JD 318 Engine dies when I unplug the front PTO connector
Results 1 to 10 of 10
Like Tree9Likes
  • 2 Post By DWSchwefel
  • 3 Post By martincom
  • 1 Post By Chuckv
  • 1 Post By martincom
  • 2 Post By DWSchwefel

Thread: JD 318 Engine dies when I unplug the front PTO connector

  1. Top | #1

    Join Date
    Jan 2016
    Last Online
    05-14-2019 @ 09:28 PM
    Location
    Deep South
    Posts
    17
    Thanks
    9
    Thanked 0 Times in 0 Posts

    JD 318 Engine dies when I unplug the front PTO connector

    I must have an electrical short somewhere. If I unplug the front PTO connector, forward of the running engine, the engine will die. The front PTO switch will not start the mower/PTO clutch. This 318 had a rear PTO, I removed it an put it on my JD430, along with the switch. I jumped the old plug, as indicated in the wiring diagram for a single PTO. The seat switch is bypassed. This 318 was a basket case when I bought it ($50) It ran great for one year, then I bought the JD430 diesel. I have not ran the 318 for two years/since I removed the the rear PTO unit and the rear PTO switch.

    If anyone has had this problem, please chime in.

    I know my way around with a digital multimeter. I will look for voltage, I will check one wire against another. I will check continuity with ground. I will let you know what I find. I also have the service manual.


    Thanks, DaveS
    BigJim55 and KennyP like this.

  2. Remove Advertisements
    GreenTractorTalk.com
    Advertisements
     

  3. Top | #2
    martincom's Avatar
    Join Date
    Jan 2017
    Last Online
    Yesterday @ 11:03 PM
    Location
    Brainerd, MN
    Posts
    1,524
    Thanks
    18
    Thanked 293 Times in 221 Posts
    If you have and can attach the wiring diagram, I'd be glad to review it for you and make some suggestions as where to look. I have 40 years of experience in electronics. My first guess is that you have open ground some where and the system is finding a ground path through the PTO circuit.
    2017 1025R TLB & 2017 1025R FEL
    2*54 Mower Decks w/Independent Lift
    2*47 Snow Blowers
    2*Cozy Cab
    2*Heavy Hitch Receiver Hitch w/Dual Suitcase Weight Brackets, Storage Cart, & 1*Front Suitcase Weight Bracket
    50" Wicked Root Grapple
    Land Pride LR1560 Land Rake w/ wide gauge wheels & plow blade
    BXpanded Backhoe Dolly
    MCS20 Leaf/clippings hopper
    647 Tiller
    2001 455 AWS & 1999 455 AWS--Both Sold

  4. Top | #3

    Join Date
    Mar 2018
    Last Online
    Yesterday @ 04:46 PM
    Location
    Collinsville, OK
    Posts
    180
    Thanks
    44
    Thanked 33 Times in 20 Posts
    Here's a pic of the wiring diagram.
    Click image for larger version. 

Name:	318-420 wiring.jpg 
Views:	10 
Size:	357.7 KB 
ID:	685282
    VietNam Vet, 68-69
    68 Mower
    '74 112 Tractor
    '86 316 Tractor (361703)
    '89 265 Tractor (597403)
    F725 Front Mow (032048)

  5. Remove Advertisements
    GreenTractorTalk.com
    Advertisements
     

  6. Top | #4
    martincom's Avatar
    Join Date
    Jan 2017
    Last Online
    Yesterday @ 11:03 PM
    Location
    Brainerd, MN
    Posts
    1,524
    Thanks
    18
    Thanked 293 Times in 221 Posts
    At the bottom of the wiring diagram, you'll see a "grounding eyelet" and just to the right of that a "1" in octagon box. This is the tie point for all the component ground wires also identified with a "1" in an octagon box. I'm going to guess that someone has changed the front PTO wiring and its ground wire no longer runs to this tie point, but is attached to the frame or engine. I'm going to further guess there is an issue at this grounding eyelet, or the tie point depicted to the right of it, whereas it is not making a ground connection or a poor one. Does the front PTO light illuminate even when the switch is off and the tractor running? If so, that would confirm the poor ground connection at a near the grounding eyelet. So that is where I would start.
    Ray_PA, KennyP and 1010 like this.
    2017 1025R TLB & 2017 1025R FEL
    2*54 Mower Decks w/Independent Lift
    2*47 Snow Blowers
    2*Cozy Cab
    2*Heavy Hitch Receiver Hitch w/Dual Suitcase Weight Brackets, Storage Cart, & 1*Front Suitcase Weight Bracket
    50" Wicked Root Grapple
    Land Pride LR1560 Land Rake w/ wide gauge wheels & plow blade
    BXpanded Backhoe Dolly
    MCS20 Leaf/clippings hopper
    647 Tiller
    2001 455 AWS & 1999 455 AWS--Both Sold

  7. The Following User Says Thank You to martincom For This Useful Post:

    KennyP (05-10-2019)

  8. Top | #5
    Chuckv's Avatar
    Join Date
    Apr 2013
    Last Online
    Yesterday @ 03:39 PM
    Location
    Pacific Northwest
    Posts
    1,435
    Thanks
    10
    Thanked 391 Times in 313 Posts
    Dave,

    Is this a new symptom on a tractor you have had working properly for some time, or is this a new-to-you tractor that you are trying to sort out from potential prior owner harness hacking? If the latter it sounds like the two harness plugs on the PTO switch are on the wrong side and need to be swapped back. Here is the illustration from the TM1590 manual showing the proper orientations. Note that the harness socket with three wires total (two wires in one connection...) needs to be at the outer side of the switch.

