Gravely Powermaster 300 No Start/No run


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Old 06-01-18, 10:30 AM
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Gravely Powermaster 300 No Start/No run

Gravely lawnmower won't start or run. Kohler 20hp Magnum V twin engine. I believe that I have it narrowed down to the seat safety switch circuit. I get no continuity reading when I ohm the wires to it. I have the schematics for it and they show a lt grn wire going to a relay and one pink wire leading to a time delay module of some sort.

Thanks for any help,
Mark
 
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Old 06-01-18, 12:59 PM
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For diagnosis (only) you can disconnect the kill wires from the coils and see if it starts and runs. If it does the problem is likely in the safety switches or wiring.

With the kill wires disconnected you'll have to choke it to kill the engine.
 
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Old 06-01-18, 01:21 PM
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Will give that a shot, thanks. I can install a new kill switch if I have to.
 
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Old 06-02-18, 01:15 PM
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Disconnecting the kill wire from the coil allows it to run but I still have to jump the starter from the battery. With the seat sensor out of the picture what would prevent the mower from starting AND running? The other sensors could prevent starting but should let it run. I see from the schematics that there is a relay in the picture other than the starter relay. I adjusted the low speed so I can stall the engine out by lowering the throttle all the way. I guess if I have to I could just go to the starter relay and cut all of the other junk out of the picture.
 
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Old 06-02-18, 01:27 PM
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When everything was working, did the starter turn over with you out of the seat?

If that's a plunger type switch, run it in and out four five times, then fully depress it. See if it all works, then.
 
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Old 06-02-18, 01:52 PM
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Yes, it would start with me out of the seat if the brakes were set and the PTO was off. The switch is a turn only with off/run/start positions. I removed the switch and ohmed the pins and they all do what they should. And if I got out of the seat with it running it would not stall if the brakes were not set and the PTO was on. The schematic shows a relay other than the starter solenoid/relay. Could that relay control both start and run functions?
 
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Old 06-02-18, 02:52 PM
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Can you post a pic of the Schematic ? You do have 12 VDC to the B terminal on the ignition switch right?
Geo
 
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Old 06-02-18, 03:58 PM
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I'm talking about the seat switch as being a plunger type switch.
 
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Old 06-02-18, 04:19 PM
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I didn't probe the 'B' on the switch, I figured it stood for battery and the hour meter, oil low light and PTO are all keyed and working, the switch ohmed good. I don't have third party picture hosting so I don't know how to post up the schematic, can it be done directly?
 
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Old 06-03-18, 04:27 AM
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Oh, the seat switch is bypassed.
 
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Old 06-03-18, 10:12 AM
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Then, the seat switch isn't in the equation since it is bypassed and everything was working without it. The PTO and Brakes aren't in a kill function, but apparently are in the start function as in the starter circuit.

Was this setup working fine before and suddenly stopped, in which case it runs, but you just can't get it to turn over to start it? Once started you're in business. Does that sound close?
 
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Old 06-03-18, 10:35 AM
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Yep, you are right on target. I am thinking that either that seat circuit got it's lines severed somewhere or the relay for the kill line has gone out. Oddly enough and fortunately, it died just as I was parking it last week so it wasn't out in the yard. I thought I had bumped the key when I dropped the deck when I stopped but apparently something crapped out on me at exactly that time.
 
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Old 06-03-18, 11:41 AM
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Is there a serial # on that mower?
Geo
 
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Old 06-03-18, 12:26 PM
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I have the numbers off of the deck but not the tractor, where would it be located
 
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Old 06-03-18, 01:08 PM
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Donít know where the numbers are but I think I found out what the TD Relay does,

I will assume that you looked at the link I posted in message #7. That wiring diagram is for the GT20. The time delay relay ( #17 ) is for keeping the engine running for times when you bounce off the seat. Depending on the module, it can be up to 30 seconds. If you have the brake on, the PTO clutches off, and the tractor in neutral, the relay should be out of the circuit and the engine will keep running without anyone on the seat.
Geo
 
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Old 06-03-18, 03:13 PM
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There is no safety circuit that latches a relay that will last 30 seconds! The reason for safety circuits is to keep stupid people from killing themselves and their kids!

Inaccurate information is twice as deadly as NO info!
 
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Old 06-03-18, 04:08 PM
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I don't see a link in post #7 here. So far I have been unable to find the time delay module that shows on my schematic, I haven't found that fuse that's supposed to be there either.
 
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Old 06-03-18, 06:16 PM
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What are the letters on the I switch ? Does this schematic look like the one you are using?
https://www.partstree.com/parts/grav...ohler-engines/
Geo
 
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Old 06-04-18, 04:35 AM
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That is the schematic and the I switch is marked as that one is. I have not been able to locate the fuse or that time delay module.
 
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Old 06-04-18, 04:45 AM
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Does the starter solenoid click when you turn the ignition switch to start?
This link may help identify relays. http://www.partstree.com/parts/grave...trical-system/
Geo
 

Last edited by Geochurchi; 06-04-18 at 05:57 AM.
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Old 06-04-18, 09:20 AM
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OK, that time delay is going to be the seat switch, which is bypassed. No, no starter solenoid click when turned to start. The oil pressure light does light and the PTO switch functions when the key is on.
 
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Old 06-04-18, 10:45 AM
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Where on that I switch to you have voltage to ground using test light or meter?
Geo
 
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Old 06-04-18, 12:24 PM
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On which key position(s)? I won't be able to check that until Tuesday afternoon.
 
