B7100hst suddenly won’t crank or start?

[Lencho]

Looking for troubleshooting sequence. My B7100hst was starting and running fine yesterday. Today it won’t even turn over.
I checked battery voltage and it is at 12.5V, terminals are clean. I next checked the clutch safety switch and it has continuity when depressed. I checked the fuses on the ignition switch and all are good. Still no crank.
One odd thing is that when I turn the key left for glow plugs the hour meter does not advance. Turning the key right nothing happens - no starter motor turning.
What should I check next?

 

[fried1765]

Looking for troubleshooting sequence. My B7100hst was starting and running fine yesterday. Today it won’t even turn over.
I checked battery voltage and it is at 12.5V, terminals are clean. I next checked the clutch safety switch and it has continuity when depressed. I checked the fuses on the ignition switch and all are good. Still no crank.
One odd thing is that when I turn the key left for glow plugs the hour meter does not advance. Turning the key right nothing happens - no starter motor turning.
What should I check next?

39+ year old tractor....
Internally corroded battery cables.
Replace both positive and negative cables!
Get best quality cables available!

 

[GreensvilleJay]

I'll second that ! 'hollow' battery cables, greenyblue inside ??
Easy test...
grab a 2nd battery and jumper cables, connect -ve onto frame close to starter, zap starter with +12 cable...
I'm guessing it'll spin.....

 

[Lencho]

Ok, I’ll try that next. Thanks!

 

[North Idaho Wolfman]

Do you have you a test light, on these old tractors it's the simple things.
Find out where your getting power and where your not.

 

[85Hokie]

Take the two leads AT the clutch safety switch and place together = I had to do this when I bought my second B7100 - the clutch would not close the circuit well enough - see if this changes anything

 

[Lencho]

Do you have you a test light, on these old tractors it's the simple things.
Find out where your getting power and where your not.

Good advice, I checked the ground first and 12V to ground. Then I checked the power to the starter, 12V there as well. Next I loosened the key switch and found only 10.5V at terminal 50 and 10.7V at the starter. I jumped the solenoid to the battery and got a loud “click” but no crank. I unscrewed and cleaned all the switch terminals with sandpaper and the battery and chassis ground (under the dash by the steering box) As well.
My battery had 12.5V but needed some DI water. I am happy to report that after cleaning the connections it started.
I don’t see 20ohm resistance at the glow plug indicator - I get only 3.5 ohm- so should I replace that part?

 

[Lencho]

PS, I found a helpful video on starter troubleshootin:

I learned to check the voltage drop on the ground and positive sides of the circuit.
after cleaning mine were 0.1 and 0.0V.

 

[North Idaho Wolfman]

Good advice, I checked the ground first and 12V to ground. Then I checked the power to the starter, 12V there as well. Next I loosened the key switch and found only 10.5V at terminal 50 and 10.7V at the starter. I jumped the solenoid to the battery and got a loud “click” but no crank. I unscrewed and cleaned all the switch terminals with sandpaper and the battery and chassis ground (under the dash by the steering box) As well.
My battery had 12.5V but needed some DI water. I am happy to report that after cleaning the connections it started.
I don’t see 20ohm resistance at the glow plug indicator - I get only 3.5 ohm- so should I replace that part?

If you jump the solenoid terminal to the battery wire terminal below it and only get a loud click, you have a dead starter!

 

[Lencho]

Follow up post - after cleaning and checking the circuits it was still not starting at times. I think the problem was my battery. It had 12.5 volts but not enough amps. I could jump start it so I figure the circuits are OK. My past experience with failing batteries they haven’t been up to full voltage so this fooled me.
I replaced the battery and have had no more problems.

In retrospect, NIW was spot on - check the simple things!

I don’t have an amp meter, just a multimeter. How do you folks check amperage on a battery? What measurement indicates it is failing?
This was a new battery in 2017 so I knew It was getting old, but the 12.5V made me think it was good.

 

[North Idaho Wolfman]

I have a digital batter amp tester now to test them, but before that, I just took them to the local auto parts store and they would test it.