SCAG TIGER CAT ELECTRICAL PROBLEM

[2Peter119]

My machine is a 2010 Scag Tiger Cat (48") with about 800 hrs. Machine initially would not start and now is burning out electrical components. Been working on it for about a month (grass is getting pretty long). Here is what I've done so far:
1--- New battery
2--- Checked and cleaned all terminal connections (verified good contacts by ohm and volt meter)
3--- New starter solenoid
4--- New ignition switch
5--- New PTO switch (twice)
6--- Replaced (twice) same 20 amp fuse
7--- New voltage regulator
8--- Bypassed ignition relay.
9--- Checked ECM (good ground from green/black wire)

Initially, engine starter circuit was simply sporadic. Turning starter switch would not always immediately charge starter solenoid. This is pretty common in this humid environment and I either disassemble switch and clean contacts or replace switch. The problem worsened until engine would not start. No power thru green/white wire. Replaced starter switch after checking all contacts (no improvement). Did normal things as noted above. Made simple jumper wire to start engine (hot pole on solenoid touches to green/white wire terminal for coil). Then engine quit while mowing. Battery not charging. Stator @ 29 vac and all connections good. Replaced voltage regulator. Charge back to 14+ vdc. Back to mowing. Blew 20 amp fuse. Replaced fuse. Mowed for about an hour and PTO switch went bad. Ordered new PTO switch. While waiting for new PTO switch, worked on ignition system. Although I could hear the ignition relay (with diode) click when trying to start engine, contact between red/yellow and green/white wires was not happening (ohm meter). Ordered new ignition relay with diode. PTO switch arrived and installed. Until the new ignition relay comes, I installed a simple spring return on-off switch between red/yellow and green/white wires to eliminate need for jumper @ starter solenoid. Engine started right up. Drove around for about 15 minutes then started to mow. Blew PTO switch in first half hour. More than a little frustrated. Suspect internal wiring in electric clutch but figure problem began with the starting circuit (clutch disengaged). Sorry to carry on so but I just read posts on electrical problems and figured the more information provided would save some time. I did get under the clutch but didn't see any chafed wiring. Sure appreciate any advice

 

[2Peter119]

I think I've solved the problem: going thru similar threads, there were a couple which suggested checking the resistance across the electric clutch coil. Don't have the thread handy but, as I remember, the resistance should be in the range of 2.5 - 3.5 ohms. Mine checked in at less that 0.6 ohms. With this low resistance, the amp draw may have been sufficient to both blow the 20 amp clutch fuse and, failing this, destroy the PTO switch. Not sure if the failed rectifier and ignition coil had anything to do with this. Ordered new clutch and PTO switch and will comment if problem goes away.

 

[mechanic mark]

Good post, after installing new PTO clutch be sure to burnish clutch. If you do not have an operators manual google: Scag manuals with your serial number handy. If burnishing procedure is not in manual just google: installing new PTO clutch & burnishing procedure, this is very important.

 

[Joe2]

I had the very same issues with a Scag Turf Tiger. 35 HP briggs, kept blowing fuses, burning up PTO switch, etc. After reading threads on this site about checking clutch ohms, I did and had .4 UGH. Bit the $500 bullet and bought a new clutch, checked ohm's prior to install and no more problems :thumbsup: FYI regarding burnishing, my new clutch had a tag that stated it was burnished at the factory and not needed. Thanks again all

 

[mechanic mark]

Good deal! Wonder if 2Peter119 got his going?

 

[2Peter119]

Sorry to take so long in replying. Last post pretty much summed up my experience. Ohms across existing clutch coil read 0.60. Replaced clutch ($368) thru Amazon. Appreciated the comment on burnishing the clutch but as with the last post, the new clutch came with a tag stating that the burnishing was done at the factory and not to burnish. Took about an hour to remove old clutch and install new. Checked ohms at new coil (2.5 ohms). This would reduce the amp draw by about 75% and eliminate the blown fuses/fried PTO switches. Started machine up and mowed for the rest of the day. Something to consider: The PTO switches cost about $17 bucks at Amazon. These switches can be found on a lot of different machines, not just Scags. Although I had one on order with the clutch, I found one on a junked Crosman riding mower when I took the trash to the dump. Doesn't even take any tools to remove. Thanks again for all the help.