Ryobi ZT480EX won't move - electric zero turn (8 beeps)

[MasterOfNone]

My ZT480EX (AKA - RY48ZTR100) is giving me a hall sensor error (8 beeps) when I press left lever. I found some troubleshooting steps in a PDF guide on this forum.

One recommendation was to swap the left and right hall sensor plugs. When I swap the left and right hall sensor plug (located under the seat in front) the 8 beeps stay on the left lever. As I understand it, if the problem was truly the hall sensor the beeps should have swapped to the opposite lever when the plugs were swapped.

My question is: what do I test next?

I'm using the attached troubleshooting guide, and I have tested the drive motor controllers as well. Most all of the tests I did passed, but I had two test that don't look quite right, however they're identical on both left and right drive controller so I'm thinking they might be okay since my error beep is only on the left side.

Two drive controller test that look funny:

1) Test Power and Ground to Output Circuitry (Diode Mode): With battery unplugged, I tested the heavy ground wire (black) to each phase terminal was normal (OL) but heavy positive wire (red) to each phase terminal was OL, which my research says is not normal (normal = 0.45v). Again I didn't worry about this since both left and right controller tested the same and only one side is giving me problems.

2) With battery unplugged I tested the heavy ground and positive wires to each other tested as .4M ohms on both left and right controller power wires. I tested again one week later and it changed to .6M ohms. (Normal = 3M ohms or OL).

Any help would be greatly appreciated! I'm familiar with electrical safety and can use a multimeter, but the complexity of this mower is somewhat overwhelming.

 

[Auto Doc's]

Hello M,

Welcome to the forum.

48V is intimidating to many folks unless they deal with golf carts often enough to understand them.

These electric riders are still a very new experience for many of us. I work on a lot of different equipment, and the same principles of electrical diagnostics apply.

The attached manual on your posting has a flow chart and wiring diagram and that is more than most folks have. You have already tried swapping sensors L/R and the problem is still on the left side. That tells me there is a wiring issue.

To conduct a load test on the wires using simple leads and a halogen headlamp bulb. Disconnect the batteries in the machine and use a conventional 12V rider mower battery. Make yourself a simple loop circuit, then test 1 wire at a time using that loop.

Ohm testing only confirm a connection is present but does not confirm if it can carry a load. One or two single strands can pass an Ohm test but not carry amp load.

 

[MasterOfNone]

Thanks for this!
With the halogen headlamp, what am I looking for as a positive or negative result?
Bulb lights up? Or something else?