solenoid clicks but no crank

Messages
666
Location
Chicago
so this is for a zero turn riding mower not a car, but bitogers are far more knowledgeable than the tractor forums.

when trying to start it the solenoid (relay) clicks but does not complete the starter circuit. the relay does not close. the coil + terminal does measure 12V when attempting to start. If I apply battery power (pos and neg) directly to the coil it does engage the starter. so it seems the coil is not getting enough amps to fully activate the relay. I measured DC current across the wires connected to the coil (while disconnected from the solenoid) and got varying results about 0.5A ~ 0.9A. I expected this to blow the 5A starter fuse, because it should be a short across the battery when the key is engaged, right? but only got <1A.

I also put in a new solenoid and it does the same thing. and both test out the same. so I put the old one back in.

since I'm getting 12V at the coil it must mean none of the safety switches are open. but I'm also not getting much amperage.... so what does this mean? could one of the safety switches be dirty/corroded causing extra resistance? I was able to meaure all but the seat switch and PTO, and they all measured <1.0ohm when closed.

for now I can start the mower by shorting the solenoid contacts with a big wrench, but I'd rather use the key.
 
Messages
2,872
Location
High Tax Illinois
Look for the safety switches. Under the seat, guards are in place etc. I'll bet one is either bad or got loose, not making contact to close the key on start mode. You can also jump across the safety switches to see if any are bad. Short piece of wire with alligator clips on each end.
 
Messages
2,512
Location
Americus, GA
Some of the lower end residential zero turns have some really cheap safety switches. There are usually four. There is one for the seat. Unplug that one and make a jumper and try starting it. No start? Move on to the other three. There is one for each handle. Manipulate one handle at the time while turning the key. No start? Move on the the parking brake switch. Engage and disengage the brake handle while turning the key. No start? Punt.
 

sky jumper

Thread starter
Messages
666
Location
Chicago
ok but if it were a bad safety switch I'd get no solenoid click at all, right? and no 12V at the coil terminal, right? but I'm getting voltage and clicks, so it can't be an open safety swtich... perhaps a loose connection, i suppose. the only connection I haven't checked is the seat switch because I can't reach it with the seat on. i'll remove the seat and check it.
 
Messages
2,512
Location
Americus, GA
ok but if it were a bad safety switch I'd get no solenoid click at all, right? and no 12V at the coil terminal, right? but I'm getting voltage and clicks, so it can't be an open safety swtich... perhaps a loose connection, i suppose. the only connection I haven't checked is the seat switch because I can't reach it with the seat on. i'll remove the seat and check it.
Not necessarily. My former Toro had a big problem with those cheap plastic switches.The brake switch was the biggest problem. I could hear the starter solenoid clicking. I had already jumped the seat switch and still no start. With the seat switch jumped, I could move on to the others without being in the seat.I manipulated the brake switch while engaging the starter and it fired up. I replaced the switch. However, that only worked for a little while. Every so often, I would have to fiddle with the parking brake to get it to crank. Do you have access to the wiring diagram?
 

sky jumper

Thread starter
Messages
666
Location
Chicago
Not necessarily. My former Toro had a big problem with those cheap plastic switches.The brake switch was the biggest problem. I could hear the starter solenoid clicking. I had already jumped the seat switch and still no start. With the seat switch jumped, I could move on to the others without being in the seat.I manipulated the brake switch while engaging the starter and it fired up. I replaced the switch. However, that only worked for a little while. Every so often, I would have to fiddle with the parking brake to get it to crank. Do you have access to the wiring diagram?
interesting. goofy soft failures are the worst sort. I don't have the wiring diagram kubota charges for it I think.
 
Messages
2,512
Location
Americus, GA
interesting. goofy soft failures are the worst sort. I don't have the wiring diagram kubota charges for it I think.
The brake safety switch on my former Toro had multiple wires going to it. I can’t remember but, I believe that the steering switches and the seat switch were all tied into the brake switch. Your Husqvarna may be a little different.
 
Messages
590
Location
North Florida
If the safety switches are OK then check the PTO switch that engages the blade clutch. If it has a short in it the engine won't be allowed to turn over because it thinks the blades are engaged. You can use a multimeter to check the continuity on it. Check YouTube for instructions. My Skag had the switch go bad and it would not turn over. Replacing the PTO switch fixed it.
 
Messages
30
I have two ideas for you. 1. I know you said you got 12V at the coil. But take your ground wire from the battery, and scrub up both ends. They're cheap for a tractor.

2. The safety switches - if you feel so inclined, and believe all those safety switches are an unnecessary form of government intrusion in your life like I do, cut the **** wires off the switch and splice them all together. If you don't want to cut them, see if you can remove the wires from the switch and jump them with an automotive style blade fuse. Easy fix.
 
