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Hi,

I have a 2014 Scag Cheetah which won't even crank. All safety cut outs appear to be ok but, in checking forums, it seemed to me the problem may have been Relay 483013 near the choke control or maybe the Electronic Control 483599. However I've replaced these and the Scag still won't crank.

In one post "2004 Scag Tiger cub 48" won't start/won't crank" it states attaching a wire from the battery earth to the Relay will bypass the safety checks and allows the Scag to start. This works fine on my machine however, as soon as I release the brake or move a steering arm or start the cutting deck, the motor cuts out.

Does anyone know, precicly, what the Electronic Control checks to make sure the mower is good to go. Clearly something electrical isn't right but I've no idea how to fault find the issue.

TIA - Peter

Hopefully someone that knows will post something for you soon. A wiring diagram should show the starting wiring circuit and the path voltage travels to get to the starter. I don't have a wiring schematic. When the switch is turned to start the hot wire travels to satisfy all the OSHA switches before powering the starter. On the Scag there are many OSHA switches to protect us; emergency brake, seat, mower, handles ect.

My 2015 Scag Cheetah with Kawasaki motor will sometimes not do anything when I turn the key to start. I have so far been able to solve the problem temporarily without using a volt meter. I have jiggled and moved OSHA switch stuff until the unit starts. Once is starts, all is good.

I have determined that my OSHA switches that are causing me problems are the seat and the emergency brake. So now when it acts up, I mess with those first and it starts right up. I work the brake back and forth and bounce on the seat. Some day I may have to follow the battery power wiring to see which switch is not allowing the voltage to go to the next OSHA switch and ultimately the starter.

I would not want to tell anyone how to bypass these safety switches or how to jump past them from the battery directly to the starter.

My brother in law can fix anything. He always says to just follow the battery voltage and see where it stops. When you find where it stops, there lies the problem. This advice has served me well.

Again there are a bunch of folks that know much more than me. Maybe one will check in before spring to help you. I hope I have not wasted your time. Please let us know what you find out. Good luck.

Hi,

Thanks for the comment and, yes, "ollow the voltage" does sound like good advice. If I can't get more detailed help that's what I plan on doing - by dropping the Scag off at an auto-electrician! I'm a bit reluctant to do that though as I can just see it costing a pile of money.

I messed around with the seat sensor and eventually just bridged the connectors so that it's always "on". I've also wiggled the brake and steering arms sensors all to no avail unfortunately. I have also put a meter on each of the micro-switches and manually activated them and they work fine.

I hope I don't have to wait until spring - I'm in Australia and its summer here and my 5 acres of grass is waaay to long. The Scag been out of action for a month (waiting on parts from the US).

Cheers, Peter

Hi,

A p.s. to my previous post...

I guess what I'm looking for is just what the Electronic Control is looking for to start and keep running, e.g. the white wire comes from the brake and must have voltage, the yellow comes from the seat and must have voltage.

With this information even I would have a chance of finding and fixing a problem, certainly an auto-electrician should.

BTW - I do have the circuit diagram from the Scag parts list but doesn't say what "state" the circuits have to be in to allow the Scag to start.

Cheers, Peter

Your operators manual will tell you what conditions need to be met for engine cranking/starting.
On the wiring diagram, you need to trace the circuits as in follow the voltage and check the machines electrical harness for voltage at locations to find where the problem is.
The electronic control module senses voltage present or absent in its program and allows or denies cranking and or starting.
I suggest that you start troubleshooting with a fully charged battery that has clean connections and inspect the electrical connections (grounds/earths) that are installed on one of the engine mounting bolts.
Then setup the machine for engine starting such as travel levers moved outboard, parking brake on, PTO switch in the off position and the operator presence switch (seat switch) closed.

Hi,

Thanks for the responce.

Are you able to throw any light on what the electronic control module (ECM) is looking for to allow cranking? I was hoping I could fault find at the ECM and work back from there.

I've very little electrical knowledge but, would someone familiar with circiut diagrams, be able to look at the electrical schematic in the parts list and deduce what lines, into the ECM, need to have / not have voltage to permit cranking?

BTW - I have charged the battery and removed and cleaned all grounds/earths at the engine block.

Cheers, Peter

Provide your machine model and serial number so I can find the wiring diagram for your specific machine.
The Scag website has current and older model info available in the manuals section.

PeterJones said:

Hi,

A p.s. to my previous post...

I guess what I'm looking for is just what the Electronic Control is looking for to start and keep running, e.g. the white wire comes from the brake and must have voltage, the yellow comes from the seat and must have voltage.

With this information even I would have a chance of finding and fixing a problem, certainly an auto-electrician should.

BTW - I do have the circuit diagram from the Scag parts list but doesn't say what "state" the circuits have to be in to allow the Scag to start.

Cheers, Peter

Click to expand...

WRONG WRONG WRONG WRONG.
There is no power anywhere except in the cranking circuit all of the rest are ground circuits so will be either open or ground.
The magneto works when the control wire is open circuit, when it is grounded it stops.
If any of these wores ever gets battery voltage then the magneto contol modules will get fried and they are very expensive.

Get a wiring diagram, it really does not matter too much what ZTR mower it is from because they are all BASICALLY the same.

