Ford 6640 PTO Short

[bsbjmu]

Looking for some advice on my Ford 6640. Everytime I engage the PTO switch, it works for a second and the blows the fuse. We tried replacing the switch and this did not work. We have check most of the wiring pretty good but cannot find a the short. Any suggestions on any other areas that we should be checking for this problem?

 

[whodat526]

check the solenoid on the rear end housing that engages the pto

 

[bsbjmu]

Thanks for the advice. I have attached a picture of a PTO (similiar) to mine. To get to this solenoid, would I need to take off the plate (circled on the attached picture) to do this?

 

[whodat526]

no the the soleniod is on the left side of the rear axle housing inside but the wires should stick out of the side off the housing in front of the axle housings u must pull the lift top to get to the soleniod if i remember right

 

[Jackfr]

Check the blue "safety" relay in the fuse/relay cabinet on the right of the dash before you get into rear end. We were having the same problem with our 6640 and bypassed the safety relay. It works fine now. The safety relay senses alt power to keep power going to the pto solenoid so if the tractor stalls or is shut off with pto on you have to cycle the switch to get pto to work again when it is restarted. The relay must of shorted internally on ours causing the fuses to keep blowing. What you must remember is with this relay bypassed the pto will remain engaged if you stall or shut off the tractor and then restart it.

 

[aggalise]

Check the blue "safety" relay in the fuse/relay cabinet on the right of the dash before you get into rear end. We were having the same problem with our 6640 and bypassed the safety relay. It works fine now. The safety relay senses alt power to keep power going to the pto solenoid so if the tractor stalls or is shut off with pto on you have to cycle the switch to get pto to work again when it is restarted. The relay must of shorted internally on ours causing the fuses to keep blowing. What you must remember is with this relay bypassed the pto will remain engaged if you stall or shut off the tractor and then restart it.

have same problem would like to know how to bypass safty relay' appreciate any help. aggalise

 

[aggalise]

pto on 7740 ford sle will only engage after 15 minutes engine running, then runs for couple of hours, works perfect, then stops for the day. next day same result. any advice.

 

[Jackfr]

Here's some pictures on how we by passed ours with an inline fuse. it's been working fine now for over 4 years. Just remember If you leave the switch on when you shut off or stall the tractor the pto is on when you restart the tractor.

 

[aggalise]

Thanks for the pictures, looks like one end of jumper goes in the center hot hole. Its not clear to me which hole the other end goes in.
We have not had this tractor long and it came with this problem.
We appriciate your helpful response.

 

[Jackfr]

We used the middle and bottom slot on our 6640 Sorry picture isn't clear enough.

 

[Robert Mader]

Check the blue "safety" relay in the fuse/relay cabinet on the right of the dash before you get into rear end. We were having the same problem with our 6640 and bypassed the safety relay. It works fine now. The safety relay senses alt power to keep power going to the pto solenoid so if the tractor stalls or is shut off with pto on you have to cycle the switch to get pto to work again when it is restarted. The relay must of shorted internally on ours causing the fuses to keep blowing. What you must remember is with this relay bypassed the pto will remain engaged if you stall or shut off the tractor and then restart it.

Hi , I have a 96 / 6640 and have the same problem , mine won't blow the fuse , but will run for two hours , or 5 min. no rhyme nor reason . I can restart the " new " switch I replaced and may shut right down or may run for hours ... Can the Safety switch be replaced ? and do your think this s the same problem where the fuse does not blow ??

 

[Robert Mader]

Hi did you get yours to work this way and if so does it go right back to the pto switch ?? any help would be great ... No one in my part of Canada seems to know anything about these tractors .. Thank you

 

[Jackfr]

Hi

Once we removed and bypassed Safety relay (in the pictures above)in our 1992 6640 the pto works fine turning on and off with the pto switch now. I think all the relay is for is so the pto won't restart if you shut off the tractor without shutting off the pto switch and then restart the tractor. We put the fuse inline to further protect the circuit, but be aware the pto will turn on when you restart the tractor if you leave the pto switch in the on position. We also had intermittent pto before removing and bypassing the relay. This intermittent problem could have been caused by a failing safety relay or as one person informed me possibly a bad or failing alternator as he said the relay senses if the engine is running by a sensing wire from the alternator. Our alternator totally failed and we replaced it a few months after doing the bypass but we left the bypass in place.

 

[Kent woods]

Looking for some advice on my Ford 6640. Everytime I engage the PTO switch, it works for a second and the blows the fuse. We tried replacing the switch and this did not work. We have check most of the wiring pretty good but cannot find a the short. Any suggestions on any other areas that we should be checking for this problem?