This engine is on a Husqvarna YTH 1746b. Problem started after I finished mowing. It wouldn't crank so I tested the spark plug and there was no spark. Replaced it and still didn't work so I disconnected the kill wire on the ignition coil and still no spark. Replaced the ignition coil and cranked right up, however after that it was burnt out. So now I have been tearing through the electrical wiring to find anything. Voltage is hitting the kill wire when going from start-run, not run-start. No voltage coming through in either off/lights/on. Voltage is running through every ground wire I have tested when doing start-run so I can't run a new kill wire to the ignition switch. I replaced the ignition switch because it was worn out already and just hoping that could be it, but it wasn't. So now I have removed the main wiring harness so I can start tracing every wire to look for problems. FUN! Anyone else had a problem like this or have any suggestions? I disconnected the starter wiring just to make sure it wasn't the alternator or the starter when it was turning over, but it is not. It is also not the carb/alternator wiring either. It has to be somewhere in the main wiring harness/relays/plugs...at least I think so.
Yeah I'm lost right now as to what the problem is. I'm trying to think what would cause a surge in volts when the solenoid cuts power to the starter (start-run). No other electrical problems at all. I have the main wiring harness out right now and see a couple nicks in the wires but I don't think they are the problem because they aren't crossed. Gonna be a pain to get all the wires secured again.
#4
Fish
Yeah, a guy named "Rivets" is an expert in this area, he will be along shortly......
Naw, just joshing, but voltage going to the kill wire is what usually kills these coils, which is why I am very cautious when replacing coils, as the voltage that killed the old coil, will quickly kill the new one!!
No, there is no "easy" fix for what you are up against, you need to get the schematic and run it down.
Yeah I'm about to give up and take it in. I've been trying to figure this out for a few days and have gotten nowhere. Logically I can't think of why the voltage only spikes after releasing start. Why not while it is cranking?
Fish is real funny, but as usual he is out of water. Here is a schematic that may help. If you truely think that a voltage spike is causing the problem, I would pull the kill wire from the coil and hook up a separate tempory kill wire for testing. This way you can check with a meter if voltage is going through the existing kill wire. If you find voltage, I would look at the key switch plug, as it is set up with the B and M terminals next to each other. It may be shorted inside the plug. Read my signature, as you can see some imposters feel I don't know much.
The kill wire has been pulled and I was still getting a voltage spike at the other end of the plug and throughout the system. You mean hook up a temp wire to the M on the ignition switch? If so I'm getting the spike in voltage there as well too. Otherwise I would have just run a new wire and been done with it. I replaced the ignition switch because it was worn, but the plug end of it may be a good thought. I just don't understand why it's spiking when I release the key from the start position. It's really brief and not even long enough to get an accurate reading.
Just tested the brake/clutch and operator presence safety switches and they seem ok. However I tested the relay switch and I'm not getting any continuity with the middle post when it is de-energized. With 12 volts hooked up I'm getting continuity from the top and bottom posts.
"""""Yes, I stand by my reply. If you can show me how a magneto ignition system coil can get voltage out of a ground, I will change my stance. I am not going to get into a debate over this and the original poster can make is own decision how he wants to proceed, but I am done replying to your posts. Open to be friends, now you are joking, right. """"""" quote by Rivets from another thread........
Yeah, that was a quote from Rivets on another thread, just for clarity....
#11
Fish
You need to pull the keyswitch first and check the posts, on the backside they have stamped the letters indicating what they go to. If you are getting any continuance between "B" and "M' or "G", then your switch is bad. They can be real squirrelly when they start going bad, as those little springs and balls will wiggle around in the switch and short out different contacts each time.
But of course, molten or chewed up wiring is another thing to look for...
