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i am working on a Ferris 5900536 model number. unit will not start, i mean nothing. no power. all safety switch's replaced. Ignition switch replaced, this model has three relays ( what they are for i do not know. I do not know how to test them. No Power, nothing left to test, yes relays been replaced. I am thinking about rewiring it. I am Retired Sears Service Tech and Wards. has anyone had this problem?

Here is how to test relays.
To test a lawn tractor relay, you'll need a multimeter and a 12V power source, like a fully charged battery. First, identify the relay's terminals: typically, terminals 85 and 86 are for the coil, and 30 and 87 are for the switch. Apply power to the coil terminals (85 & 86), and a good relay will click. Then, check for continuity between terminals 30 and 87. A good relay will show continuity when the coil is energized (clicking) and no continuity when de-energized.


This is the procedure I use. Report back with your findings and we’ll work from there.

Electrical problems can be very easy or very difficult, depending on four things.

1. How well you understand basic electricity.
2. What tools you have and know how to use.
3. How well you follow directions.
4. You don't overlook or assume anything and verify everything.

Remember we cannot see what you are doing. You are our eyes, ears and fingers in solving this problem. You must be as accurate as you can when you report back. The two basic tools we will ask you to use are a test light and a multi-meter. If you have an assistant when going through these tests it would be very helpful. These steps work the best when done in order, so please don't jump around. Now let's solve this problem.

First, check the fuse(s), check battery connections for corrosion (clean if necessary) and voltage - above 12.5 volts should be good. Check and make sure the chassis ground is clean and tight.
Second, check for power from the battery to one of the large terminals on the solenoid. One of the wires is connected directly to the battery and has power all the time so one of the large terminals should light a test light or show 12 volts on a meter at all times.
Third, check for power at the small terminal of the solenoid while depressing the clutch/brake pedal and holding the key in the start position (you may need an assistant to sit in the seat to override the safety switch). If your solenoid is a four wire solenoid, check both small wire terminals as one is ground and the other is power from the ignition switch. If your solenoid is a three wire solenoid, make sure the solenoid body is not corroded where it bolts to the chassis of the mower as this is your ground path back to the battery. If in doubt, remove the solenoid and clean the mounting area down to bare metal. If there is no power to the small terminal then your problem is most likely a safety switch, ignition switch or in the wiring.
Fourth, check for power on the other large terminal of the solenoid while holding the key in the start position (you may need an assistant to sit in the seat to override the safety switch).
Fifth, check for power at the starter while holding the key in the start position (assistant again).
Sixth, check your ground circuit back to the battery.

After you have gone through each of the above steps, let us know what happened when you did each step. At that point we will have great info to tell you how to proceed. Remember you are our eyes, ears, and fingers, so please be as accurate as possible.

Be as specific as possible with voltage readings as this will help diagnose your problem quicker. If you do not know how to perform the above checks, just ask and I will try to guide you through it. Youtube also has some videos and as you know a picture is worth a thousand words.

Richard P Korf said:

all safety switch's replaced. Ignition switch replaced,

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All new parts, require, testing. New doesn't mean new these days. Put the credit card up and start testing what you have.

Richard P Korf said:

yes relays been replaced. I am thinking about rewiring it.

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Keep all your old parts. Most I'm guessing are good.

Pull out the sparky plugs. See if she cranks over.

Load test the battery. Check/clean/tighten power and grounds. Could be a simple key switch. Look for corrosion in the wiring connectors, switches and fuses.

A bad battery will fool a multimeter. I've had it happen before. Voltage will show good even with very poor amperage. Voltage is potential, Amperage is power to do the work.

I suggest you go back to your training that covered voltage drop testing. If you are not familiar with this form of testing, just ask.

Maybe some diagrams would help:

Auto Doc's said:

A bad battery will fool a multimeter. I've had it happen before. Voltage will show good even with very poor amperage. Voltage is potential, Amperage is power to do the work.

I suggest you go back to your training that covered voltage drop testing. If you are not familiar with this form of testing, just ask.

Maybe some diagrams would help:

PartsTree - Home of OEM Parts for Outdoor Power Equipment

Parts lookup and repair parts diagrams for outdoor equipment like Toro mowers, Cub Cadet tractors, Husqvarna chainsaws, Echo trimmers, Briggs engines, etc.

www.partstree.com

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No it is not battery, unit has power but the starter will not start unless you cross the terminals. has all new safety switch's. this unit has three resister that i have never seen on a mower before. Thanks Forum any way. I have worked on mowers since 1976 sears service wards service and Richards Repair since forever never had this problem. I have a Ferris for 5 years now no problem.

No it is not battery, unit has power but the starter will not start unless you cross the terminals. has all new safety switch's. this unit has three resister that i have never seen on a mower before. Thanks Forum any way. I have worked on mowers since 1976 sears service wards service and Richards Repair since forever never had this problem. I have a Ferris for 5 years now no problem.

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Did you ever go through the procedure I posted to pinpoint a cause?

think of the electrical flow like water in a pipe. Use your multimeter on the say 20V +/- range to move along the path to see where the voltage disappears. If it goes all the way to the solenoid, check it again while the key is turned. KEEP in mind that there are TWO paths for the voltage. They are the 12V+ path and the 12V ground path. We forget the ground path but problems can be there (e.g. - a bad ground cable, connection to the battery, a bad connection between the frame and engine, a bad connection between the starter and the engine). Also keep in mind that voltage is like water pressure. Amperage is like water volume.

Hi Richard,

Many of us have worked on equipment since the 70's and some earlier than that. We're not questioning your experience, but we've all be tricked once in a while. LOL. Welcome to the club.

Modern "new" parts often turn out to be junk right out of the box. Playing parts swap is not diagnostics, it's a shotgun fix approach that seldom works.

The stupidest one I have in recent memory was on a Husqvarna rider. It had a ground wire in the harness that doubled back from the right headlamp connector all the way back to the start solenoid. The ground wire got clipped off inside the harness loom and the start solenoid would not function because of it.

I have no idea where engineers come up with this kind of stuff.... It defies logic.

Have you searched any of the diagrams I attached in the Parts Tree link earlier? There are quite a few and they are different according to the serial number on your machine product label.

OP ghosted us all LOL.

Rivets said:

Did you ever go through the procedure I posted to pinpoint a cause?

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Don't want to be a trouble maker ....but of course not...BASICS!!! why spend money on parts you DO NOT NEED! Thanks for your always, ok 99% of the time spot on help...I have learned a lots from folks like you and the other well-seasoned veterans on this site. Be well Happy Cutting!

Great info here! I’m always amazed by ungrateful first time posters. Those that have responded, your efforts are appreciated as I know I’m still learning.

Unbelievable!

Some people live to work, some people work to live, while there are still many more who just watch from the outside and wonder why work at all.

A bad pto switch will not let the motor crank, just sayin.

Wire ends do break inside pto harness plug! Look closely and maybe you will see half the gold wire end missing.

A bad pto switch can be the problem or a broken wire end inside the pto switch harness. Look closely at each gold color wire end foe a 1/2 missing tab.