    Click image for larger version. 

Name:	PTO connections.JPG 
Views:	58 
Size:	24.2 KB 
ID:	685320

    Here is a somewhat better schematic of the wiring in the area of the PTO switch from that manual as well.

    Click image for larger version. 

Name:	PTO schematic for 318.JPG 
Views:	58 
Size:	49.5 KB 
ID:	685322

    ...and here are some excerpts of how to test/verify the switch and wiring...

    Click image for larger version. 

Name:	PTO switch testing.jpg 
Views:	4 
Size:	170.4 KB 
ID:	685324

    Hope these help.

    Chuck
    KennyP likes this.

  9. Top | #6

    Join Date
    Jan 2016
    Last Online
    05-14-2019 @ 09:28 PM
    Location
    Deep South
    Posts
    17
    Thanks
    9
    Thanked 0 Times in 0 Posts

    318 dies...........responses

    Great. Lots of responses. Thanks.

    I will try to respond, I may not answer in sequence though.

    The 318 did run and operate properly, for one summer, before I removed the rear PTO. FYI......there are at least three wire nuts that tie wires together above the TDCM.

    I do have the JD wiring diagrams available. At this point I have only two good bulbs on the dash sockets. (they are in the oilpressure and the battery holes) I'll pick up a couple more before I start work today. Regarding the "seeking ground" idea.......I was thinking the same thing. The ground wire for the front PTO is attached to the forward side of the engine.

    I do have the three blue wire connector on the outside of the front PTO switch. I ohm'd out the switch, it seems to be ok. I have no continuity between the "three wire" set......when I turn on the switch, I have a closed circuit. On the inside set of contacts.....I have continuity when the switch is off and an open switch when the front PTO is turned to the run position.

    I have the battery out, the tray out, the side cover off. I'm going to make it easy on myself and remove the dash. Its pretty cramped in there.

    I may try an easy fix, just to nail down the seeking ground theory. I will ground the existing hot wire to the PTO, cut this wire at the switch (I can reconnect it later) and run a new wire to the PTO. It should work properly and verify the theory.


    Thanks to all. DaveS

  10. Top | #7
    martincom's Avatar
    Join Date
    Jan 2017
    Last Online
    Yesterday @ 11:03 PM
    Location
    Brainerd, MN
    Posts
    1,524
    Thanks
    18
    Thanked 293 Times in 221 Posts
    Quote Originally Posted by DWSchwefel View Post
    Great. Lots of responses. Thanks.

    I will try to respond, I may not answer in sequence though.

    The 318 did run and operate properly, for one summer, before I removed the rear PTO. FYI......there are at least three wire nuts that tie wires together above the TDCM.

    I do have the JD wiring diagrams available. At this point I have only two good bulbs on the dash sockets. (they are in the oilpressure and the battery holes) I'll pick up a couple more before I start work today. Regarding the "seeking ground" idea.......I was thinking the same thing. The ground wire for the front PTO is attached to the forward side of the engine.

    I do have the three blue wire connector on the outside of the front PTO switch. I ohm'd out the switch, it seems to be ok. I have no continuity between the "three wire" set......when I turn on the switch, I have a closed circuit. On the inside set of contacts.....I have continuity when the switch is off and an open switch when the front PTO is turned to the run position.

    I have the battery out, the tray out, the side cover off. I'm going to make it easy on myself and remove the dash. Its pretty cramped in there.

    I may try an easy fix, just to nail down the seeking ground theory. I will ground the existing hot wire to the PTO, cut this wire at the switch (I can reconnect it later) and run a new wire to the PTO. It should work properly and verify the theory.


    Thanks to all. DaveS
    I wouldn't
    ground the existing hot wire to the PTO
    . Depending on what you have going on, that may result in something burning up.

    With the front PTO unplugged, set your meter for ohms and measure resistance from the black wire connnecting from the PTO indicator lamp to engine ground. (Battery disconnected.) It should be zero or no more than a few ohms. If it reads open or a higher resistance, you have a poor ground connection.