Messages
136
Location
belle chasse
even if your solenoid clicks (coil picks up to contacts) the contacts themselves may be so pitted you are not getting contact. My bet is the solenoid is bad even though you hear a "click". I've had this happen and took the old solenoid apart just to see and you can see the carbon deposits on the contacts.
 
Messages
25,966
Location
MA, Mittelfranken.de
Test it just like any other starter, jump the starter itself, turns over the battery, cable and connection are okay, you have an issue getting juice to the trigger terminal or a bad solenoid.
Not turning over battery, connection or cable. Auto Mech 101. I would check the battery first.
 
Messages
2,363
Location
South Carolina
He has tried a new solenoid but has the same problem. Battery bad, poor chassis ground connection, poor battery connections, poor electrical connections, poor starter to chassis ground connection. He's getting voltage to the solenoid but no current = bad connection somewhere in the system.
 
Messages
115
Location
Boston, Massachusetts
I had this exact problem with my 1989 John Deere STX30 lawn tractor. Solution was to add a simple relay to the starter circuit. The relay is activated by the original starter-solenoid trigger wire, then delivers 12 volts from the battery cable at the starter to activate the solenoid, which then activates the starter motor.

Before installing the relay, I tried new starter solenoids, new starter motors, cleaning electrical contacts, sanding electrical grounds, charging the battery, replacing the key switch, etc., etc. Nothing worked to resolve the solenoid-clicks-but-starter-won't-spin problem until I installed the relay. My best guess is that the voltage drop through the maze of safety switches and key switch lowers the voltage to the solenoid enough that it clicks, but doesn't close the electrical contacts within to pass voltage to the starter motor.

BTW, my 1989 John Deere STX30 lawn tractor is still used to mow about an acre of grass every week.
 

sky jumper

Thread starter
Messages
666
Location
Chicago
battery, solenoid, starter are all good.

I think Exit32 and ka9mnx nailed it.... bad connection somewhere impeding current to the solenoid coil. I just don't know where. the mower is very clean, all the electrical connectors and harnesses are clean. battery terminals super clean no corrosion. meanwhile I have a 30yr old simplicity covered in grime & crud & oil and it fires right up every time, even after sitting for years.

I do have a question about the solenoid coil wires --- why are there 2? why not just the +12V wire, with the ground coming from chasis mounting? I can't trace the ground wire through the harness back to anything so I can't inpect those connections. if it were grounded to chasis at the mounting location that would be an easy thing to check/clean.
 

sky jumper

Thread starter
Messages
666
Location
Chicago
I believe I found the wiring diagram, attached. its for a Z122 but i'm pretty sure its the same.

there's a bit more going on here than I thought. there's 2 "starter relays" in the circuit as well. I honestly don't see the point of relay (9). Relay (5), however, is interesting. it completes the ground connetion from the solenoid coil if the motion control levers, PTO, and brake switches are all closed. so there's the answer to my question about the 2-wire coil connection.

so I suppose that starter realy (5) could be the culprit. I guess I can test that out by ohming the coil wire to battery ground.

There's also 2 diodes in the mix, but they are not identified and I have no idea where they are. i'm guessing a bad diode could be a current limiter in the solenoid coil circuit.
 

Attachments

  • Z122R (engusa)-9Y111-12014.pdf
    96.5 KB · Views: 16
Messages
25,966
Location
MA, Mittelfranken.de
He has tried a new solenoid but has the same problem. Battery bad, poor chassis ground connection, poor battery connections, poor electrical connections, poor starter to chassis ground connection. He's getting voltage to the solenoid but no current = bad connection somewhere in the system.
I understand that I meant jump the starter main not through the solenoid. I see you is into the other wiring now so no matter.
 
Messages
115
Location
Boston, Massachusetts
Apparently, this problem is so common that a number of companies make/sell kits to add a relay to existing starter circuits. For example:

 
Messages
2,363
Location
South Carolina
Diodes are used in properly designed solenoid (or relay) circuits to bleed excess current when the the field (solenoid coil) collapses. They are also used in circuits to allow current to flow only in one direction not allowing the current to back feed into a circuit.

There is only one starter solenoid and one solenoid relay. When you activate the start switch arre you sure you are hearing the starter solenoid or are you hearing the solenoid relay? If you are hearing the starter solenoid then the solenoid relay (5) is working properly (along with all the other interlock switches everyone is asking you to check.

If you are hearing the solenoid click then all the circuits are working correctly which points to a wiring or connection problem from the battery through the solenoid and to the starter. Or a bad (new) solenoid.
 
Top