M9540 no starting problem

[Tx Jim]

My friends M9540 won't start. He has cleaned/tightened all battery cable ends. Battery tests 12.5 volts with wire loose from starter solenoid post but volts lower to 6.5 when wiring harness supply wire is attached to large starter solenoid post. Anyone know where can he get a copy of the wiring diagram?
Thanks for any help, Jim

 

[Roadworthy]

I don't think he needs a wiring diagram just yet. Charge the battery and have it load tested. It sounds like high internal resistance in the battery - assuming connectors were clean and tight and the frame connection was as well.

 

[Tx Jim]

He charged battery & attempted to start it with his battery charger attached & set for jump start & nothing happened. He stated he removed starter & had it checked by a qualified starter repairman. Starter passed inspection.

 

[GreensvilleJay]

Was the 'jump start' with charger connected to existing battery or at the starter ?
I suspect 1st, and that usually means bad battery cables.
If you did #2, it should have started as it bypasses the cables.

Since you know starter is good, battery is good , all that's left ARE the battery cables...
How old are the cables ? Ever left out in the rain ?

 

[Henro]

My friends M9540 won't start. He has cleaned/tightened all battery cable ends. Battery tests 12.5 volts with wire loose from starter solenoid post but volts lower to 6.5 when wiring harness supply wire is attached to large starter solenoid post. Anyone know where can he get a copy of the wiring diagram?
Thanks for any help, Jim

First this is a second hand story, and there is a chance something was not communicated perfectly between TX Jim and his friend.

Unloaded the battery measures 12.5 volts, but as soon as the wire from the battery to the starter solenoid is reconnected to the large lug on the solenoid, the battery voltage drops by about 50 percent? This should never happen, as the starter solenoid terminal should be connected to nothing before the solenoid is activated. The battery voltage should remain the same whether the cable is hanging in the air or connected to the solenoid main lug.

Now if AFTER the cable is connected to the starter, the voltage drops AFTER the starter solenoid is energized, this would indicate a bad battery.

So my bet is we need more accurate details before we can do more than just take a wild guess...

Kudos to TX Jim for wanting to help his friend solve the problem.

 

[Mark_BX25D]

Since you know starter is good, battery is good ,

???

I didn't see anything about a battery being good. Did I miss it somewhere? I went back over the thread and looked, but still don't see it.

Unless I missed it somewhere, I'm with Henro; the battery needs to be load tested.

 

[GeoHorn]

A healthy battery should have 12.7 as a minimum. This sounds like bad battery.

 

[Tx Jim]

I agree possible bad battery. . My friend stated last time we talked that he was going to load test the battery in question.

 

[GreensvilleJay]

In 2nd post... He charged battery
Now I'm assuming he did fully charge it and tested to confirm it was a good battery....

 

[Mark_BX25D]

You know what happens when we assume.....

 

[Fordtech86]

With everything hooked up, take the volt meter and put one lead on the positive cable at the battery, take the other lead and put it on the positive post at the starter and see if there is any voltage.

 

[lugbolt]

My friends M9540 won't start. He has cleaned/tightened all battery cable ends. Battery tests 12.5 volts with wire loose from starter solenoid post but volts lower to 6.5 when wiring harness supply wire is attached to large starter solenoid post. Anyone know where can he get a copy of the wiring diagram?
Thanks for any help, Jim

put the wire back on the starter, then take your volt meter and put one probe on the pos battery terminal (the post not the wire or clamp), and the other on the starter. What's your voltmeter read? If less than 0.5v, that's good. Then if you have someone try to crank the engine with your probes still connected, if your reading on the meter is less than 1.0v that's fine. If more than those, your battry cable has an issue.

that's called a voltage drop test. The meter shows how much voltage is dropping through a conductor.

 

[Tx Jim]

Thanks for all replies. I'll email that information to my friend. Thanks again, Jim

 

[GeoHorn]

In 2nd post... He charged battery
Now I'm assuming he did fully charge it and tested to confirm it was a good battery....

I know you know this…but just because someone puts a charger on a battery and the meter on the charger reduces to zero….doesn’t mean that battery has any useful capacity whatsoever.

12.5 volts is not a healthy battery that is “fully charged”. (In fact, 13 volts doesn’t prove the battery has useful capacity. BTDT)

 

[Tx Jim]

My friend located poor connection on slow-blow fuse. Tractor starts when ign switch is turned to start position. Thanks for all replies.

 

[fried1765]

???

I didn't see anything about a battery being good. Did I miss it somewhere? I went back over the thread and looked, but still don't see it.

Unless I missed it somewhere, I'm with Henro; the battery needs to be load tested.

ABSOLUTELY!
Because a battery shows 12+ volts, people automatically assume that the battery is fine.
NOT SO!
The OP needs to help his friend remove the battery, take it to an auto parts store, and have it load tested!
I'll bet that battery is shot!

For everyone here on OTT, if you have more than just a couple of batteries, you really should own a simple carbon pile battery load tester.
The 100 amp testers are under $40, and the 500 amp testers (I have one) are under $80 (Amazon).
A 100 amp load tester will prove condition of an automobile or similar size battery, and with no need to actually remove the battery.

 

[GreensvilleJay]

free and easy load testing....
put 'suspect' battery into another vehicle ( but NOT wife's ride...) and see if it starts and runs fine....

 

[fried1765]

free and easy load testing....
put 'suspect' battery into another vehicle ( but NOT wife's ride...) and see if it starts and runs fine....

I find battery swapping to not be fun!

 

[Tx Jim]

ABSOLUTELY!
Because a battery shows 12+ volts, people automatically assume that the battery is fine.
NOT SO!
The OP needs to help his friend remove the battery, take it to an auto parts store, and have it load tested!
I'll bet that battery is shot!

For everyone here on OTT, if you have more than just a couple of batteries, you really should own a simple carbon pile battery load tester.
The 100 amp testers are under $40, and the 500 amp testers (I have one) are under $80 (Amazon).
A 100 amp load tester will prove condition of an automobile or similar size battery, and with no need to actually remove the battery.

OP is disabled from nerve damage so I can't help my friend remove a battery from a tractor that in post #15 I stated that the no start problem was ""poor connection on slow-blow fuse" not faulty battery.