Massey Ferguson 2607H engine dies at random whenever the PTO is engaged

[Nedtrox]

Last spring I purchased a used 2016 Massey Ferguson 2607H with 4 wheel drive and 710 hours on it from a dealership.

The engine dies at random whenever I have the PTO engaged.

Sometimes the engine dies right away when I first engage the PTO and begin to rev it up to the necessary RPM. Other times it would run fine for hours and then all suddenly die. When the engine dies, they are quick kills similar to turning the tractor off with the key.

Furthermore, something new I noticed this winter is that the tachometer wasn’t working correctly at times while the PTO was on. At first I thought it might be the ultra cold weather (10 degrees) affecting it as the tachometer was working fine with the PTO on during the summer. Therefore, I disengaged the PTO and drove the tractor around for a while in the freezing cold and the tachometer was working fine the entire time.

Above is the quick short summary of the issue to get straight to the point.



However, for those who feel my summary is too vague and have many questions I’m going to go into greater detail below and try to give as much information as possible to help diagnose this problem.

This tractor has a Operator Presence Safety Module and according to the logic table on page 61 in the Operator Manual the Safety Module will automatically shut off the engine by turning off the ECUT15 Relay if these 3 conditions are met at the same time:

• The seat switch senses the operator not present in the seat
• The PTO is engaged
• The hand parking brake is NOT engaged

However, the previous owner took the seat switch out and hard wired it so it will always read that the operator is always present regardless if there is anyone in the seat or not. I disconnected the hardness to the seat switch and took it to my ohmmeter to see if the hard wired job the previous owner did had any flaws like a loose connection. With the ohmmeter connected, I moved the wiring around and pulled on it. But the connection is pretty solid, therefore I’m at a loss here.

My next step is to disconnect the PTO safety switch so it always reads the PTO is disengaged and see if this does anything. If not, I'll check the ECUT15 Relay to see if it is starting to go bad.

However, none of this explains why the tachometer wasn't working properly (only while the PTO was on) the last time I used the tractor this winter. On this tractor the speed sensor is electrical and the sensor reads the speed off the flywheel. It’s not a mechanic cable like on the older tractors such as my 30 year old Ford 4630.

Is there a chance this could be a mechanical issue?

When I purchased the tractor it had a clutch issue. The tractor continues to move forward (on level ground of course), when the clutch pedal is fully depressed. I thought a clutch pedal adjustment was all that’s needed to remedy this issue.

Unfortunately, this clutch issue wasn’t resolved after making the adjustment outlined in the operator’s manual. Therefore, the tractor has to be split in half to see what is going on with the clutch. In the meantime, when I have to use the tractor, I always bring the engine to an idle when shifting gears as the issue isn’t that bad at idle speed.

That said, could a bad clutch play any role with the tachometer not working properly or randomly killing the engine while the PTO is engage?

Thought it wouldn’t hurt to ask.

I'm new here and looking forward to any replies. Thanks in advance.

 

[CliffordK]

Your line of thinking is very similar to what I was thinking after reading he first couple of paragraphs.

I'm not sure if the safety switches are normally open or normally closed. However, is it possible that you'd have an intermittent short? Perhaps between the PTO sensor and the panel.

 

[Nedtrox]

Your line of thinking is very similar to what I was thinking after reading he first couple of paragraphs.

I'm not sure if the safety switches are normally open or normally closed. However, is it possible that you'd have an intermittent short? Perhaps between the PTO sensor and the panel.

Indeed, I think you might be right CliffordK. Last night I was studying the Circuit Diagram of the electronics on this tractor and it just dawned on me of how does the engine turn off when you turn the key off. On my old Ford 4630 it's a electric solenoid that cuts the fuel off. But on this tractor I see no such thing on the schematic. Instead, I believe the all done by the ECU (Electronic Control Unit), but I don't know how exactly ECU kills the engine when you turn the key off.

That said, what I do know is that power always has to be present to pin 71 on the ECU. And from what I see there is only 2 ways to remove the power to pin 71 on the ECU: the ignition switch or the ECUT15 Relay that can only be turn on by the Safety Module Unit. As shown below of this screenshot of the schematic with arrows I included to help make it clear.

If I want to be lazy, I guess I could just cut the 'R' wire between the SAFETY MODULE and the ECUT15 relay and be done with it as it will most likely solve my problem. LOL However, I really want to fix the right way.
Therefore, like you said I need to investigate the PTO switch along with the others and see what is tripping up the Safety Module. Lastly, I need to investigate the IG connection on the Alternator. I don't think the Alternator delivers any power out of that connection. I think all the power needed to charge the battery and power all the electronics comes out of the B+ connection. But I could be wrong as I don't know and need to look into it.

 

[JWR]

This is probably the opposite approach (normally I'd say do the electrical and 'easy' part first.) But in this case my guess is that once you solve the clutch problem several of the others will go away or be more obvious. Interactions when things are turning that are not supposed to be turning may get complex, both mechanically and in what is sensed by the various sensors.
Yeah, I think there is a chance that the primary problem is mechanical.