    What I believe is occurring is you have a poor ground connection. As such, the ignition system is seeking a "sneak path" through the PTO indicator lamp and/or the diode across it via the 100 Blk, through the lamp and/or diode, then 751 blu, changing over to 750 blu at the PTO switch (not passing through the switch), to the x25 PTO connector, through the PTO and then to ground on the otherside of the PTO coil as it has been changed to a direct ground connection as you stated in Post #6.
    1010 likes this.
    2017 1025R TLB & 2017 1025R FEL
    2*54 Mower Decks w/Independent Lift
    2*47 Snow Blowers
    2*Cozy Cab
    2*Heavy Hitch Receiver Hitch w/Dual Suitcase Weight Brackets, Storage Cart, & 1*Front Suitcase Weight Bracket
    50" Wicked Root Grapple
    Land Pride LR1560 Land Rake w/ wide gauge wheels & plow blade
    BXpanded Backhoe Dolly
    MCS20 Leaf/clippings hopper
    647 Tiller
    2001 455 AWS & 1999 455 AWS--Both Sold

  11. Top | #8

    Join Date
    Jan 2016
    Last Online
    05-14-2019 @ 09:28 PM
    Location
    Deep South
    Posts
    17
    Thanks
    9
    Thanked 0 Times in 0 Posts

    My Theroy

    Martincom,

    I wasn't able to try my suggested idea. I did read over your post. One thing to note.......I don't have bulbs in either of the PTO indicator lamp sockets. I will get the bulbs tomorrow and run the tests that you suggested. Would the fact that there are no bulbs make a difference to your suggested tests?

    Thanks again,

    DaveS

  12. Top | #9
    martincom's Avatar
    Join Date
    Jan 2017
    Last Online
    Yesterday @ 11:03 PM
    Location
    Brainerd, MN
    Posts
    1,524
    Thanks
    18
    Thanked 293 Times in 221 Posts
    Quote Originally Posted by DWSchwefel View Post
    Martincom,

    I wasn't able to try my suggested idea. I did read over your post. One thing to note.......I don't have bulbs in either of the PTO indicator lamp sockets. I will get the bulbs tomorrow and run the tests that you suggested. Would the fact that there are no bulbs make a difference to your suggested tests?

    Thanks again,

    DaveS
    No, the lamps wouldn't make a difference in the sneak path as the diodes across each lamp would be forward biased, completing the "sneak path". So installing or removing the lamps would not make any difference. You could try disconnecting the PTO lamps at connectors P1 and P2 as wells as the hour meter (if you have one), as it could be another possible sneak path. If it is a ground issue, it shouldn't run at all then. In my opinion, performing the resistance measurements I had set forth in my previous post is simpler and would tell us more.
    2017 1025R TLB & 2017 1025R FEL
    2*54 Mower Decks w/Independent Lift
    2*47 Snow Blowers
    2*Cozy Cab
    2*Heavy Hitch Receiver Hitch w/Dual Suitcase Weight Brackets, Storage Cart, & 1*Front Suitcase Weight Bracket
    50" Wicked Root Grapple
    Land Pride LR1560 Land Rake w/ wide gauge wheels & plow blade
    BXpanded Backhoe Dolly
    MCS20 Leaf/clippings hopper
    647 Tiller
    2001 455 AWS & 1999 455 AWS--Both Sold

  13. Top | #10

    Join Date
    Jan 2016
    Last Online
    05-14-2019 @ 09:28 PM
    Location
    Deep South
    Posts
    17
    Thanks
    9
    Thanked 0 Times in 0 Posts

    Problem Solved.....

    I started checking ground wires, battery disconnected, and PTO disconnected, and wasn't seeing much of any continuity to the ground.

    I then removed the TDC module so that I could get a better look at the wires. I started to look for and follow and tug the black wires. I found that there were three ground wires connected to an eye terminal........hanging in open air, not attached to chassis/ground. It was pretty hard to miss once you started looking.

    I connected them to chassis and voila. All is good.

    Thanks for the detailed guidance.

    DaveS

    JD430
    JD318 and
    SST16

    JD400 Backhoe
    Ford 340 Backhoe
    Massey 165
    JD 450D Dozer (rebuilding engine and transmission)
    IndianaJim and KennyP like this.

  14. Remove Advertisements
    GreenTractorTalk.com
    Advertisements
     

Similar Threads

  1. Shift into L or H engine dies and no PTO
    By dadtoandrew in forum Medium Frame Compact Utility Tractors (MCUT)
    Replies: 22
    Last Post: 01-23-2019, 09:54 PM
  2. 420 front pto wiring connector
    By sroysr in forum Vintage Lawn & Garden Tractors
    Replies: 3
    Last Post: 04-30-2018, 06:13 PM
  3. JD 318 dies when put in gear
    By lilwing500 in forum Vintage Lawn & Garden Tractors
    Replies: 4
    Last Post: 07-13-2013, 08:12 AM
  4. JD 318 dies when put in gear
    By lilwing500 in forum Forum Help & Suggestions
    Replies: 0
    Last Post: 06-25-2013, 02:55 PM
  5. JD 318 dies when deck engaged (cut extremely wet grass when incident occurred)
    By turklefoot in forum Vintage Lawn & Garden Tractors
    Replies: 11
    Last Post: 04-30-2011, 05:03 PM

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •