CV740 wiring help

Jon Hubert

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Hi guys. I'm in need of some electrical help. My 2013 Scag Cheetah has had intermittent problems since day one.... Sometimes I can mow almost the whole season without issue but it keeps coming back. So far it has completely drained a battery (without the key being in it), it has shut off while mowing at full speed twice, it has not restarted upon those shutoffs until it sat a few hours. And many occasions it hasnt wanted to cold start either...so I wiggle all the safeties (which Ive replaced full sets twice in hopes of throwing out the bad) but still nothing. I just wait till tomorrow and then it will start. I dont know what else to do but ditch the factory harness/safety interlocks and what have yous and go with simple inline fuse/toggle switch setup. I dont need the ammeter but Id like to keep the hour meter. So from the motor harness I get:

Green wire that looks to be grounded to carb cap.
Red wire that goes to bottom of carb (fuel shutoff maybe?)
Blueish-purple wire comes from center of rectifier and Im told recharges battery with 12volts
White wire which I read is a kill wire?
Blue wire comes out of plug and goes to starter pole instead of into rubber tube and up into engine (trigger wire for starter?)

Ill try and post a pic. If someone could tell me what condition each of these need and the simplest way to do it Id be forever grateful. I dont even need a key. A momentary push button is fine. Its way off the road locked up in a garage and Im not a commercial guy. So it doesnt go anywhere....except to the dealer for them to assess it and say it wouldnt do it for them. :thumbdown:


scag.jpg
 

bertsmobile1

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What you do is to check the wiring , find the problem & rectify it.
Only 2 ways for the battery to drain while engine is off.
1) rectifier with a bad diode
2) ignition switch faulty

The rectifier will eventually kill the alternator stator and continue to drain the battery unless you physically disconnect the battery when not in use.

A sudden loss of power will cause the fuel solenoid to shut off and thus the motor stop
Bypassing the mowers loom will not stop this happening.

A wire that is broken & just touching will burn out the rectifier as will a bad ground.
Bypassing the loom will not rectify a bad ground.
 

Jon Hubert

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Actually one of the ideas the dealer threw at me while still under warranty was a new ignition switch. They handed it over and I took it home to install. When I popped off the console panel it appeared they had it right because the spades on the backside looked like they took a hard hammer hit from the side. The harness plug was all splintered and flattened over to the side but the connections seemed to still be intact. I put it together and sure enough it fired right up. Then over the winter the battery crapped out. Sat maybe 3-3.5 months in the garage with no key in it. Maybe a fluke? I don't know for sure but something drained that battery. Then that following summer it did the sporadic no cold start yet two times that it did work fine it shutoff while mowing. I've replaced safety interlocks to the point I want them gone to rule out possibilities. I realize it's probly not popular to do this but I'm not savvy enough with a multimeter and after spending 8,200$ I'd like to get some reliable use out of this thing. I'll take the risk, my lawn is pretty level, I only mow when it's dry out, and at roughly 70 hrs on the meter I figure it owes me about 8k yet. The grounds are all stacked on one motor mount bolt and there's no visible corrosion. I clean it with my leaf blower, not the water hose.
 

bertsmobile1

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If the plug behind the switch was like that it shows some serious abuse before you got your hands on it.
Hassle the dealer for a new plug as it should have been a warranty / pre delivery fix.
The switch should connect the B ( Battery ) wire to the A ( Alternator ) wire when on & disconnect them when off to prevent the alternator back powering and trying to be a really bad electric motor.
Discharging over 3 months is what the fuel solenoid will do to a good fully charged battery
Some hour meters will also kill a battery over time.
 

ILENGINE

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Lets try this. Remove the negative cable from the battery. Put your meter on amps to start and connect the red lead to the negative battery cable, and the black lead to the ground terminal to the battery. Read the amperage, with the key on and off. if that reading is really low then move the meter to mA range and retest. Amp drainage with the battery off shouldn't exceed 100 milliamp. Or .1 amp. If the reading is 0 with the key off then there isn't anything draining the battery with the key off.

Normal reading should be less than 100 milliamp with key off and around .4-.5 amp with the key on but not running.
 

Jon Hubert

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I appreciate your assistance but I'm afraid my frustration took me past the diagnostic realm the other day. I removed everything that scag made wiring-wise and made a new replacement panel already where I will consolidate to just a momentary push button start, kill switch, pto switch, and choke/throttle levers (already milled out the slots and mounting holes for the two levers). I will also relocate the hour meter to a place where you don't have to flip up the seat and use an inspection mirror to view.... Was the pic I added viewable?
 

Jon Hubert

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I got it all together and mowed with it this weekend. Worked just like it should've from day one. I'm not sure if the way I hooked it up will draw on the battery or not but Ill run the test procedure for amp and milliamp draw later this week. Some things I noticed where the clutch engagement sounds much more crisp. Its a higher pitched shorter duration squeel and really to me sounds like its more efficient (less slip time). Also when Im done mowing I always cut it back to maybe 1200rpm or so on the drive back to the shed and let things calm down. It used to let out one really loud backfire, and now after mowing the yard back down in short increments over the weekend each time I put it away it sounded much more like a quiet pfff like when you light up your gas grill. So maybe it was a ground problem since it seems two circuits have maybe "improved"?
 
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