Need help with an old garden tractor...

[rusty ol ranger]

I got a 78 yardman GT i finally sourced an original style engine for and am now trying to figure out a wiring issue.

The key wont start it.

It has a ford style starter solenoid but with only one little post.

I found a wiring diagram online looks like power goes from key, to a PTO safety switch, then up to the solenoid to tell it to get to work.

Im not getting any power at the solenoid wire. I jumped past the safety switch as i had 12v to it, still nothing.

So i ran a wire right from the safety switch wire (only hot during cranking), to the solenoid wire. Had 12v at solenoid wire...plugged in solenoid,..nothing.

Checked wire...0v.

Unplug wire from solenoid...12v

Plug into solenoid...0v

WTF is causing that? Bad solenoid? Ground?

 

[franklin2]

Bad connection somewhere. Electricity is just like a garden hose with a kink in it. The kink is the poor connection. Just like the garden hose has plenty of pressure with the kink, until you open the nozzle and it fizzles out, your start wire is the same. Don't use it (meter uses just about nothing) and you have 12v. Go to use it (hook the solenoid up) and the voltage drops to zero, just like the garden hose fizzles out with the kink in it.

The trick is to leave the load on the wire, and THEN start checking places with the meter. In this instance it may take two people, you holding the meter leads while someone else is springing the switch and holding it to start. Measure the circuit with the meter while the switch is sprung to start and the solenoid is hooked up. You will find the problem then.

 

[rusty ol ranger]

Bad connection somewhere. Electricity is just like a garden hose with a kink in it. The kink is the poor connection. Just like the garden hose has plenty of pressure with the kink, until you open the nozzle and it fizzles out, your start wire is the same. Don't use it (meter uses just about nothing) and you have 12v. Go to use it (hook the solenoid up) and the voltage drops to zero, just like the garden hose fizzles out with the kink in it.

The trick is to leave the load on the wire, and THEN start checking places with the meter. In this instance it may take two people, you holding the meter leads while someone else is springing the switch and holding it to start. Measure the circuit with the meter while the switch is sprung to start and the solenoid is hooked up. You will find the problem then.

So since i dont have any power between the safety switch and solenoid wire thats probably the best place to start huh?

 

[franklin2]

You will not be sure where you have power and where you do not have power till you check it with everything hooked up and the switch held over to the start position. You never know, in that position you may not even have power at the ignition switch. Just keep working back till you get 12v with the switch sprung to start.

This is the reason why when working on certain vehicle circuits, a testlight works better than a meter. The testlight presents more load to the circuit which will drag the circuit down if it has a problem. A meter, especially a digital one, does not present hardly any load at all. I have been watching some of the troubleshooters on youtube, and at certain times they have their own headlamp bulb rigged up as a test light with test leads on it. The headlight bulb will draw several amps, loading the circuit down to bring any bad or iffy connections to the surface.

 

[scotts90ranger]

Yeah, that, and make sure the solenoid mounting plate has a good ground source since that's part of the equation, but if the voltage is going to 0 then there isn't enough amps getting through the ignition switch or something...

 

[rusty ol ranger]

Alright, ill try these things and keep yall updated

 

[superj]

you could probably drop a ford solenoid on there in place of the single post and wire it up like a truck. i did my riding lawn mower that way with a push button start when the ignition switch went out on it.

 

[ford4wd08]

You will not be sure where you have power and where you do not have power till you check it with everything hooked up and the switch held over to the start position. You never know, in that position you may not even have power at the ignition switch. Just keep working back till you get 12v with the switch sprung to start.

This is the reason why when working on certain vehicle circuits, a testlight works better than a meter. The testlight presents more load to the circuit which will drag the circuit down if it has a problem. A meter, especially a digital one, does not present hardly any load at all. I have been watching some of the troubleshooters on youtube, and at certain times they have their own headlamp bulb rigged up as a test light with test leads on it. The headlight bulb will draw several amps, loading the circuit down to bring any bad or iffy connections to the surface.

I know people that use a 12V back up alarm as a test light as well. Gives more load.

 

[scotts90ranger]

you could probably drop a ford solenoid on there in place of the single post and wire it up like a truck. i did my riding lawn mower that way with a push button start when the ignition switch went out on it.

