I have a Honda ht3810 riding mower that will not crank. Battery is fully charged, headlights come on, but won't crank. I can start it by jumping the starter solenoid, but that's it. I have checked all safety features such as seat switch, blade engagement, pto engagement, all seems o.k.

Well, it could very well be the solenoid then, if it operates when you "jump" the solenoid.

Mowerman is correct, sounds like you need a new solenoid but remove, clean and reinstall the wires to the solenoid first and retry. If it still won't crank get a new solenoid.

Reply to answers. Already tried new solenoid(external) did not work either.

Don, you are saying you can jump past the solenoid and it starts but a new solenoid did not fix the problem, right? Are you jumping at the solenoid terminals or from further upstream in the electric system? Terminals are clean, correct?

Now it makes me wonder ball, what I am suspecting is the usually red wire that runs up to the key switch may not be making contact, or the fuse could be blown between the switch and the solenoid.

I am perplexed. I jump the starter solenoid with a screwdriver from 12 volt power(which is at the starter) across to the 2 terminals of the solenoid and it will start. I have no power with a test light with key off or on, but do have juice in the start key position. I used a auto solenoid (off a Ford truck, new and used) and still won't work. I am really puzzled. I checked fuses, switched some common relays around with no luck. As much of a cheapskate I am I may take it to Honda to get looked at, but the keyword is CHEAPSKATE! Let me know what you think.

You should have power to one of the main post of the solenoid at all times, this cable comes straight from the battery. Then as the key is turned to start, you should have power to the other main post of the solenoid and then to the starter.

Don, the solenoid is a like an electrically operated switch. It gets power from the battery but doesn't transfer that power to the starter until you trun the ignition switch. Tell us again, do you get 12vdc at the red terminal of the solenoid? If you do the solenoid is bad but we should also check the ignition switch. The small wire from the ignition switch to the solenoid should show power when the key is turn, does it?

Sorry I didn't get in more quick. The solenoid has 3 terminals, I have battery voltage at 1 terminal with key on, I have just under battery voltage (11) at 2nd terminal with key in start position(from ignition switch) , I never have power at 3rd terminal to starter at any time. I can jump across terminals 1 & 3 and it will turn over. Like I said I have tried an external solenoid ( $10 versus $80 Honda ) didn't work and I have to beleuve the starters O.K. Let me know what think. Thanks everyone, Don

OK, when you hooked up an external solenoid, to test with, did you ground it well to the units frame? And if you are not getting voltage to terminal 3 as you called it, which should be a large wire that runs to the starter. Your solenoid is bad. You should be able to get an aftermarket solenoid with the correct number of posts and do so for less than $15.00.