bendix mechanism

4. When the solenoid closes, the starter receives power. The inrush current to the starter motor causes the battery voltage to drop.

5. HOWEVER: being RESISTIVE, the reduced voltage from the battery results in there is insufficient current available to KEEP the starter solenoid engaged
6. END RESULT: Starter solenoid clicks but does not crank engine

 

[torch]

I never said any different, I was meaning that if there was a short within the starter

The logic flaw I referred to was in thinking the starter could be at fault, when existing testing already identified the cable or connections as the culprit.

Battery voltage did not drop when he turned the key. Voltage at the other end of the cable dropped to "almost zero" when he turned the key. Therefore, voltage drop in the cable = 12v. Ergo, problem is the cable or the connections. No need to remove the cable and rig an alternate test. No reason to suspect the starter.

BTW: your embedded video is marked "private" by YouTube and cannot be seen.

 

[Wull]

The logic flaw I referred to was in thinking the starter could be at fault, when existing testing already identified the cable or connections as the culprit.

Battery voltage did not drop when he turned the key. Voltage at the other end of the cable dropped to "almost zero" when he turned the key. Therefore, voltage drop in the cable = 12v. Ergo, problem is the cable or the connections. No need to remove the cable and rig an alternate test. No reason to suspect the starter.

BTW: your embedded video is marked "private" by YouTube and cannot be seen.

See I never read that part, I simply read the bit about possible starter being faulty and seen someone had mentioned voltage drop.
If you test for voltage at the starter, the main 12v feed and have a faulty starter that is shorted out the voltage will fall on its arse. I did this very test when the starter was faulty on the 7700A that I had in and the voltage would drop to something like 1-2v. Starter replaced problem solved.
Like I said previously in this situation you can isolate the starter to test it on its own and test the wiring, which is a test that I had done on a B2150 and that starter checked out, the wiring did not. 12v feed cable replaced, problem solved.

When I did the test on the 7700A i tested the voltage at the battery and starter when trying to start it, the voltage was dropping to 1-2v because of the starter being shorted out. So my logic is just fine, what you then do is test the starter to rule that out then work your way back, it’s a 2 min job to test the starter and if it checks out, check the wiring, if it doesn’t then replace it.
It’s also a 2 min job to check for voltage at the signal switch and constant 12v feed and for continuity between battery and 12v supply cable plus checking that the earth itself is good.

 

[torch]

See I never read that part, I simply read the bit about possible starter being faulty and seen someone had mentioned voltage drop.

Diagnosing something over the internet is difficult. Details are important; the person requesting help must provide them, but the corollary is that those providing help must take account of them too. Please don't take offense, I'm not trying to be critical or to troll you. I'm just trying to help everyone understand and learn for next time.

You are correct that a shorted starter will cause a loss of voltage in the system -- but lack of voltage is not "voltage drop" =-- in fact, it's the opposite. The term "voltage drop" specifically refers to the measurable voltage between two points of a circuit caused by impedance between those two points (in a pure DC circuit impedance is equal to resistance, AC circuits and motors are a little more complicated). The higher the voltage drop, the higher the reading on your meter.
When your starter shorted out, the lack of voltage at the battery was due to the lack of impedance in the starter motor -- virtually all available battery power was being shunted from + to - *. The loss was systemic -- lights dim, horn won't work, clock resets, etc.

As for what to check first:
My own philosopy is to check the cheapest and easiest things first, because a) they don't cost much time or money and b) they are usually the problem anyway. So I would look for voltage drop with a meter (cheap, easy). I would investigate the wiring before the starter (cleaning corrosion: free, replacing wire: cheap, replacing starter motor: expensive).

I would also start at the beginning battery and work forward but either direction will work, provided you proceed in a methodical fashion. Consider the difference in this case: Measured voltage at the battery was 12 volts when it should have been less. So we know immediately that the problem is a lack of current flow and can rule out a shorted starter.

However, if we began at the starter motor terminal the measured voltage between terminal and ground would have been very low, but we would not know if the problem was a lack of current (excessive resistance upstream) or an excess of current (shorted starter exceeding battery capacity).

If we instead measured voltage drop between starter terminal and battery +, we would have seen 12v (ie: voltage drop) and therefore identified the problem as being upstream, ruling out the starter motor. So either direction will work, PROVIDED we are measuring voltage drop between segments of a ciruit rather than constantly referencing all voltage measurements to battery - .

(*note to the Engineers in the audience: according to conventional current flow. Yes, I know the electron flow is opposite, but let's not complicate the discussion any more than we have to.)

 

[Wull]

Problem solved. I pulled the positive wire, scrubbed both ends with a wire brush. Used a little electrical grease. Then tightened it back down. It started right up.
Thank you all for your help and suggestions.
Stay tuned for my next idiot tractor moment. I’m about to do all the fluids and grease points so it’s probably not too far off.

that’s good, I just read the thread back as some of these other replies which were aimed at my posts had me all confused, and sure enough I did read your post right and suggested exactly the above, sometimes folk should just leave well alone.

Ok, it’s not the starter. The battery is constantly 12v even when I turn the key. When I connect to the positive on the starter, it's 12. When I turn the key, it drops to almost zero.

I had read the above and replied with below, and sure enough that’s what was wrong. So my perfect logic and testing method led you down the right path, good find.

If the starter checks out and works, test the main battery feed cable to the starter, the positive cable that goes to the starter. You can test it for continuity but what I like to do as it sometimes might show 12v but falls on its arse when you try and start it is remove that cable from the equation and attach a jump lead, so run a jump lead from the battery positive terminal to the starter