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I have a Swisher ZT2454 mower. It isn't starting and the fuse blows when I turn the key to 'start' (maybe just 'on'). I can power the solenoid and hear it click. I measured continuity on the wiring and it all seems OK. I tested from the PTO switch and ignition switches, reviewing wiring diagram and making sure that the switches were working properly. I replaced the regulator, starter, and ignition switch. I have no idea what to try next...

PTO should be Off, check seat switch for replacement.

Okay let's determine when the fuse is actually blowing. Is it when the switch is first turn to run or is it when you turn to start?

Got to stop throwing parts at it and do some real real troubleshooting.If it is just to run then unplug the hour meter and the PTO switch and recheck.

I do suspect a short in the wiring but got to trace which circuit it is in first and then hand trace that circuit.

Hi - thanks for responding. I checked the fuse today. It blows as soon as I move the switch to the ON position.

Regarding the parts, the ignition switch was a guess, since I didn't want to work on it... However, I then checked to the best of my ability the continuity of all the wiring, toggling all the switches and making sure that they were working right. At that point, I pulled out the regulator and tested it. I checked for resistance between the two yellow leads and there wasn't any continuity. I thought (maybe incorrectly) that meant that it was bad, so I ordered a new one. However, when I got the new regulator and tested it the same way, there was no continuity either. Therefore, I assumed I tested incorrectly, and decided I needed to check the starter. I planned on applying power and making sure it spun. Somewhat clueless, I unscrewed the bolts that hold the two ends of the casing together. There were three spring-loaded terminals that connected to shaft which came out when I disassembled it. I managed to get them back on, but I was pretty sure I broke it anyway. So I tested the starter after I put it together, and it didn't spin. So I ordered a new starter. So now you know my experience level...

Anyway, I have long suspected a short in the wiring, but I searched the wiring looking were it passes through a hole or anywhere it could be rubbing. Everything looks fine. I don't know how to properly test for a short, but I tried testing for continuity between various points and ground, but I didn't find any continuity.

As for unplugging the hour meter and PTO, are you asking me to unplug them just to see if the fuse blows? I didn't check anything with the hour meter. On the PTO I checked all the terminals to make sure it was switching properly and it seemed fine.

Thank you both for responding.

Okay since it blows when just turned. The only components in that circuit is the PTO (which if off is out). The hour meter, and the carburetor fuel solenoid. Also the wiring for the fuel solenoid can get pinched between the starter and crankcase thus causing a short. I kinda laying odds one of the last two being the problem. First try unplugging the carburetor solenoid and test for blowing fuse. Yes I understand fuse can be costly if purchased locally. You can use a test light in place of the fuse and if short present the bulb would light up. I would use something like a 1156 bulb and plug the two leads in as if it was the fuse.

Try unplugging the regulator.

hlw49 said:

Try unplugging the regulator.

Click to expand...

IF present is not in the run circuit.

StarTech said:

Okay since it blows when just turned. The only components in that circuit is the PTO (which if off is out). The hour meter, and the carburetor fuel solenoid. Also the wiring for the fuel solenoid can get pinched between the starter and crankcase thus causing a short. I kinda laying odds one of the last two being the problem. First try unplugging the carburetor solenoid and test for blowing fuse. Yes I understand fuse can be costly if purchased locally. You can use a test light in place of the fuse and if short present the bulb would light up. I would use something like a 1156 bulb and plug the two leads in as if it was the fuse.

Click to expand...

I unplugged the solenoid on the carburetor. Fuse still blows.
Unplugged the PTO switch. Fuse still blows.
Unplugged the hour meter. Fuse still blows, but I noticed that it didn't blow when I turned the switch to ON. However, when I turned the switch back to OFF, the fuse blew.
Ordered more fuses...

StarTech said:

IF present is not in the run circuit.
View attachment 68896

Click to expand...

Just so I understand - you're saying that since the regulator is not in the run circuit, it shouldn't cause a blown fuse even if it was faulty?

hlw49 said:

Try unplugging the regulator.

Click to expand...

I'll try it when I get more fuses tomorrow.

chris.wyse said:

Just so I understand - you're saying that since the regulator is not in the run circuit, it shouldn't cause a blown fuse even if it was faulty?

Click to expand...

Correct as according the diagram the regulator would connected directly to battery side of the starter solenoid. Fuse is on the side feeding the ignition switch to power the fuel solenoid, hour meter, (run and start positions) and the trigger wire for the starter solenoid (when in the start position).

