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Tiger cub blowing ignition fuse

#1

S

srw101

Hello all, I'm having an issue blowing the 20 amp ignition fuse and hope someone can shed some light before I drop big bucks on what might be a simple problem. My safety circuit is shorted to ground which instantly blows the fuse when I turn the key on. I traced the circuit all the way back to the orange wire of what I believe to be a safety relay module of some sort. when I remove the connector I no longer have a short to ground but I can't be sure the short is taking another path once I plug it back in. Can anyone verify that this isn't supposed to be grounded? Thanks for anything...I'm pretty desperate, grass is gettin tall!




Scag Tiger Cub STC
21 horse Kawasaki
48 inch cut


#2

B

bertsmobile1

The safety circuit IS A GROUND CIRCUIT.
It is not short to ground it is either open =running or ground = stopped.
The power circuit only goes to the starter motor , the PTO & the carb soenoid.

SO

1) how much of the stuff they taught you i high school did you actually understand
2) what gear do you have to work through the wiring with
3) Exactly what happens from the second you bum hits the seat, in painful detail


#3

B

bertsmobile1

The safety circuit IS A GROUND CIRCUIT.
It is not short to ground it is either open =running or ground = stopped.
The power circuit only goes to the starter motor , the PTO & the carb soenoid.

SO

1) how much of the stuff they taught you i high school did you actually understand
2) what gear do you have to work through the wiring with
3) Exactly what happes from the second you bum hits the seat, in painful detail


#4

S

srw101

bertsmobile1 said:
The safety circuit IS A GROUND CIRCUIT.
It is not short to ground it is either open =running or ground = stopped.
The power circuit only goes to the starter motor , the PTO & the carb soenoid.

SO

1) how much of the stuff they taught you i high school did you actually understand
2) what gear do you have to work through the wiring with
3) Exactly what happes from the second you bum hits the seat, in painful detail
Click to expand...

it's the only ground that i can find running to the other side of the fuse. I do understand that short to ground equals blown fuse and that's what I'm dealing with as soon as I turn on the key. Really don't need to mock me to get your point across I'm doing the best I can to figure this out. In painful detail, the fuse blows when I turn the ignition switch on and to your point if the safety circuit is grounded wouldn't that blow a fuse if the two were to meet? Solenoid unplugged, motor harness unplugged, clutch is unplugged.
I have two fluke meters and a test light, I'm not an expert but I am familiar with ohms law. 0 ohms of resistance from neg battery post to one side of the fuse. Thanks for your help.


#5

B

bertsmobile1

No one is trying to mock you and the accidential double post has been removed.
Electricity confuses a lot of people because they learned how to answer questions not how things work.

OTOH you have the mower in front of you & we have nothing but words on a screen.
You specifically said your SAFETY circuit was grounded.
Mowers have 3 circuits
1) safety ( ground circuit )
2) cranking ( power circuit)
3) charging ( includes electric PTO's ) which is also a power circuit

Then only thing that gets power in the on position on every mower ( assuming the PTO is off ) is the carb solenoid.
Some also bring the rectifier into circuit.
SO

start by unplugging the mower to engine plug ( might be 2 of them )
if the fuse blows then the problem is in the mowers wiring
If the fuse does not blow the problem is in the engines wiring.

If you want us to walk you through it that is fine but you will need to find the circuit diagram for your mower and post it.
To do that you need to have posted 3 times ( spam prevention )

as previously mentioned, you have the mower in front of you and you have all of the required model & serial numbers needed to get the correct wiring diagram
We have no more that what you tell us.


#6

S

srw101

bertsmobile1 said:
No one is trying to mock you and the accidential double post has been removed.
Electricity confuses a lot of people because they learned how to answer questions not how things work.

OTOH you have the mower in front of you & we have nothing but words on a screen.
You specifically said your SAFETY circuit was grounded.
Mowers have 3 circuits
1) safety ( ground circuit )
2) cranking ( power circuit)
3) charging ( includes electric PTO's ) which is also a power circuit

Then only thing that gets power in the on position on every mower ( assuming the PTO is off ) is the carb solenoid.
Some also bring the rectifier into circuit.
SO

start by unplugging the mower to engine plug ( might be 2 of them )
if the fuse blows then the problem is in the mowers wiring
If the fuse does not blow the problem is in the engines wiring.

If you want us to walk you through it that is fine but you will need to find the circuit diagram for your mower and post it.
To do that you need to have posted 3 times ( spam prevention )

as previously mentioned, you have the mower in front of you and you have all of the required model & serial numbers needed to get the correct wiring diagram
We have no more that what you tell us.
Click to expand...
My apologies, I reread my post and I did say safety circuit was a deadshort. Now I feel like an *** lol:tongue: Anyhow I'd unplugged all except the main two wires that lead to the solenoid earlier in the day. Verified that they were leading to the fuse and one side of fuse was hot and was the only path. With fuse out other side of fuse holder was dead short and as I said before this lead to the keyswitch which in on position to safety circuit. I tried to find a electrical diagram of key switch to see what the switch contacts were closed in on position but I just found pictures, no prints. I'll post diagrams as soon as I can. thanks again


#7

L

Luffydog

Have you looked under the key switch panel for a bad wire.


#8

S

srw101

STC48A21kA electrical diagram.jpg


#9

S

srw101

Luffydog said:
Have you looked under the key switch panel for a bad wire.
Click to expand...

