Main switch head scratchers!!!

[knightgang]

I took the starter for my L2950 to a shop today to rebuild it. I also ordered a new main ignition switch just in case that is part of my issue with my no start and bad starter.

In the meantime, I pulled the service manual to test my existing switch. The resistance test (ohms test) shows that everything appears good.

However, when we applied 12vdc to the switch from a voltage test supply, we could not read any voltage from any of the other pins regardless of key position. We thought this was odd and assumed that maybe while we had volts, there may not have been enough amps. (Not that that should have mattered)

Anyway, so I get home, do another test of the rebuilt starter on the bench and it is good. So I put the fully charged battery in the tractor and plug in the existing key switch. The service manual does not say it but I assume the black/red stripe wire is ground (it ohmed out that way anyway) and I have 12vdc from the B terminal (battery) to ground, but I also have 12vdc from terminal B to all other terminals at any time regardless of key position. However, when you turn the key to AC position, the fuel solenoid opens up, but I get no lights on the dash and no action from the starter in the start position.

I am going to test the new keyswitch tomorrow with the test voltage supply and see if it read differently then the existing switch.

The rebuild shop said that the solenoid in the starter was stuck closed and I think that it may have burned up the switch.

I will be doing more troubleshooting later, checking all fuses and relays, etc. I am hoping that the rebuilt starter and the new keyswitch gets this tractor back in service.

 

[North Idaho Wolfman]

The service manual does not say it but I assume the black/red stripe wire is ground (it ohmed out that way anyway) and I have 12vdc from the B terminal (battery) to ground, but I also have 12vdc from terminal B to all other terminals at any time regardless of key position. However, when you turn the key to AC position, the fuel solenoid opens up, but I get no lights on the dash and no action from the starter in the start position.

I am going to test the new keyswitch tomorrow with the test voltage supply and see if it read differently then the existing switch.

The rebuild shop said that the solenoid in the starter was stuck closed and I think that it may have burned up the switch.

I will be doing more troubleshooting later, checking all fuses and relays, etc. I am hoping that the rebuilt starter and the new keyswitch gets this tractor back in service.

Black Red stripe goes through the switch on the shuttle then through the switch on the PTO then to the start relay, It is NOT ground! It's the start signal that triggers the relay to give power to the starter.

If I'm understanding right, you need to test / replace the start relay, as that is why it burned out the starter because it kept powering the starter after the tractor started.

 

[knightgang]

The tractor never started, it ever turned over. I am not denying that relay may be bad, but why would I have 12vdc from terminal B to every other terminal with the key in off position?


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[Trent]

The tractor never started, it ever turned over. I am not denying that relay may be bad, but why would I have 12vdc from terminal B to every other terminal with the key in off position?


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B+<----------volt meter--------->any working solenoid, relay, light -----ground

The above sketch should show 12VDC on the meter - (with key off). Voltage should go to 0 only when key is on or in start position. The meter is getting it's negative side through any working solenoid, relay, light.

Voltage testing might make more sense keeping the negative lead grounded to tractor.

Are there schematics available? I can't imagine doing this without one.

Trent

 

[knightgang]

So, as of now, I have done some more trouble shooting and determined that the keyswitch is good. I realized I was testing it incorrectly yesterday. With +12vdc on the B terminal and the key in the AC position you should get +12vdc from the AC terminal to ground. I have tested all positions and they are functioning correctly.

Additionally, I have tested both the Timer Relay and the Starter Relay and both appear to be functioning properly.

I guess I have been overthinking this bad starter deal because of the fact that I was welding on this tractor without disconnecting the battery. I was welding on the end lift arms with a good ground connection on the arm 6" from the weld site. When the tractor would not crank afterwards and I discovered the bad starter, I have been paranoid about any electrical issue I would find.

I guess the best thing to do at this point is to put everything back together and turn the key and see what happens.

I have a starter that works on the bench, I have a keys witch that the functions test properly and I have functioning relays. I have already turned the engine over by hand so I know the old tale about locking up a motor did not happen. Unless there is a problem with a safety switch somewhere or a bad wire (which I would have thought would take out a fuse or a relay first, then there should be no issue with it cranking up.

Unless there is something else that I should worry about, please let me know, otherwise everyone wish me luck and we will see how it goes.

 

[knightgang]

Because I hate reading posts on forums of issues and the OP never coming back and posting a resolution to the issue, here it is.

Turns out the keys witch was not the problem, nor any of the relays...

After putting everything back together with the rebuilt starter, I have the same do nothing key switch click. The battery had been on charge ever since this started, but I needed to rule it out as an issue. I took it to Oreilly's for a test in the big tester and it determined that it needed a charge as well (What, it has been charging for 4 days). Well it gave it a high amp 16 minute charge and then tested good. I purchased not battery cables (pos and neg) when home and reassembled. Hit the key and it fired right up like it never missed a beat.

I am not sure what was up with this, but it has worked great and continues to keep a charge. It has been two weeks since the fix and everything is still fine...

 

[olthumpa]

Glad it worked out for you!

 

[ShaunRH]

I thought the standard for tractors was that the body of the key switch was 'ground', all inside reachable terminals are V+ in or out, no ground links at all. So this is confusing to me, switches should only switch to ground if they are on the ground side of the circuit... or at least that's what I thought... am I missing something?

 

[knightgang]

The way I look at it is that the key switch is just that, a switch. It directs the +12vdc current to the pos side of a circuit or set of circuits (electrical components) that they themselves are attached to ground. The switch itself is a current direction and pass through device, no actual ground. Current in and current out...

 

[Tooljunkie]

Battery cables and their connections are the biggest overlooked part of troubleshooting a no start/no crank condition. Just sayin.....

 

[knightgang]

Yeah, rub it in... Thanks.

But I do agree and sometimes the best of us overlook the simple things


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