question Zetor 3340 Wiring Fault/ Starting Problem

ZeterBeater · Mar 7, 2024

Hello, I recently picked up a 3340 and it started and ran great everyday until 4 days in, after a rain. Now it does not want to start/turn over. I get an occasional click at the starter but nothing more with standard starting. I can hookup cables to my solenoid and get it to turn over but only a few times, where as the first time I started it (battery was almost dead) I was able to start it with cables like normal (turned over easy).

I am probably gong to pull the starter and solenoid to bench test but I think my issue is in the wiring. THERE ARE A LOT OF WIRES, LOL.

Can anyone advise a basic process here to eliminate what could be causing the key and button to have almost no effect on starting? Again, randomly I'll get one click at the starter and nothing more. It has been a few days now without rain and still won't start.

Symptoms as of now:
1) lights don't work when I turn the key, but they did before.
2) I pulled all fuses but the bottom red wire one with no help
3) The start button and power through the ignition test good.
4) When all fuses and key are in I get power on the left side of all but one of the fuses but also show grounds on almost all? That doesn't seem right...
5) Quite a few times my power is 12+v at the solenoid top bar, but once I try to start the tractor is drops to around 11v. But at the battery I still show 12+v.

I think that's all I got for now. Any help is appreciated.

ZeterBeater · Mar 8, 2024

Was really hoping for some help today but I did make some progress. I pulled the starter and confirmed it works (still can't get all the screws back in, what a nightmare!) I discovered that if I ground the starter (basically to the bolt that hold the starter on the tractor) straight to the battery it works great but if not I only get that random weak click. Is there supposed to be a ground wire to the starter or solenoid because as of now there is not, to my knowledge.

Joachim · Mar 8, 2024

ZeterBeater said:
I think my issue is in the wiring. THERE ARE A LOT OF WIRES, LOL.

Any pictures for a better understandig for us?

ZeterBeater said:
Can anyone advise a basic process here to eliminate what could be causing the key and button to have almost no effect on starting? Again, randomly I'll get one click at the starter and nothing more. It has been a few days now without rain and still won't start.

Sounds to me as if the wiring and/or plugs and/or switches are defective and/or corroded and so there isn't enough power getting to the starter.

You have to approach it systematically and not just try anything at some point. You should also take a few photos so we can SEE what the current condition is.
(is the tractor always outside?)

1. Visually check all cables, plugs and switches to see whether they are OK or damaged/corroded
2. Test the battery (measure the voltage and connect a battery tester to check whether the battery is still OK)
3. If the cables/switches are OK, then measure the voltage once when the start button is pressed (directly on the starter!)
If the voltage drops sharply from 12.4 V, then the starter is defective or there is something wrong with your wiring.

You can remove the start button, clean the contacts, then screw on the switch and also clean the contacts in the switch.
The same applies to all plugs and connections, especially the ground connections.

ZeterBeater said:
1) lights don't work when I turn the key, but they did before.

Checked the fuses and the connections of the cables to the fuses?

ZeterBeater said:
The start button and power through the ignition test good

What exactly does that mean, how did you check it? Even a bad contact or switch can still let the voltage through WITHOUT load. But if a load (A) is added, the voltage can drop and then nothing works.
Therefore, don't just turn the switch on and check continuity, but also test it under load!

ZeterBeater said:
When all fuses and key are in I get power on the left side of all but one of the fuses but also show grounds on almost all? That doesn't seem right...

pictures please...

ZeterBeater said:
Quite a few times my power is 12+v at the solenoid top bar, but once I try to start the tractor is drops to around 11v. But at the battery I still show 12+v.

There you go - exactly what I just wrote before. Either bad ground or a short to ground or simply bad contacts. Especially when electrics get wet, it can be even worse.

ZeterBeater said:
(still can't get all the screws back in, what a nightmare!)

Why???

ZeterBeater said:
Was really hoping for some help today but I did make some progress. I pulled the starter and confirmed it works (still can't get all the screws back in, what a nightmare!) I discovered that if I ground the starter (basically to the bolt that hold the starter on the tractor) straight to the battery it works great but if not I only get that random weak click. Is there supposed to be a ground wire to the starter or solenoid because as of now there is not, to my knowledge.

And again I seem to be right...

Again - first check all cables and connections starting from the battery. Especially the ground connection from minus to the vehicle frame because this is where the starter gets ground. The flange of the starter and the opposite side on the clutch bell must also be free of paint and rust/dirt so that the starter has enough mass via its flange.
Of course, all 3 screws should be tightened tightly.

So now please show me photos...

ZeterBeater · Mar 10, 2024

Joachim said:
Any pictures for a better understandig for us?

Sounds to me as if the wiring and/or plugs and/or switches are defective and/or corroded and so there isn't enough power getting to the starter.

You have to approach it systematically and not just try anything at some point. You should also take a few photos so we can SEE what the current condition is.
(is the tractor always outside?)

1. Visually check all cables, plugs and switches to see whether they are OK or damaged/corroded
2. Test the battery (measure the voltage and connect a battery tester to check whether the battery is still OK)
3. If the cables/switches are OK, then measure the voltage once when the start button is pressed (directly on the starter!)
If the voltage drops sharply from 12.4 V, then the starter is defective or there is something wrong with your wiring.

You can remove the start button, clean the contacts, then screw on the switch and also clean the contacts in the switch.
The same applies to all plugs and connections, especially the ground connections.

Checked the fuses and the connections of the cables to the fuses?

What exactly does that mean, how did you check it? Even a bad contact or switch can still let the voltage through WITHOUT load. But if a load (A) is added, the voltage can drop and then nothing works.
Therefore, don't just turn the switch on and check continuity, but also test it under load!

pictures please...

There you go - exactly what I just wrote before. Either bad ground or a short to ground or simply bad contacts. Especially when electrics get wet, it can be even worse.

Why???

And again I seem to be right...

Again - first check all cables and connections starting from the battery. Especially the ground connection from minus to the vehicle frame because this is where the starter gets ground. The flange of the starter and the opposite side on the clutch bell must also be free of paint and rust/dirt so that the starter has enough mass via its flange.
Of course, all 3 screws should be tightened tightly.

So now please show me photos...

Evening and thanks for the reply. As I mentioned I did trace out quite a few things however in my inexperience, while I did confirm a good ground to block on a lot of things, I apparently did not confirm a good ground direct from battery to frame/block and that was the issue. The battery goes to a bolt THEN to the frame and it was not connecting at the bolt. I went straight to engine block and VOILA it started up for the first time in many days!!

Some of the symptoms were pretty wild like sparking if I jumped the battery negative to frame with cables and how my starter signal wire would go from 12.6v to like .11v+- when I would try to start it. I learned a good amount troubleshooting all this, silly it was so simple.

Joachim · Mar 10, 2024

Thats the electrical magic. Energy float physicaly from - minus (Ground) to + plus and so its realy importand to have a good ground connection from battery minus to chassis and from chassis to the cab.

Robertzetor3340 · Mar 14, 2024

Glad you stuck to checking it out and found where the trouble was.

question Zetor 3340 Wiring Fault/ Starting Problem

ZeterBeater

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Joachim

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question Zetor 3340 Wiring Fault/ Starting Problem

ZeterBeater

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