So start by unplugging the engine to mower connection which should be near the starter motor
Fuse blows = wiring problem in the mower
Fuse does not blow = wiring problem in the engine

That is an old mower so a problem with chaffed wires is high on the cards and as you are coming out of winter also rat/mice nest is also high .

bertsmobile1 said:

So start by unplugging the engine to mower connection which should be near the starter motor
Fuse blows = wiring problem in the mower
Fuse does not blow = wiring problem in the engine

That is an old mower so a problem with chaffed wires is high on the cards and as you are coming out of winter also rat/mice nest is also high .

Click to expand...

Ok. The.problem is in the mower. Should i pull all the wires? I’ve already tested continuity so the short is probably chafed insulation that hasn’t broken the wire. Or do i test for continuity between ground and all ends of the wires individually?

Does the new switch have the markings shown in the diagram Star posted in reply # 7
If so make 3 jumpers with a male at both ends
Unplug the engine plug to avoid accidentially putting power onto the kill wire
Now according to the same diagram this mower runs the power to trigger the starter solenoid through the two lap bar switches via the green wires
1) So unplug both lap bar switches and jump the wires at the plugs then jump the B & S terminals at the key switch engine should crank .
2) IF fuse does not blow then jump B & L terminals , hour meter should start counting nothing else should happen
If fuse does not blow then plug the key switch and try both positions
IF fuse does not blow one of the lap bar switches is bad or the plug has a bare wire or even spiders web shorting it so plug one in and turn key then the other till fuse blows .
IF the fuse blows at step 1 then the lap bar switches are OK & the green wire has a short some where

bertsmobile1 said:

Does the new switch have the markings shown in the diagram Star posted in reply # 7
If so make 3 jumpers with a male at both ends
Unplug the engine plug to avoid accidentially putting power onto the kill wire
Now according to the same diagram this mower runs the power to trigger the starter solenoid through the two lap bar switches via the green wires
1) So unplug both lap bar switches and jump the wires at the plugs then jump the B & S terminals at the key switch engine should crank .
2) IF fuse does not blow then jump B & L terminals , hour meter should start counting nothing else should happen
If fuse does not blow then plug the key switch and try both positions
IF fuse does not blow one of the lap bar switches is bad or the plug has a bare wire or even spiders web shorting it so plug one in and turn key then the other till fuse blows .
IF the fuse blows at step 1 then the lap bar switches are OK & the green wire has a short some where

Click to expand...

bertsmobile1 said:

Does the new switch have the markings shown in the diagram Star posted in reply # 7
If so make 3 jumpers with a male at both ends
Unplug the engine plug to avoid accidentially putting power onto the kill wire
Now according to the same diagram this mower runs the power to trigger the starter solenoid through the two lap bar switches via the green wires
1) So unplug both lap bar switches and jump the wires at the plugs then jump the B & S terminals at the key switch engine should crank .
2) IF fuse does not blow then jump B & L terminals , hour meter should start counting nothing else should happen
If fuse does not blow then plug the key switch and try both positions
IF fuse does not blow one of the lap bar switches is bad or the plug has a bare wire or even spiders web shorting it so plug one in and turn key then the other till fuse blows .
IF the fuse blows at step 1 then the lap bar switches are OK & the green wire has a short some where

Click to expand...

Perfect. Thanks for spending the time on this. I’ll give it a try tomorrow.

The fuse is connected to the key switch and then to the solenoid and engine plug. Try unplugging the engine plug. If it still blows remove the small red wire from the solenoid. If it still blows, it sounds like a faulty key switch. If it doesn't blow with the engine plug disconnected, then from there it goes to the lights and the + side of the hour meter. Disconnect them and reconnect one at a time.

I had a fuse blowing problem with my Cub Cadet. The wire to the head light had become worn and was shorting out the system, when I turned the key to on. I'm not a mechanic, I just kept looking at the wiring.
My 2 cents.

Freddie21 said:

The fuse is connected to the key switch and then to the solenoid and engine plug. Try unplugging the engine plug. If it still blows remove the small red wire from the solenoid. If it still blows, it sounds like a faulty key switch. If it doesn't blow with the engine plug disconnected, then from there it goes to the lights and the + side of the hour meter. Disconnect them and reconnect one at a time.

Click to expand...

