IntellDisplay of PTO RPMs Is Not Working

[Chewwy]

The IntellDisplay on my L3240 HST is not indicating the PTOs RPMs. The PTO is operating just fine and I can control its speed with the engine rpms.

The problem has existed sporadically for several years with the display starting to work several minutes after the PTO is engaged. Recently, the display has persistently failed to display the PTOs speed. It just says PTO Off.

It‘s probably a loose connection somewhere. I’m just not sure where to look. The shop manual says either the wiring harness is disconnected or the the engine tachometer sensor is defective. The display still indicates the engine‘s rpms which leads me to believe neither one of these items are the problem.

Has anyone had a similar problem and been able to resolve it?

 

[workinonit]

There is a speed sensor on the PTO shaft that is probably intermittent. Or maybe a wiring problem going to the speed pickup. My 5090 has done the same thing since it was new.

 

[Chewwy]

There is a speed sensor on the PTO shaft that is probably intermittent. Or maybe a wiring problem going to the speed pickup. My 5090 has done the same thing since it was new.

I thought about that but the wiring schematic does NOT show any PTO speed sensor. The service manual indicates the PTO speed indication is derived from the engine tach sensor. The engine tach IS displaying engine RPMs.

 

[workinonit]

So the display is calculating PTO speed form engine RPM? Not a great way to do it but not many years ago we didn't even have PTO speed, we had a hash mark on the tach. Well, if that is actually true and the engine RPM is not malfunctioning when the PTO speed goes away then I would say your display is the issue or the ECU since one of those would be responsible for calculating the PTO RPM.

 

[ptsg]

Must be a bad switch (or wiring to it) for the PTO lever. It's not sending signal to the dashboard that the PTO is on.

 

[workinonit]

Good point. I thought I had read that the PTO was showing on but it was the opposite. That could very well be the issue. If it doesn't know the PTO is on it's probably not going to calculate PTO speed.

 

[Chewwy]

Must be a bad switch (or wiring to it) for the PTO lever. It's not sending signal to the dashboard that the PTO is on.

The switch itself at the PTO lever IS working. That switch turns the PTO on and off and the PTO is engaging and working. The switch has one set of contacts and only two wires.

The wiring connected from this switch is pretty complex and clearly does more that just turn the PTO on and off. It is interconnected with the fuse panel, the display panel, as well as the ECU.

There are lots of good suggestions here but unless you have had this specific problem and have resolved it, it is unlikely they would not have been already considered.

 

[workinonit]

Do you have the tech manual for the tractor? If not you need to get that.

 

[ptsg]

The switch itself at the PTO lever IS working. That switch turns the PTO on and off and the PTO is engaging and working. The switch has one set of contacts and only two wires.

The wiring connected from this switch is pretty complex and clearly does more that just turn the PTO on and off. It is interconnected with the fuse panel, the display panel, as well as the ECU.

There are lots of good suggestions here but unless you have had this specific problem and have resolved it, it is unlikely they would not have been already considered.

The lever uses a cable to actuate the PTO valve directly, so the switch is irrelevant to turn the PTO on or off. The switch sends signal to the dashboard, which is then used to prevent the engine from starting with the PTO engaged and also for the dashboard to know when to display PTO RPM. That's why I mentioned the switch and/or the wiring.

Unless you have the L3240 HST-3 which has a different setup and uses a PTO switch and a solenoid valve to engage the PTO. An electric over hydraulic setup.

 

[Chewwy]

Do you have the tech manual for the tractor? If not you need to get that.

I DO have the service manual. It is of little help. It points to either a failure of the engine tach sensor or wiring harness from the tach sensor. The tach is working fine.

 

[Chewwy]

The lever uses a cable to actuate the PTO valve directly, so the switch is irrelevant to turn the PTO on or off. The switch sends signal to the dashboard, which is then used to prevent the engine from starting with the PTO engaged and also for the dashboard to know when to display PTO RPM. That's why I mentioned the switch and/or the wiring.

Unless you have the L3240 HST-3 which has a different setup and uses a PTO switch and a solenoid valve to engage the PTO. An electric over hydraulic setup.

Thanks!!

I think you have hit the nail on the head. I was unaware the pto is engaged by a cable. The service manual is just not that clear.

After your suggestion, I went digging in the parts manual and found the PTO cable diagram.

 

[dstig1]

Well which version do you have? I know the later ones like mine have a knob that you push and turn to activate the PTO. That knob is electrical only and drives other things like PTSG said to engage the PTO.

Here's something to try: Tractor fully off. Engage your PTO (knob, lever whatever). Step on clutch and try to start the engine. The interlock should prohibit it from starting.