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Old 06-04-18, 03:04 PM
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What terminals have power in all 3 positions Start Run Off
Geo
 
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Old 06-04-18, 03:23 PM
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The PTO and Brake switch are in the starting safety circuit. The PTO is also in the kill circuit. Not all PTO switches function the same, it depends on the manufacturer and how they wire the safety circuit/how many safeties are in the circuit.
If the brake switch checks good, I would try a new PTO switch.

While the seat switch is not in the starting safety circuit, you may or may not be able to simply "Jump" it. Some have separate plunger in the connector that must be made (which happens when the connectors are plugged in) that must be made for the seat switch to work. If the brake and PTO work and it starts, symptom of the seat switch would be the engine shutting down when you released the Brake.
 
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Old 06-05-18, 05:08 AM
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The seat sensor has been bypassed for about 20 years so I do not suspect the bypass itself. I thought that the seat sensor was in both the start and run circuits but since I jumped it so long ago I don't recall. I'll check out that ignition switch today but I did ohm it and it seemed to pass on all pegs. What items are involved in both the start and run circuits besides, possibly, the seat sensor?
 
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Old 06-05-18, 05:34 AM
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the pto and brake switch are in the starting safety circuit. The pto is also in the kill circuit
. .
 
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Old 06-05-18, 09:16 AM
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Itís good the I switch rang out OK, but if no power is getting there it doesnít mean much, looks like neutral safety switch and brake switch may be involved also
Geo
 
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Old 06-05-18, 10:56 AM
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OK, with the switch in 'Off' position I get power at 'B' and intermittent bleedover of .01V on 'I'.
Key 'On' gives power to everything but the 'S' and 'Start' give power to everything but 'A' and the low oil pressure light goes off.

Thanks, I didn't catch that the PTO is involved in both circuits. For some reason I thought that the brake would be in the kill circuit too but with the seat bypassed I wouldn't notice that either way.
 
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Old 06-05-18, 11:24 AM
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The PTO switch has five lugs on the back two to the left on one connector block and three to the right connector block. In the off position the two lugs on the left are closed and in the on position the center lug to bottom on the right are closed, the top lug does not have a wire in that connector block.

Additionally, I get no continuity anywhere on the brake safety switch, not to ground from any of the lugs and nothing between the lugs.

Edit: After revisiting this I find that the bottom lugs get continuity when the brake is set and the top ones get it when released. Where would I find the neutral safety switches?
 

Last edited by Walleye Hunter; 06-05-18 at 02:22 PM.
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Old 06-05-18, 02:33 PM
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When the I switch is in the start position do you have power at the black wire to ground on the solenoid ? also the Brown wire to ground, I have never seen to control wires on a starter solenoid.
Geo
 
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Old 06-05-18, 03:17 PM
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Where would I find the neutral safety switches?
It depends on what tranny you have and how it shifts...when the drive lever/pedal or whatever is in neutral, it should detent on a switch. Maybe under the fender..?

The brake switch is working then, in a sense it is IN the kill circuit but only activated by the seat switch. IE: if the seat switch opens with the engine running and the brake not set, it will kill the engine only because the seat switch activated it. That is the reason for the double pole.
 
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Old 06-05-18, 05:48 PM
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Yes, both of those lugs have (had) power when the switch was turned to start. Then I bumped the other end to ground and blew the relay out. I'll have to get another relay before I can do anything else.
 
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Old 06-05-18, 10:18 PM
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:facepalm:
Good Luck guys!
 
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Old 06-06-18, 04:26 AM
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What relay did you burn out? and that motor never turned over, if you jump the 2 big terminals on that starter solenoid it should turn over then.
What color wires are on that PTO switch?
Geo
 
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Old 06-06-18, 08:36 AM
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I burnt out the black, cube shaped one with the diode in it. The PTO wires are orange, blue and looks like purple.
 
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Old 06-08-18, 11:30 AM
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OK, I'm back in business, it was a fuse that blew, not a relay and that fuse was tough for me to find. I don't know why I posted that the unit is a Powermaster, it's not, it's a Promaster 300. My no start remains the same and the number of possible causes is dwindling. I also have noticed another problem that may or may not be associated with the no start. It's hydrostatic drive and it used to have backpressure on the pedal when running. That back pressure is not there right now and when traveling downhill it has no speed control without activating reverse. The schematic shows two neutral sensors but I have yet to find where they are located. The only thing that I haven't trouble shot in the steering tower is the delay timer and I don't know what to do with it, it has about four wires running through it.
 
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Old 06-08-18, 04:04 PM
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Do you have the S/N ? This site maybe some help.

https://support.gravely.com/manuals/
Geo
 
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Old 06-08-18, 05:01 PM
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This is getting good

 
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Old 06-09-18, 03:28 AM
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Ehhhh, why is it getting good?

I have all of the manuals and they show parts but they don't show where the parts are planted on the machine. The electrical schematic shows two neutral sensors and the direction control schematic shows a neutral lever, I'm going to guess that the neutral switch(es) should be around that lever/control assembly somewhere. I'll have to find a way to get under this thing so I can see that stuff. Any thoughts on why the forward direction has gone soft on me? IIRC the serial number is under the seat and I'll see if I can find it, I thought I had it written in my books but no luck there.
 

Last edited by Walleye Hunter; 06-09-18 at 04:14 AM.
 

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