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915B intermittently won't turn over

9K views 32 replies 7 participants last post by  kbeaag 
#1 · (Edited)
I have a 3 year old 915B that every now and then won't turn over. The hour meter comes on, but other than that, it's like the battery cable is disconnected because the machine is as dead as can be. After the usual ritual of fiddling around with the PTO switch, popping the seat up and looking at the battery, putting the seat back down, looking skywards to see if rain is on the way, getting a fresh beer... and trying a few more times, it will start. But, I know that my luck is going to run out one of these days.

It seems like some kind of electrical issue, as if one of the safety switches might be malfunctioning. Is there a history of specific electrical problems or a trouble shooting procedure that I can focus my troubleshooting efforts on? Is there an easy way to bypass* the safety switches for testing purposes?I don't want to send it to the dealer unless the problem is chronic and they can observe it. On the other hand, I don't want a failure that results in 2-3 weeks of down time while I wait for the dealer to get to it.

I forgot to mention - engaging the PTO will cause something toward the back of the machine to click.

*I'm not one to permanently bypass safety switches, but short of replacing the switches, I don't know of any other way to troubleshoot them.
 
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#2 ·
Looking at the battery won’t help much. First thing to do is remove the battery terminals, clean them (cable ends and terminals themselves), and reinstall. 9 times out of 10 this solves issues like what you are seeing.

If that doesn’t help then it would be time for further diagnosis.

Product Metal Steel Pipe Cylinder
 
#3 ·
Looking at the battery won’t help much. First thing to do is remove the battery terminals, clean them (cable ends and terminals themselves), and reinstall. 9 times out of 10 this solves issues like what you are seeing.

If that doesn’t help then it would be time for further diagnosis.
Thanks, yes - I have done that, and even gone so far as to replace the battery. Terminals are clean as new.
 
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#4 ·
Replace your PTO switch. It’s a common issue and considered a “wear item.” To get you by, you can wiggle and cycle the switch until it starts. :good2:

I bought an aftermarket one with more robust contacts.
 
#6 ·
Thanks - I'll get a switch this week. Can you recommend a source for a good quality aftermarket switch? eBay is always a good source, but I don't know how I would determine if it is better than the oem.
 
#5 ·
I had the same issue with my Z950R last summer. It would do it every now and then, not all the time. I am still under warranty so I just took it in. I think they had it for a little over two weeks before I got it back. They ended up replacing the PTO switch and the PTO Clutch. If on your dime, I would start with the PTO switch which is what they did at first. Worst case it doesn't fix the issue and you now have a spare for when it is the problem.

I think it took a while to get back because it was an intermittent issue.
 
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#7 ·
Of course other safeties could be the parking brake sensor or I think the control arms need to be in the park position when starting. I always have mine out in the park position anyhow. I wan to say that the seat switch doesn't impact starting. So probably not that. It will just kill things if the parking brake is released. I was going to say look for an error code but I think from helping someone else with a 915B that this model doesn't have the diagnostic codes in the hour meter. On mine it flashes a orange light with a code that you count the flashes and decrypt it into a fault using a chart mounted along side the seat and the right fender.

The odd thing about the PTO switch and starting is I can start my ZTrak with the PTO switch in the run position. In fact 98% of the time I end up doing this because the R models have a PTO kill button on the right control stick which is how I normally turn it off when done mowing since it is easier to reach. The kill button is wired into the safety interlock circuit so pressing it in trips the relay and shuts down the PTO. I have to manually switch the PTO switch off and back on to kick it in again. If I start it with the PTO switch in the on position, the diag light with flash the code for the PTO switch being on when started. It clears as soon as I turn off the PTO Switch.

I think in my case they replaced the PTO switch with a revised one which is supposed to fail less often. When they were testing they also tested the PTO circuit and saw something out of spec with the PTO clutch which is why they replaced that. I would imagine if it is pulling too much of a load it will damage the PTO switch. I haven't bought the service manual yet because I have another year of warranty left. I will get it eventually but until then I don't have the test procedure.
 
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#8 ·
...I think in my case they replaced the PTO switch with a revised one which is supposed to fail less often....
THanks, yes - there is a new part number. I'll probably just pick up the more recent ones from the local dealer and give it a go. There are lots of non-JD switches available, but I have no idea which ones are better and which ones are inferior to the JD switch.
 
#12 ·
I bought mine off of Amazon for $10.
 
#13 ·
The key or the PTO switch?

I thought I bought my booted key off Amazon as well. I went to post a link to one for someone else but couldn't find them. I did find them on eBay and some of the online JD Parts places so maybe I got it from one of those places. It was a long time ago.
 
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#14 ·
#16 ·
Doesn't anybody perform diagnostics?

Let me tell you about something from like 1986 or so that is only tangentially related but I'll not let that get in the way of a decent story.

My wife was driving a 1979 or 1980 Jeep Grand Wagoneer, from when Jeep was owned by AMC. The spawn of Satan.

It got into the habit of just dying on the side of the road. Wait 15 minutes or so and it would start and drive until it happened again.