Yes and everything seems fine, no chaffed wires no loose connections to speak of.


#10

L

Luffydog

What engine do you have


#11

S

srw101

Luffydog said:
What engine do you have
Click to expand...

The sticker says

FH641V-BS18

Which I think is the 21 horse Kawasaki


#12

B

bertsmobile1

srw101 said:
The sticker says

FH641V-BS18

Which I think is the 21 horse Kawasaki
Click to expand...

Did you get and print out the wiring diagram SRW101 posted for you ?
If so do the colours correspond to what you have on your mower?

So the next step is to look under the dash at the key switch for a loose wire then reach in and pull the plug off the back of the key switch.
The terminals should have tiny letters cast into the back.
The power in wire ( red/Yellow ) on the B terminal should not be connected to anything in the off position.

In the off position the G = ground wire should be connected to the M = magneto wire
Nothing else should connect to the G terminal and nothing else should show a dead short to ground so test them all.

On the back of the key switch should be
B=Battery
M=magneto
G=Ground
S=Start
Then an ON
position Usually marked A
and a lights / accessory / recharge marked A2 or L.
If the output side of the fuse on the power feed wire from the solenoid hot cable is ground with the 2 engine plugs undone then you have a short in the mowers wiring
Using diagram from SRW101 the relay should not be energised unless the key is in the start position and the same for the safety switches .
This leaves you with the hour meter or the module plus the wiring between them.


#13

S

srw101

bertsmobile1 said:
Did you get and print out the wiring diagram SRW101 posted for you ?
If so do the colours correspond to what you have on your mower?
Click to expand...

1. I'm the OP (srw101) so I'm the one who posted the schematic. There area actually a few of different versions of these schematics floating around on the interwebs but the one I posted is easiest to read and comprehend.

2. The colors all seem to correspond to the drawing albeit mine are faded and harder to I.D.

3. My IGN switch doesn't have any letters stamped on it but because the wiring harness is modular I'd say it has to be right.

I ordered an ignition switch so my best guess right now is that there are some contacts making when they shouldn't be within the sw. Plus this is by far the cheapest route, I'll report back if this clears it up. Thanks again.


#14

L

Luffydog

Also could be the relay as well key switch or fuel solenoid had one doing the same thing about 2wks ago but can't remember right was the problem


#15

S

srw101

Luffydog said:
Also could be the relay as well key switch or fuel solenoid had one doing the same thing about 2wks ago but can't remember right was the problem
Click to expand...

I'll unplug the solenoid and see what happens. thanks for the suggestion!


#16

B

bertsmobile1

srw101 said:
1. I'm the OP (srw101) so I'm the one who posted the schematic. There area actually a few of different versions of these schematics floating around on the interwebs but the one I posted is easiest to read and comprehend.

2. The colors all seem to correspond to the drawing albeit mine are faded and harder to I.D.

3. My IGN switch doesn't have any letters stamped on it but because the wiring harness is modular I'd say it has to be right.

I ordered an ignition switch so my best guess right now is that there are some contacts making when they shouldn't be within the sw. Plus this is by far the cheapest route, I'll report back if this clears it up. Thanks again.
Click to expand...

Sorry, that seemed to have eluded me.
Most mowers made since the 70's have a gang plug on the ignition switch although some use a seperate short ground wire which is not in the main loom.
However the switches are still labeled .
the characters are very small.
Some are on the pins while others are on the base.
Did you check the back of the plug with a magnifier ?

In cases like yours I like to pull the plug then jump the terminals on the plug to determining if it is the switch or the wiring.
You can do the same thing with the relay base.

Switches do go bad, they rust inside and one poster with a similar problem ended up finding the problem was ants inside the switch itself


#17

S

srw101

bertsmobile1 said:
Sorry, that seemed to have eluded me.

Switches do go bad, they rust inside and one poster with a similar problem ended up finding the problem was ants inside the switch itself
Click to expand...

Just when you think you've heard it all:tongue:


#18

L

Luffydog

Check the electric fuel management control if equip


#19

L

Luffydog

Just looked back at first post and noticed it is a ka and not a bs engine


#20

jekjr

jekjr

I had a Tiger Cat with the 22 HP Kawasaki engine that had problems blowing the 20 amp fuse perpetually from the time it was about a year old. It might run a day and not blow one and then it might blow several a day. Tried numerous things before it went out of warranty and then after it went out. Finally one day I had the dealer install new fuse holders on it and it has run several hundred hours since then and has not blown another fuse. The ones on it did not physically look bad. Just food for thought.


#21

S

srw101

I finally fixed my Cub! I replaced the key switch and the relay also but the safety module is what finally brought her back to life. I definitely didn't want to replace the wire harness for over $200 so I removed the harness, cleaned and inspected all the connectors rang the wires out and deemed it good. I'm Glad I replaced the relay because now it starts up so much faster! Thanks for all the help I guess I just had to stick with it until something worked:biggrin:


#22

A

AMM1869

I wish I was able to trace mine down. Replaced a brand new battery, shorted out 2, 20 amp fuse's and pto switch, shorted out. Not all at one time but over the course of 3 months. Then after replacing the pto switch and mowing about 5 minutes, added fuel, engine off, gas fumes exploded on left side, burned up left side of Cub ! I contacted Scag and my local dealer was interested in problem also, sent all of them photos. Best I can determine something electrical was hot/shorted and ignited fumes.


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