If you have to take it somewhere , find a real mower repair shop, one that repairs mowers & sells used mowers, not new ones.
An auto electrician will not have the experience or informstion on hand to repair your wiring in a timely mannar at a reasonable price.

Hi,

Thank you for both responses. My unit is a: SCZ52V-28BS with serial number H7200089.

Thanks for explaining that the wires are ground circuits (whatever that means) but I certainly understand that no voltage is used. I take the point that a lawn mower repair shop is the best option rather than an auto-electrician.

Is it possible for me to test the wires going into the ECM and determine what their state is, i.e. either open or ground? If so, is it then possible for me to determine, from the wiring diagram, if the state is "correct" to permit the engine to crank? If the answer to these questions is Yes does anyone have the time and inclination to provide further information on how to physically test each wire and how to read the wiring diagram - perhaps a simple example using the brake sensor.

Cheers, Peter

Hi PeterJones,
Thank you for posting your machine info.
As your Cheetah has a Briggs & Stratton engine, there is a remote starter solenoid that is electrically located in the battery positive cable (red cable), between the battery positive terminal and the starter motor on the engine. There is a green/white stripe wire connected to one of the small terminals on the solenoid. This wire comes from the cranking relay that is close to the key switch. When all the cranking safety circuits are correctly setup, (PTO switch in off position, travel levers outboard, parking brake on and the operator position switch (seat switch) actuated, power from the key switch in the starting position will be sensed at the ECM and the cranking relay and the ECM will provide a ground to the cranking relay thru the black/green tracer wire which will allow voltage to actuate the starter solenoid thru the green/white stripe wire.
The first thing I would do is to check the fuses in both the red wires and the yellow wires. If the red fuse has blown then nothing will work electrically. The fuse in the yellow wire is for the engine charging system output.
A quick check of the starter solenoid is to first make sure that the machine will not move if the engine starts, disconnect the green/white wire and with a test jumper wire, jump from the red positive battery terminal to the terminal where the green/white wire was connected. This will tell you if the solenoid and starter motor are functioning.
Let us know how things test for you.:laughing::biggrin::smile:

In your operators manual, pages 74, 75 and 81 are the electrical system for your Briggs & Stratton powered Cheetah.

Hi Guys,

From what bertsmobile1 said it looks as though I have a serious issue and need to take the Scag to an electrician. I have 12v on the brake, steering arms and seat switch wiring as soon as the ignition is turned on!

Cheers, Peter

First an appology.
I should have checked first, It appears that Scag do things different to everyone else.
They run power all over the mower.

go to Scag http://www.scag.com/OPManuals/SCZ/SCZOPMANTOC.html and download your manual.
In the back is the wiring diagram and according to the one I checked Scag safety switches are live.
The SCAG EYE has a chip in it by the looks of things which grounds out the control wire to the relay which powers the starter solenoid which cranks the engine.


The last place you should take the mower to is an auto electrician.
Take it to a mower shop
Mower wiring is very easy.

Check the wiring according to the diagram for your mower.
If you can not understand it post your numbers so we can bring up the same wiring diagram and walk you through it.
I will go back & try to remove my erronious reply.

Hi Bertsmobile,

Well that's a relief I must say - I was thinking that the Scag's electrical system was toast!

Thanks for the offer of phone consult - very very much appreciated. I see that you are in Australia which is bonus - phoning the US at a convenient time, as you may know, is sometimes difficult to arrange.

Please e-mail me at jonespm@ozemail.com.au with your phone number and a date/time convenient for you and I will call. When I say "I" I really mean my son-in-law, James Deacon - he's the mechanical wiz at our property (Hahndorf, SA) and he will understand what you say better than I.

Cheers, Peter

Hi Guys,

Problem fixed. In my case I had no power to brown (seat power) wire into the Control Module. This was just a loose connection in the main harness plug!

What I did deduce are the conditions the Control Module is looking for to allow cranking (all measurement at wires going into the Control Module):

• Control Handles Out, Brake On, Seat Switch Depressed, key in START position.

• The RED wire at the module provides BATTERY VOLTAGE to power-up the module - needs 12 volts

• The BLACK wire at the module provides GROUND to the module. Confirm good GROUND is present on BLACK wire at module connector.

• The ORANGE wire at the module is supplying BATTERY VOLTAGE from the LH & RH neutral (control lever) switches to the module- needs 12 volts

• The BROWN wire at the module is supplying BATTERY VOLTAGE from the seat switch to the module - needs 12 volts

• The PINK wire at the module is supplying BATTERY Voltage from the brake switch to the module - needs 12 volts

• The LT BLUE wire at the module is supplying BATTERY VOLTAGE from the PTO switch to the module - needs 12 volts

• The GREEN/BLACK wire at the module is supplying GROUND from the module to the start relay. Confirm good GROUND is present on GREEN/BLACK wire at the START RELAY.

• The GREEN wire at the start relay is supplying BATTERY VOLTAGE from the key switch to the start relay - needs 12 volts

When the above listed conditions are met, voltage will be supplied on the GREEN/WHITE wire from the start relay to the starter solenoid to engage starter.

Cheers, Pete