First trip was to the local garage. They said it was the ignition "computer" and it cost around $200 to replace that. A week later my wife was driving to work and it died in front of an auto repair shop. They said it was the plug wires and charged her $100 for those. Of course it happened again, this time the mechanic thought rebuilding the carburetor would do the trick. I don't remember what that cost but it was at least $100. Third time was not the charm.

At this point my wife said she was going to be driving my company car (a stylish Reliant or Celebrity - can't remember what I had at the time) and I was driving the Jeep until it got fixed. The next day it died on my way home from work.

I had a Chilton's manual that covered the thing and figured it must be electrical in nature. Started following the ignition troubleshooting section. Somewhere around 10 minutes into the job on step 5 or whatever it said to remove the coil from the distributor (it had pointless "points") and measure its resistance while applying heat. 30 seconds later the coil went to infinite resistance.

New coil - $6.95.

For the life of me I cannot remember when we got rid of that Jeep or what we replaced it with. But it never died on the side of the road again. And I've been reluctant to ever let a mechanic do diagnosis on a car I own since then.

Al
 
#17 ·
Al, the PTO switch is a common problem on these machines. It’s listed on the common parts used for service like filters, fluids, belts, and blades. It’s a high use device that’s known to fail. Several members including myself have had it fail. It’s simple and cheap to replace. Problem solved. Always go the cheap and easy fixes first. Known issues are always the absolute next thing to check. After that it becomes get the service manual out and start troubleshooting. :good2:
 
#21 ·
Oh Yes!.. John Deere engineers love the "plunger" type of mechanisms on all their products. I'm thinking each one (engineer) must have starting working in the rest room using a toilet plunder before moving up to the drawing boards. My 2012 Z710A had that trouble at about 29 hours on the meter...failed PTO switch. I ended up buying two and taking apart the factory one. For some reason the manufacturer (China) love the grease or what ever you want to call it they put in it to keep out the moisture dries and the contacts fails. I would say to all John Deere Ztrak owners... buy two and you will be happy that you did when it comes time to replace the failed one.
 
#22 ·
It doesn't look like this is an easy part to change. Any tips or tricks?
 
#25 ·
Using something slim like a credit card will allow you to unlock and pull the existing switch out and replace it easy peasy. All you do is slip it under each long end to push in the locking tabs. On my last one two of the four broke, but who cares? It was destined to go to the trash can anyway.
 
#26 ·
Using something slim like a credit card will allow you to unlock and pull the existing switch out and replace it easy peasy. All you do is slip it under each long end to push in the locking tabs. On my last one two of the four broke, but who cares? It was destined to go to the trash can anyway.
Good point.
With mine I was stuck with not having a new one so I took the switch apart and cleaned it.
 
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#29 ·
PTO Switch Installed

I installed the new PTO switch last night. I didn't have anything thin enough to slip between the console and the switch plate, so I had to remove the console (torx wrenches). The new switch felt more substantial and had a more definite feel to it as I moved it through the different positions. I cycled through a half dozen startup /shutdown cycles with no problem.

But - I don't want to jinx things by declaring success prematurely... I'm going to give it a few weeks before I pop any celebratory corks.

Thanks to all that provided input on this - it helped a LOT!
 
#30 ·
I installed the new PTO switch last night. I didn't have anything thin enough to slip between the console and the switch plate, so I had to remove the console (torx wrenches). The new switch felt more substantial and had a more definite feel to it as I moved it through the different positions. I cycled through a half dozen startup /shutdown cycles with no problem.

But - I don't want to jinx things by declaring success prematurely... I'm going to give it a few weeks before I pop any celebratory corks.

Thanks to all that provided input on this - it helped a LOT!
You could tear apart the old one and look at how bad the contacts look. Maybe clean it up and keep it as a spare.
 
#31 ·
OK, guys, I'm officially declaring success. Ever since I installed the new PTO switch, the 915B has started right up every time that I asked it to. Thanks to all that provided input on this thread!
 
#32 · (Edited)
Update - I was up in the shop this week and tried to start the B. no go. After a few tries, it reluctantly turned over and started, but it won't turn over on the first try.

I'm pretty sure that the battery is good. It's only 2 years old and I keep a battery tender on it. (The battery tender light stays green.)

It could be a different, problem but it looks like the PTO switch has failed again. If that's the case, then I only got 6 months out of the PTO switch that I replaced last summer.

Does anybody know if the switch with the new part number still has the issue with early failure?
 
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#33 ·
Last year...many moons ago I posted here that it would be best to buy two of the PTO switches. Since I have taken my words in hand and now have three on hand. The reason I made that decision, is when I made a trip to my local John Deere dealer, and was talking to the Parts department about the PT0 switch problem, he mentioned that the manufacturer (Delta Corp) made over 50,000 of these #TCA21027 switches, and about 72% are bad, but, they didn't recall them for reason that the owners may not have any problems. I would guess that 72% of those Ztrak owners did such. BTW. these switches are made in USA. Maybe JD should look for a Rice Patty fields mfg. in the Far East.
 
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