 

[Nedtrox]

Update: I believe I may have solved the tachometer issue or at the minimum a very strong theory of why the tachometer wasn’t working correctly while the PTO was engaged but works normally when the PTO is off. This was an issue that began a month ago this winter.

Whereas there is an electrical speed sensor that reads the speed off the flywheel, this sensor is NOT used by the tachometer nor the digital hour meter. Instead, the tachometer and the digital hour meter receive a square wave signal via the alternator with the frequency being proportional to the engine speed.

I was reading about these BOSCH G1S2 alternators used on the 2600H series tractors in the AGCO shop manual as I was trying to identify the lettering of the 4 terminals on the alternator and what they are used for.

• ‘IG’ (ignition) terminal: receives DC current that powers the internal voltage regulator circuitry used to control the voltage output
• ‘B+’ (battery positive) terminal: delivers DC current to the battery and to the rest of the tractor’s lights and electronics
• ‘WL’ (warning light) terminal: connects to the battery warning light on the instrument panel
• ‘W’ (waveform) terminal: outputs a square wave frequency that is proportional to the engine speed and that is used by the tachometer and the digital hour meter

That said, this is what I think of why I was having issues with the tachometer when the PTO is engaged this winter.

I was using my 3-point snowblower and I do not have a canopy for my tractor. There were many times the wind was blowing the wrong way with myself and the front hood of the tractor getting blasted with snow. As such, I think some of that light powder snow made its way into the side openings of my tractor and got the fan belt wet.

As a result, this caused my fan belt to slip a little causing the square wave frequency from the alternator to be out of sync with the engine speed in turn giving incorrect readings on the tachometer. With the PTO off (and snowblower off) the belt dried and regained its grip in which the tachometer returned to normal.

The fan belt tension is supposed to be checked every 50 hours according to the operator’s manual and I put 40 hours on this tractor since the time I purchased it. Chances are my fan belt could be a little on the loose side and a bit of wet snow was all that was needed to make it slip.

All and all, when I get some time, I need to check the tension on the fan belt and take the tractor out with the PTO on to see if this tachometer issue is resolved with a tighten fan belt.

In the meantime, still trying to figure out what’s killing the engine at random with the PTO on. Still checking safety switches.

 

[Nedtrox]

######### PROBLEMS SOLVED ##########

I found out why the engine dies at random whenever the PTO is engaged and have fixed the issue. Moreover, the issue with the tachometer not reading correctly while the PTO is engaged has been fixed as well.

First, with the tachometer, everything I reported in the previous post was correct. A little tightening of the fan belt was all that was needed to resolve this issue. My tachometer is now reading correctly with the PTO engaged when taking the tractor out today.

Second, what is causing my engine to die at random whenever the PTO is engaged – long story short – it turned out to be the seat safety switch.

The previous owner ripped the seat safety switch out and hard wired this switch forever in the closed position. However, I found out that when this switch is in the closed position, it tells the Safety Module Unit in the tractor that no one is present in the operator's seat. Therefore, by hard wiring this switch closed, the Safety Module Unit will always read that nobody is ever in the seat of the tractor regardless if there is a person in the seat or not.

As I reported in my first post, according to the logic table on page 61 in the Operator Manual the Safety Module will automatically shut off the engine by turning off the ECUT15 Relay if these 3 conditions are met at the same time:

• The seat switch senses the operator not present in the seat
• The PTO is engaged
• The hand parking brake is NOT engaged

The only reason why the engine dies at random instead of every single time once the PTO is engaged is because the hand parking brake was not properly adjusted and is very loose which doesn’t allow it to make good contact with its safety switch. Therefore, the Safety Module reads that the parking brake is engaged whenever it fails to make contact with the switch in turn keeping the engine alive while the PTO is engaged. After enough bumps in the field, eventually it will make contact with the safety switch telling the Safety Module the parking brake is now off and then it kills the engine.

Notwithstanding, I unplugged the seat safety switch from its connector to the main wire harness as this was all that was needed to hard wired the seat switch forever in the open position so the Safety Module will read that there is always someone present in the seat regardless if there is a physical person in the seat or not.

Afterwards, I took the tractor out today, running it with its PTO on. I also turn the PTO off and then back on multiple times. Needless to say, the engine never died once. I think it’s safe to say I resolved the issue. If not, I'll return here and post any new issues.

In the meantime here as some of my notes when testing all the safety switches on this tractor:

• When the PTO is off, its safety switch is in the closed position
• When the Shuttle Lever is in Neutral position, its safety switch is in the closed position
• When the Hand Parking Brake is engaged, its safety switch is in the closed position. However, for some reason this safety switch has 4 plug-in terminals in a square layout. The left and right terminals are the ones used. If the front and back terminals are used everything is inverted. Therefore, using the front and back terminals, once the Hand Parking Brake is engaged, its safety switch is now in the open position. Regardless, it is the closed position that tells the Safety Module that the Parking Brake is engaged.
• When the operator is in the seat, the safety switch is in the open position.

. .