ZD326S - Making me lose my hair...electrical issue

[lcollins42]

I purchased this zero-turn mower in 2007. It has been a great mower, but it has been plagued with a recurring electrical issue the past couple of years.

When the engine is cold (not as in frozen, just as in hasn't been run in a week), it acts like the battery is dead. It is sluggish to turn over and eventually the juice is drained from the battery. Put it on a jump charger, and it cranks up just fine. I took the battery in and had it checked, and it checks out OK. Battery terminals are clean.

When the engine is hot (not overheated, just having been running for an hour or two), if I kill the engine to eat lunch, it won't restart until the engine has cooled all the way to "cold". And at that point, you'd never know I had problems starting it at the beginning of the day. It cranks right up and runs just fine. And I just have to be conscious that I can't kill the engine until I'm finished mowing unless I want to wait two hours to start it again.

I have replaced the battery, the starter, the alternator, and all of the position sensors (seat, brake pedal, etc). The Kubota dealership in Angleton (Bobby Ford) replaced the wiring harness.

And the issue persists. Right now, I'm waiting for it to cool down again, and I'd really rather be mowing.

 

[Robert Galka]

Change the battery.

 

[lcollins42]

Change the battery.

The battery is less than 3 years old, and has been checked. Why do you recommend changing the battery?

 

[whitetiger]

Check to see that your unit had this PSB performed.

 

[lcollins42]

Check to see that your unit had this PSB performed.

GREAT CALL! Look at the condition of that wire. I guess I know what I'm spending my afternoon fixing. Hopefully that resolves this issue once and for all!

 

[lcollins42]

Check to see that your unit had this PSB performed.

And...THANK YOU!

 

[skeets]

Well that bulletin explained it better than, me saying check your ground

 

[lcollins42]

Check to see that your unit had this PSB performed.

UPDATE: I pulled the battery so that I could better get to the wiring harness. After I laid open the wiring harness, that ground wire insulation is melted from the post all the way to the fuse box. In my experience, wire insulation doesn't melt unless it is exposed to too many amps, but that is primarily with control panel circuitry (AC vs DC voltage).

I'm a little hesitant to continue following this wire up into the fuse box, primarily because I'm not sure what to do then. There isn't enough wire left for me to have any idea what gauge it should be for replacement, and honestly, I've never needed to take a fuse box apart. LOL

Is it time to call a professional? And should this wire have been replaced when the dealership replaced the wiring harness? Sure seems like it should have...

 

[whitetiger]

Yes, that wire is part of the wiring harness.

 

[Mark_BX25D]

Is it time to call a professional?

That's your call. Depends on your comfort level. I'd replace it, myself. Count it an adventure!

I'd guess that to be about 10 gauge.

But even if it should have been replaced as part of the wring harness, don't expect to get it re-done for free. Some not-right thing made that happen, and that some not-right thing needs to be found and fixed, or it will just get fried again.

I noticed in all of this that nobody mentioned replacing the battery cables. If that fried wire is a ground wire (I'm guessing it is), it's likely your battery ground cable is not happy. Or where it connects to the frame. Or both.

I'd replace both battery cables and clean up the connections (both ends of both cables).

That's in addition to replacing the fried wire, of course.


I like to upgrade battery cables one gauge size. (anything more is a waste) I get them made here. Good service, good quality, good prices. I also use military style battery terminals.

Makes a trouble free setup.

 

[whitetiger]

I'm a little hesitant to continue following this wire up into the fuse box, primarily because I'm not sure what to do then. There isn't enough wire left for me to have any idea what gauge it should be for replacement, and honestly, I've never needed to take a fuse box apart.

There is no ground wire at the fuse box, but it does go to the relays, controller, regulator, gauges, and warning lights, etc.

If I remember correctly, it is a 14-gauge wire.

 

[Mark_BX25D]

There is no ground wire at the fuse box, but it does go to the relays, controller, regulator, gauges, and warning lights, etc.

Sounds about right. If the main battery ground cable is making a poor connection (cable or connnections), then, when you try to start the beast, the current will seek a path back to the battery, and any other ground wire (like our fried friend here) will be an available path, but the current will be too much for it. Smoke follows.