Freddie,
Please go back to the beginning of the thread
This is a Swisher ZTR, no lights and Star was good enough to post the wiring diagram for this mower.
HE has already tried with the engine unplugged to prove it was a machine wiring fault

bertsmobile1 said:

Does the new switch have the markings shown in the diagram Star posted in reply # 7
If so make 3 jumpers with a male at both ends
Unplug the engine plug to avoid accidentially putting power onto the kill wire
Now according to the same diagram this mower runs the power to trigger the starter solenoid through the two lap bar switches via the green wires
1) So unplug both lap bar switches and jump the wires at the plugs then jump the B & S terminals at the key switch engine should crank .
2) IF fuse does not blow then jump B & L terminals , hour meter should start counting nothing else should happen
If fuse does not blow then plug the key switch and try both positions
IF fuse does not blow one of the lap bar switches is bad or the plug has a bare wire or even spiders web shorting it so plug one in and turn key then the other till fuse blows .
IF the fuse blows at step 1 then the lap bar switches are OK & the green wire has a short some where

Click to expand...

OK. I had some time today to look at this. Here's what I did:

1. Disconnected engine plug. Turned ignition to ON. Fuse blown.
2. Jumpered lap bar switches and Ignition terminals from B to S. Engine cranks. Fuse OK.
3. Changed jumper on Ignition switch to B & L. No hour meter display. Fuse OK.
4. Removed jumper on ignition switch and plugged it in. Turned switch. Fuse OK.
5. Connected engine plug. Sat on seat to avoid any issue with kill switch. Turned ignition switch to ON. Fuse blown.
4. Disconnected hour meter. Sat on seat. Installed ignition switch jumper from B to L. Tested voltage between hour meter positive to screw on solenoid. 12 V.
5. Connected engine plug. Sat on seat. Tested voltage from hour meter positive to hour meter negative. 8 V.
6. Disconnected engine plug. Tested continuity between hour meter negative and engine plug terminal. Had continuity.
7. Followed green wire from opposite side of engine plug back to engine and disconnected. Tested continuity between engine plug terminal and the end of the wire. Had continuity.
8. Reconnnected engine plug and green wire to engine. Sat on seat. Tested voltage from hour meter positive to hour meter negative. 8 V.
9. Disconnected green wire from engine and moved it to the solenoid ground terminal. Sat on seat. Tested voltage from hour meter positive to hour meter negative. 12 V.

Also, I _think_ that I would need to have the engine plug connected for the hour meter to work. So I think that item 2) would never show anything at the hour meter. That's why I connected the engine plug and sat on the seat.

I assume that this means that the ground connection to the engine is bad. Tomorrow I'll see if I can clean the engine ground terminal and tighten the connector on the wire. When I removed the wire it seemed a little loose on the engine ground terminal.

In the diagram, with the wire (green) from the engine plug to the solenoid ground, it read 12 V at the hour meter. With the unmodified wiring (purple), it read 8 V at the hour meter.

I'm still not sure why this would cause a blown fuse...

Hopefully this is the issue, or I've provided enough information for someone to tell me what to try next.

Thank you all for your feedback. I feel a little lost here, and it's awesome that you guys took some of your time to help me out. I really appreciate it.

The set switch is a ground switch but the lap bar switches are power switches
If I read what you did correctly .
You jumped the lap bar switches at their plugs then powered the green wire by jumping B to S on the key switch plug & engine cranked that shown the green wires are fine
So you problem is in one of the lap bar switches
Plug one in leave the other jumpered then jump B to S engine cranks & fuse does not blow = good switch
Then reverse by plugging the other in and jumping the the previously plugged in one then jump B to S

Let us know what happens

That makes sense. I'll try it this weekend. I was confused when I read 8V instead of 12 V when I connected the ground to the engine. Still don't understand why it wouldn't be 12 V, but I'll try the switches.

Thanks.

chris.wyse said:

That makes sense. I'll try it this weekend. I was confused when I read 8V instead of 12 V when I connected the ground to the engine. Still don't understand why it wouldn't be 12 V, but I'll try the switches.

Thanks.

Click to expand...

I undid the jumper on one of the lap switches and plugged it in. I plugged in ignition switch and switched it to on. Fuse blew. Did the same on the other lap bar switch. Same result.

Ugh.

Did some more testing. I have two batteries connected by jumper cables. In #5 and #6, I tested from the negative terminal of the good battery which is connected to the installed battery. I'm thinking that the nominally high resistance from the solenoid ground might be due to the jumper cable connection??? On the engine ground, I couldn't even get a reading with my ohm meter.

How would I address this? I think I had a solid connection to the engine ground for testing. Should I run an additional wire from the battery negative to the engine ground lead? Is there anything else I need to consider?

​

I believe that the green wire from the hour meter runs to the oil pressure switch. When connected the voltage at the hour meter reads 8V. However when I connect to the ground on the starter solenoid, it reads 12V. Therefore, I assume that the pressure switch or its connection to ground is the issue.

Tomorrow I’ll test the pressure switch.

Does anyone concur with mu analysis??