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My Father has had a brand new Toro Titan HD 1500 (model number 74451) 52" commercial zero turn in his possession since 2018. He only uses it in a residential capacity mowing probably less than 1 acres of grass. Last October in 2021 I replaced the starter solenoid with another brand new Toro unit (Toro part number 117-1197.) Today he tells me the mower won't start again, only getting clicks. I tell him to give the solenoid a few light taps, and that worked. What in the heck is going on with these starter solenoids and is this a common problem for Toro OEM parts? If so, what is an aftermarket part you'd recommend that isn't as failure-prone as the Toro solenoid in question? Thanks. PS - this Toro has only about ~60 run hours on it presently. Super low as it's a commercial mower used in residential capacity.

I agree with Rivets, try moving ground wire by hand.

I’m betting that the ground wire going from the solenoid to the chassis is loose or dirty. Trace this wire and clean and tighten the connection make sure you have a good ground.

Rivets said:

I’m betting that the ground wire going from the solenoid to the chassis is loose or dirty. Trace this wire and clean and tighten the connection make sure you have a good ground.

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Next time I'm there I will take a look at the ground wire although I don't recall anything being loose last year. Also the mower has been used quite a few times this year and perhaps there have actually been two solenoid failures this year if I recall him mentioning, I believe earlier in the year he had an issue where he is getting clicks only.

I should also mention that I replaced at the beginning of last year in March 2021 as it seemed to have died a premature death. I remember posting about that here as well and it was mentioned by some members here that the original battery was underpowered with too low of cranking amps. I "upgraded" to maybe what should have been in the mower. Although that brings back more memories. My Father mentioned when the Toro dealership delivered this mower in 2018 that upon arrival the battery was "dead" and they had to go back to the shop to swap it out. There's a possibility that the delivery guy re-installed the wrong battery (ala too low cranking amps) and/or maybe the battery wasn't dead at all and it was a solenoid issue from day 1??!??!? Who knows, that's going on 4 years.

To me unless you are living in the north where temperatures can get cold, a battery with low CCA shouldn’t be a problem. You might have a charging system that is not working properly, shorting the life of the battery. This will reduce the voltage available at starting, which will show up as the solenoid only clicking. Next time you start the unit attach a volt meter to the battery and read starting voltage. It should not drop below 10 VDC. If it does your battery is not holding a charge. After you get it started, read charging voltage. It should read between 13.2-13.6 VDC. If it does not your charging system may be bad. Do both of these tests after you have cleaned both of the ground connections I previously mentioned.

Toro safety switches are usually the main culprits in this situation. The parking brake switch, seat switch, and steering switches.

MParr said:

Toro safety switches are usually the main culprits in this situation. The parking brake switch, seat switch, and steering switches.

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I understand, when a safety switch is engaged it does not send power to the solenoid, no click or clunk at all.

Blaine you are correct, that’s why I suggest voltage tests and bad connections.

Rivets said:

Blaine you are correct, that’s why I suggest voltage tests and bad connections.

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Plenty of "whoopsies" on this Zero Turn as the transmission levers must be disengaged, parking brake on, and butt on seat in order to start. Or if you engage the parking brake with transmission levers engaged it will also kill the motor. But then again no clunk heard from solenoid under these "safe" conditions.

Moreso the old solenoid livened up when I gave it some taps myself. And as he had to give the new solenoid a few taps the other day to liven it up. I suppose the taps could be seating a poor connection but there is absolute zero rust or corrosion on this lawn mower anywhere. Stored indoors and only washed twice! Unless I find something very unusual at this grounding location (I doubt I will) I guarantee you that the electrical connections at the solenoid itself are tight and pristine. I evaluated them just last October 2021 when the solenoid was replaced.

Here's a thought;



I believe this solenoid may be grounded via the mounting bolts. The smaller wire on the lower studs is from the ignition switch only. I believe there were only 3 wires from memory, the 2 large gauge between starter and battery and then the low amperage connection between solenoid coil and ignition. There was no corrosion between coil and body of zero turn.

To the best of my knowledge on any 4 post solenoid, one of the small terminals must be grounded and they do not ground through the mounting bolts. Second, you state that there is no dirt or corrosion on the frame or coil. Where grounds are connected I’ve always removed the paint also, which Gives me the best ground connection possible.

Rivets said:

To the best of my knowledge on any 4 post solenoid, one of the small terminals must be grounded and they do not ground through the mounting bolts. Second, you state that there is no dirt or corrosion on the frame or coil. Where grounds are connected I’ve always removed the paint also, which Gives me the best ground connection possible.

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The way it's fastened is as it was from the factory, minus the removal of the original solenoid and installation of the new. When I'm back at his place I'll take a look at if I can find any grounds. But if the solenoid is giving a good "clunk" I don't suspect a ground to be at fault, especially since tapping the solenoid temporarily cures the problem.

I stopped by to check it out. It appears that the starter is the actual failure. I even made a short video you can see here. I gave the starter a couple of very light taps and it fired right up. Seems that the solenoid is not at fault, and maybe it wasn't last year either - although tapping the solenoid seemed to do the trick last year as well, who knows, they're in relatively close proximity to one another either way.

Watch video here:
https://vimeo.com/717703811

This particular Toro Titan has the Toro V-twin rather than the Kawasaki or Kohler motors. Does anyone know what the correct starter is? Ereplacement parts gives a part number of 136-7880 while the Toro website gives a part number of 133-9828. As far as I see visually online they are identical starters, just different prices.

Toro updates their part numbers regularly. The 136-7880 will work.
So will a starter for a Loncin 708cc engine aka Predator 708cc engine.

MParr said:

Toro updates their part numbers regularly. The 136-7880 will work.
So will a starter for a Loncin 708cc engine aka Predator 708cc engine.

Loncin 708CC Heavy Duty Starter

708cc starter vpe part # 032320190001-lon

www.vpowerequipment.com

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Thank you. I have a new, open box Toro #136-7880 starter on order for $175. I really hope this is the end of the line for starter/solenoid failures!



When I get around to it I'll dissect the original starter. Can't imagine why at only 59 hours it would be crapping out other than it's purely a lemon?!?

Before you start throwing more parts at it, have you done any volt Drop tests as I recommended earlier? Troubleshooting procedures would indicate which parts may be bad. Tapping on parts are not the best way to diagnose a problem. They only give you an indication of which circuit is causing the problem, not part. Just because connections look good and came from the factory that way, doesn’t mean they are good. Personally this would be the first time I’ve heard of this problem, but even that doesn’t mean I’m on the right track or giving good advice.

Upon nearly replacing the starter as we have the brand new replacement in hand, we noticed that the main ground between the battery and the engine block was loose. We tightened that up and did not replace the starter.

From what I can see there is no body/frame ground. It appears that the entire mower is grounded through the engine block. Is this true? The only two ground wires coming from the battery are the larger gauge wire which connects to the block and then a smaller wire, which I am not sure of where that terminates.

Would that make sense that the starter would not engage but that the solenoid would produce the loud "thunk" as heard in the video due to a loose ground on the block? I'm assuming that the only way this ground would have loosened up would be from vibration alone, although the mower only has about 60 run hours on it now which is low and as I mentioned before is only used once per week and not in a commercial or business application.

You are correct in your assumptions about the grounds. Grounds come loose for a variety of reasons and that is why every experienced tech will tell you, “ALWAYS CHECK GROUND CABLES AND CONNECTIONS FIRST”

Reporting back to say that the issue with the starter has not returned since the ground connection on the block was tightened. There was likely never an issue with the solenoid that was replaced last year either I'd assume.

Thank you for letting us know, most times we never hear back.