40 serries ford sle pto problems

[aggalise]

pto only engages sometimes

 

[agrimax]

Could be faulty pto switch or loose wiring. Check the wires on the alternator are tight and making good connection and is it actually charging good. Belt tight? Also pto control relay in fuse box may need swapped with a known good one. The insulation on the wires going to the pto control valve is known to break down.Can be got at through the round plate on the left side in front of the left trumpet housing.Behind the lower fuel tank(if you have one). Had this on my 8240--the wires were completely bare,internally from the rubber grommet to the valve.

 

[aggalise]

Could be faulty pto switch or loose wiring. Check the wires on the alternator are tight and making good connection and is it actually charging good. Belt tight? Also pto control relay in fuse box may need swapped with a known good one. The insulation on the wires going to the pto control valve is known to break down.Can be got at through the round plate on the left side in front of the left trumpet housing.Behind the lower fuel tank(if you have one). Had this on my 8240--the wires were completely bare,internally from the rubber grommet to the valve.

Thanks for your information.
We changed the PTO module and alternator with new ones. Checked all except checking insulation on wiring. Will do that, now. Do you know if there is a fuse in the fuse panel to control the PTO other than the relay? Just aquired tractor, have no book and nearest dealer is 70 miles away. Thanks again for all your help.

 

[Lincs Lass]

Landlords 7840 sle had this problem couple of weeks back ,,it was a small valve somewhere near the fuel tank ,,ill ask him which bit it was

 

[agrimax]

Don't believe there was a fuse.The wires were touching on mine.Would have expected a fuse to have blown but didn't find one.The wires can be felt through the round plate and were on spade terminals IIRC. A fidgety job but do-able. However,if the pto valve is the problem,the top lid would need removing.

 

[Drillman]

Pop the top off the twisty knob that engages the PTO in the cab and make sure the screw inside is tight.

 

[Nearly]

I'm with agrimax, it's probably the wiring through the side of the gearbox, mine was.
You can check which side of the switch is the problem by popping the switch out and if you apply a 12v feed to the bulb it will engage the pto solenoid. If it is still intermittent it's the wiring.

 

[aggalise]

Don't believe there was a fuse.The wires were touching on mine.Would have expected a fuse to have blown but didn't find one.The wires can be felt through the round plate and were on spade terminals IIRC. A fidgety job but do-able. However,if the pto valve is the problem,the top lid would need removing.

 

[aggalise]

If the wiring is bad, do you tape it or replace it. How did you go about doing yours?

 

[Nearly]

Wires are a pair, 25cm long with rubber grommet in middle. They go through the side of the back end behind the lower plastic diesel tank. Diesel tank can rub on wires etc over the years.
Back left wheel off, slide diesel tank away from tractor, drain back end oil, round steel plate behind tank to remove, insert hand (to elbow) undo spade connectors single handed. Pry old rubber grommet out from outside, withdraw 2 wires. Insert new wires, bit of lube on grommet and use a piece of pipe to tap it home. Reconnect in reverse etc.
buy a cd workshop manual, they're only a few quid. Have fun

 

[aggalise]

I'm with agrimax, it's probably the wiring through the side of the gearbox, mine was.
You can check which side of the switch is the problem by popping the switch out and if you apply a 12v feed to the bulb it will engage the pto solenoid. If it is still intermittent it's the wiring.

 

[aggalise]

The test that you refered to (running hot wire to on/off light) is that to test the internal PTO wiring to the solenoid, or is it to test the on/off switch wiring. Should the tractor engine be running for this test? Also, does this bypass the need for the signal from the alternator to engage the PTO?
We really appreciate all of your help,
Thanks

 

[aggalise]

Pop the top off the twisty knob that engages the PTO in the cab and make sure the screw inside is tight.

 

[aggalise]

Thanks, tried it and it is all right.

 

[Nearly]

The test that you refered to (running hot wire to on/off light) is that to test the internal PTO wiring to the solenoid, or is it to test the on/off switch wiring. Should the tractor engine be running for this test? Also, does this bypass the need for the signal from the alternator to engage the PTO?
We really appreciate all of your help,
Thanks

The test bypasses the alternator, the solenoid, the switch and the fuses. Best make it a fused feed then.
The engine needs to be running to see if the pto turns.

 

[aggalise]

Wires are a pair, 25cm long with rubber grommet in middle. They go through the side of the back end behind the lower plastic diesel tank. Diesel tank can rub on wires etc over the years.
Back left wheel off, slide diesel tank away from tractor, drain back end oil, round steel plate behind tank to remove, insert hand (to elbow) undo spade connectors single handed. Pry old rubber grommet out from outside, withdraw 2 wires. Insert new wires, bit of lube on grommet and use a piece of pipe to tap it home. Reconnect in reverse etc.
buy a cd workshop manual, they're only a few quid. Have fun

 

[aggalise]

Thanks, ordered CD as you suggested. It should come in about 5 days. We found an open spot in the orange wire that was rubbing the transmission case. It was about 4 inches from the conector to the pigtail, before you get to the grommet. We repaired that spot. The wires from the grommet to the pigtail appear to be in good order (Both are black). We tried the live wire to the bulb with a 5 amp fuse in the jumper. The bulb flashed and immediately blew the fuse.
Question: In your opinion, do you think a 5 amp is enough amperage to complete the test? If not, what amperage would you suggest?

 

[Nearly]

The book says the circuit should be fused with 5 amp fuse, you connected to live terminal of bulb?

 

[agrimax]

Just out of curiosity Nearly,is that only a temporary fuse for a test circuit or is there a fuse in the fuse box for the pto? Mine was a prequad and I never found a fuse for the pto but maybe later tractors had one.Unless a relay clicked out,I wondered why nothing melted,or worse,when my wires were touching.

 

[Nearly]

There's a fuse in the fuse box for pto circuit. 5a according to my book, I'm too idle to step outside and have a look.
You've got the basic information, not much more I can help you with, I'm just a muppet.