Check that main ground cable. I'm betting you'll find a problem there.


Remember, a cable can look fine on the outside, but be corroded inside the jacket.

 

[GreensvilleJay]

That little ,fried wire got damaged as a LOT of amps went through it because some OTHER wire wasn't doing it's job. I've seen similar damage on other machines,
As Mark says, check the main ground cable and it's connection to the tractor. Heck just replace with a new one

 

[whitetiger]

the current will seek a path back to the battery

The burned wire does not go to the battery. The wire was damaged from either a failed component or the harness has been damaged shorting a positive wire to the ground wire.

 

[ctfjr]

Sounds about right. If the main battery ground cable is making a poor connection (cable or connnections), then, when you try to start the beast, the current will seek a path back to the battery, and any other ground wire (like our fried friend here) will be an available path, but the current will be too much for it. Smoke follows.

Check that main ground cable. I'm betting you'll find a problem there.


Remember, a cable can look fine on the outside, but be corroded inside the jacket.

I'm not following this 100%. It seems to me that the ONLY path back to battery is through the ground cable from the battery to chassis.

My guess is I would go with your suggestion to thoroughly check the battery connections, ground connection and cables. If there is a higher resistance than normal at a connector then a large current draw (like starting) will result in a lower voltage being delivered to the starter. It will crank longer and draw a lot more amp/seconds than it should.
I had a Kawasaki MC once that had a 'hot start' problem. It just wouldn't and if i kept trying it would kill the battery. I had to wait 30 minutes to restart (or park on a hill).

 

[cthomas]

And just so you know(if you don't) you can always add ground wires. Had a Chevy Chevette once that would crank, but, no start. Tested the car and found the distributor was not getting a ground(distributor bolted to engine block), it got a new coil and distributor before I inherited it from another tech. For years the other tech was convinced I did not fix that car. Added a wire from radiator support to condenser bolt(remove wire it would go back to a no start condition)((Owner of the shop wanted to prove to the other tech)). When the other tech bought the shop first thing he did was fire me! I did get last laugh as within 9 months the bank foreclosed on the shop.

 

[whitetiger]

And should this wire have been replaced when the dealership replaced the wiring harness?

You probably should contact your dealer as they replaced the wiring harness, and yet they did not perform the PSB which addresses the exact condition you were experiencing. Their failure to perform the PSB has damaged your harness and as you open the loom, will probably find more damage.

Your picture in post #5 clearly shows the harness ground wire is installed with the negative cable rather than on the separate bolt per PSB-2008-028-B.

The PSB is attached to post #4 and the wiring diagram is attached to post #11.

 

[GreensvilleJay]

According to the wiring PDF what WT supplied , everything except the starter and 3 sensors is 'grounded' through 3 black wires with rings on them. Lower right of the diagram. 2, #12 wires with M8 rings, 1, #14 with a M6 ring. All the current flows through them to the chassis, then to ground battery cable and finally into the battery.
100% of that wiring harness needs to be opened up and inspected and since it was dealer replaced, it should go back and have it done, right and free.

 

[Mark_BX25D]

I'm not following this 100%. It seems to me that the ONLY path back to battery is through the ground cable from the battery to chassis.

Depends on the vehicle. Many have a separate ground from the battery to the frame or body, and that ground is in addition to the main ground which either goes to the frame, or sometimes, right to the engine block.

If that is the case, and the main connection is impaired, starting current will flow through the smaller, separate ground, and fried wires are the result.

I don't know if that applies to this vehicle, but it sure sounds like it.

100% of that wiring harness needs to be opened up and inspected and since it was dealer replaced, it should go back and have it done, right and free.

Agreed! Emphatically! If one wire in a bundle is melted that badly, it's not the ONLY one that is damaged.

 

[whitetiger]

Depends on the vehicle. Many have a separate ground from the battery to the frame or body, and that ground is in addition to the main ground which either goes to the frame, or sometimes, right to the engine block.

The ZD326 like all ZD series mowers has only the main ground cable running from the battery to the frame and all other ground wires are attached to the frame.