I did that on my old riding mower, no idea what was wrong with the original wiring (too many safties and I was over using a "starter wrench" IE jumping the relay with a wrench...) with a $11 Amazon waterproof push button and a $7 riding mower starter relay. The cheap relays have one wire so you power that one then ground the mounting bracket and run the two high amp wires and bob's your uncle... it's just a little smaller than the Ford units and about 87 options for $7...

 

[rusty ol ranger]

I was thinking of using the ford solenoid if i needed one but wasnt sure what to do with the extra post terminal. Plus the right one is cheaper lol.

Im just trying to keep it original...im kind of a stickler about that. Its pretty unmolested and im trying to keep it that way. So id rather not go the push button route.

 

[Snoranger]

I was thinking of using the ford solenoid if i needed one but wasnt sure what to do with the extra post terminal. Plus the right one is cheaper lol.

Nothing… you would do nothing with the extra post. The extra post on the old Ford solenoids was an output when cranking (isolated from the main output).

 

[4x4prepper]

You can use a Ford relay to by pass the starter relay, I just did it to help diagnose a non-starter lawn tractor bought at auction.

--> BUT, what you should know is that riding lawn mowers - tractors use a starter relay that is not grounded through the case. It is grounded on one of the smaller terminals and the ground is only completely through the (negative) seat circuit. So, if you are not in the seat for safety reasons, the engine stops. This prevents you from starting it up with the blades engaged and cutting off toes or having it race away, or worse falling off and being run over by the implement you are towing. It helps people from winning the Darwin award.

Usually the negative for the ignition module and starter relay go through these circuits - seat -brake pedal on- implement control (off). That is the starter circuit, if the seat circuit is broken, lost of ground, then the ignition coil shuts off.

I have been buying these on E-Bay, I try to buy STENS as the base line minimum for quality.

Stens 435-099 Starter Solenoid for 740207 03551000 1-513075 532146154 GY00185 | eBay

Find many great new & used options and get the best deals for Stens 435-099 Starter Solenoid for 740207 03551000 1-513075 532146154 GY00185 at the best online prices at eBay! Free shipping for many products!

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If you had actually posted a picture, it would have given me an idea on what your relay is, since I have not seen a single post one, but, I suspect the post you feed (+) to is suppose to get (-) instead. It would help if I could see if you have a 4,5, or 6 connector on the ignition switch.

If you have (2) posts for battery cables and then a single post for a much smaller wire, that much smaller wire is probably for ground. I have never seen a seat safety switch with a positive circuit.

Oh course, on an older RE Snapper the only safety switch is between your two ears.

 

[rusty ol ranger]

You can use a Ford relay to by pass the starter relay, I just did it to help diagnose a non-starter lawn tractor bought at auction.

--> BUT, what you should know is that riding lawn mowers - tractors use a starter relay that is not grounded through the case. It is grounded on one of the smaller terminals and the ground is only completely through the (negative) seat circuit. So, if you are not in the seat for safety reasons, the engine stops. This prevents you from starting it up with the blades engaged and cutting off toes or having it race away, or worse falling off and being run over by the implement you are towing. It helps people from winning the Darwin award.

Usually the negative for the ignition module and starter relay go through these circuits - seat -brake pedal on- implement control (off). That is the starter circuit, if the seat circuit is broken, lost of ground, then the ignition coil shuts off.

I have been buying these on E-Bay, I try to buy STENS as the base line minimum for quality.

Stens 435-099 Starter Solenoid for 740207 03551000 1-513075 532146154 GY00185 | eBay

Find many great new & used options and get the best deals for Stens 435-099 Starter Solenoid for 740207 03551000 1-513075 532146154 GY00185 at the best online prices at eBay! Free shipping for many products!

www.ebay.com

If you had actually posted a picture, it would have given me an idea on what your relay is, since I have not seen a single post one, but, I suspect the post you feed (+) to is suppose to get (-) instead. It would help if I could see if you have a 4,5, or 6 connector on the ignition switch.

If you have (2) posts for battery cables and then a single post for a much smaller wire, that much smaller wire is probably for ground. I have never seen a seat safety switch with a positive circuit.

Oh course, on an older RE Snapper the only safety switch is between your two ears.

Mine dont have a seat switch just the blade switch. Im hoping to get a chance to wrench more on it this week