How to diagnose is PTO Speed sensor is faulty MCCormick MC135

[MC135]

Hi,

PTO will engage for a couple of seconds then stop on my McCormick MC135. I’ve been told it could be the speed sensor but was hoping there was some way to confirm this?

Thanks!

 

[TaKeN]

Alternator belts nice and tight? Any slight bit of slippage and it'll throw the PTO out.

@McCman

 

[Oh Deere]

the dash read out wont work if sensor has gone

 

[case 5140]

ive got an mx120 that dose this with the sprayer on can take 5 go s to get it to work.
Had it on the west dual spreader today worked ok .
whats wrong with it cant trust it?

 

[timmyboy]

Don’t some of them stop if you get off the seat? Or won’t start if you’re not on the seat? Could be a sensor playing up? Just a thought.

 

[njneer]

Think there is a calibration for this , the pto speed signal is matched to the signal coming from alternator which provides the engine speed.
When they get too far apart the pto wont run properly.
There is a jump wire to be put in to a plug under the dash if I recall then you have to set engine revs in stages and measure the hertz reading from alternator and then I cannot remember the rest unfortunately.

 

[MC135]

Fan belt seems to be grand tension wise. Sometimes it’ll run for 5 or ten minutes then stop. Very annoying. Works even when you’re off the seat so safety feature not an issue

 

[Oh Deere]

In your case I would say its the speed sensor but check this by looking at how accurate your dash reading is and does it fluctuate
If the PTO won't start when the tractor is on tick over but will start when the revs are increased then it need calibrating.
You could pull the speed sensor out to find some fillings stuck to the end of it .Quick wipe might fix your problem

 

[MC135]

In your case I would say its the speed sensor but check this by looking at how accurate your dash reading is and does it fluctuate
If the PTO won't start when the tractor is on tick over but will start when the revs are increased then it need calibrating.
You could pull the speed sensor out to find some fillings stuck to the end of it .Quick wipe might fix your problem

The dash reading seems to be reading correctly. PTO starts every time by cuts out after a few seconds on a lot of occasions.

Got set up in the field and was able to spread fertiliser with just a couple of interruptions this morning. It seems that the only way to keep it going is to not touch any gears etc once the PTO is engaged. Picking up a speed sensor after lunch anyway so hopefully that is the problem

 

[ced]

Check for error codes with the green engagement light

 

[njneer]

Found it eventually .
As previously mentioned there is a calibration to marry the engine speed read from the alternator and the rotation speed at the shaft to enable the ecu to identify pto slippage.

 

[timmyboy]

Found it eventually .
As previously mentioned there is a calibration to marry the engine speed read from the alternator and the rotation speed at the shaft to enable the ecu to identify pto slippage.

Top job @njneer . Very handy.

 

[MC135]

Found it eventually .
As previously mentioned there is a calibration to marry the engine speed read from the alternator and the rotation speed at the shaft to enable the ecu to identify pto slippage.

Completed the calibration procedure this evening and the PTO worked fine afterwards. Only tried it a couple of times but hopefully that’s it sorted now.

Thanks for the attachment and all the suggestions!

 

[Liam]

What was the solution in the end? Thanks

 

[Lazy Sod]

Obviously I realised that tractor rev. counters stopped being cable driven from the engine years ago, but I had always assumed that there would be a sensor picking up a pulse from the flywheel. I have never heard of it coming from the alternator. Is this the normal practice these days, or does it vary between different manufacturers? What about cars?

 

[Mursal]

Cars use a flywheel or crankshaft sensor like you say, the alternator seem to be used by only some tractor manufacturers.

 

[v8willy]

ive got an mx120 that dose this with the sprayer on can take 5 go s to get it to work.
Had it on the west dual spreader today worked ok .
whats wrong with it cant trust it?

What revs does it idle at? needs to be around 8/900 rpm for the pto to kick in.

 

[dirtdoctor]

Hi,

PTO will engage for a couple of seconds then stop on my McCormick MC135. I’ve been told it could be the speed sensor but was hoping there was some way to confirm this?

Thanks!

Hi, I no this is an old post but thought it may help someone in the future, I've just had the same problem with a MC 115. Luckily I have a MTX 135 so i changed the speed sensor over and away it went.

 

[Ericrautenbach]

Hi, anyone possibly have the 135 service books electronically?

 

[timmyboy]

I bought one off E Bay sometime ago on disc for both xtx and mtx and find them very useful. Not sure if they are still available but at something like a fiver each might well be worth a gamble.

Hi, anyone possibly have the 135 service books electronically?

Have you got PTO problems @Ericrautenbach ?