Below is a bit of advice that works well to help get you on the right path to diagnosing a fault on a tractor. The aim is to identify which system is at fault so you are not wasting time chasing a best guess when it comes to fault finding.
We can split the tractor up into 3 different systems.
System 1- The mechanical system is the nuts and bolts of the tractor. For example, the transmission gears and shafts, bearings, crown wheel, drive damper, drive shafts etc.
System 2- The electrical system. Is just that. Anything electrical or electronic. For example, modules, sensors, solenoid coils, battery, wiring, switches etc.
System 3- The hydraulic system is anything using hydraulic oil. So hydraulic pump, clutch packs, hydro drive units, filters, etc.
If only one system has an obvious fault its easy to diagnose. So, if the wheel has fallen off or the cooling fan bearing has failed it is obviously A mechanical issue and easy to diagnose.
However, if the rear PTO is not turning on, it is a bit more complicated. Is it an electrical issue with a switch or a sensor? Could it be a hydraulic problem with the valve or clutch piston? Or is it a mechanical issue with burnt clutch plates or a snapped shaft inside the transmission?
There are lots of different ways to approach the issue and we have all developed our own personal way to diagnose problems. Sometime things can get a bit confusing if we have jumped around the tractor randomly checking parts. A great approach is to identify which of the tractor systems may be involved. So, for our PTO issue it could be electrical, mechanical, or hydraulic. Where to start?
A great way forward is to find a component where 2 of the systems meet and is easy to get to. A good example may be the PTO solenoid. This would be where the hydraulic and electrical systems meet. Begin testing at the solenoid. This way we can identify if the electrical system is working and if the hydraulic system has pressure.
Following a procedure like this really helps get on the right path. It can be a bit embarrassing and annoying if you spend 3 hours checking the electrical system just to find out the clutch has failed.
Another example could be a transmission speed sensor error. In this case we can begin looking at the electrical and mechanical systems. The point where the 2 systems meet would be at the speed sensor.
I have found following these steps really helps get on the right path. It is not always that easy to trouble shoot issues, but following a basic plan ensures you are looking at the system that has the fault and speeds up the diagnostic process.
If you find that the tests you are doing are starting to contradict previous test results or its just getting confusing. STOP, have a quick break, and go back to the basics. Its amazing how often you find something you missed and suddenly, the problem is located.