Are you saying you remove the kill wire from the coil and you still get a voltage spike on the other wire on the coil? That would be the spark plug wire? The M terminal on the key switch is used to ground the coil when you want to shut the engine down. If you pull the kill wire, M terminal, and hook a temporary kill will to the coil, you will be able to isolate the coil from the system, but still be able to shut it down when you are finished testing. I don't understand how you can get a voltage spike at the coil with the kill wire disconnected? Yes Mr. Fish, I still stand by my reply to the poster in the other thread you referenced. I believe he solved his problem by doing what I suggested, replacing the coil. This poster could have voltage spike coming from the key switch, but once the kill wire is removed there is no way for the current to get to the coil. He is asking for possible solutions and how to pinpoint the cause, not a debate. If he thinks that I have him going in the wrong direction, all he has to do is say so and I'll let you help him without getting in the way.
The keyswitch is fine. Brand new one on there and tested as well. I'm getting voltage through the kill wire that leads to the ignition coil. I'm not getting a voltage spike at the coil, just at the kill wire that is supposed to hook up to the coil. The coil isn't even on the mower right now. In fact I took the entire wiring harness out to look for problems. Today I hooked up the solenoid directly to the battery and wired it so I could engage it by touching a wire to one of the terminals. The weird thing is I'm getting 0.27 volts going from ground to ground. I bought a new solenoid just to see and it does the same thing. When I remove the the wire from ground it spikes up to 7-8 volts before going back to 0. This is with nothing but solenoid and battery. Is 0.27 volts enough to fry an ignition coil? That is constant when the solenoid is engaged and then spikes when removing one of the two ground wires. I thought for sure it had something to do with the solenoid because I only get voltage while turning over the engine and releasing the key into the run position. No other voltage readings going from off-run/lgts-run.
According to the wiring diagram, the kill wire runs from the M terminal on the key switch to the terminal on the coil. There are two non removable connections on this wire, one from terminal A on the PTO switch and the other on the clutch/brake switch. This means to me that to get a voltage spike on the coil end of the kill wire, voltage must come from one of these three terminals. M terminal on the key switch, A terminal on the PTO switch, or unmarked Black wire on the clutch/brake switch. This is assuming that there are no other shorts in the wire. Remove one terminal at a time to isolate the source.
Thanks for all the info. I'm going to repair a couple nicks in the wire and then secure the wiring harness and reinstall with the new solenoid and take a new reading with everything reattached. I don't think the nicks in the wire are the problem because they weren't crossed with anything. My question is how do I remove these terminals one at a time and still get the solenoid to engage? Everytime I've unplugged a terminal it breaks the circuit and won't allow me to do anything. I've seen a couple videos of people removing the nonremovable plugs as well. Looks like a pain but better than having to buy a new wiring harness. Also is 0.27 volts enough to fry an ignition coil?
I went and talked with a local authorized husqvarna guy and he told me it's a crapshoot and time to buy a new mower So basically start replacing stuff until I find the the problem or buy a new mower are the options he gave me.
#16
Fish
Hopefully I have guessed the correct model number, post the model number off of the tag under/behind the seat for confirmation...
I found a problem with the lights ground. With the lights on I'm getting around 225-275 mv through the ignition switch ground terminal. Also there is a black plug with a black and red wire which runs to the clutch. The black wire had been cut previously and repaired but the wire came loose when I was messing around with it. So I fixed it, but it came loose a bit again so a little copper was showing. I took a reading and got 8.9v coming through it with the blade engaged and 9.3v on the red wire. With the blade disengaged nothing.
Edit:
I have a 4 post solenoid (brand new one). I'm getting voltage when I engage the solenoid on what is supposed to be the ground terminal (2 black wires plug into it) according to the wiring diagram.
#19
Fish
So you have stopped burning up new coils then? Just leave the kill wire unplugged if you are not sure!!!!
I ended up just installing a toggle switch and running new ground wires. However, that didn't solve everything because I was still get some voltage through the dash so I put some liquid electrical tape on the switch so it wasn't touching any metal. So far that has solved the problem and no more burnt out ignition coils.
#21
Fish
Yeah, I am definitely bowing out of this one!!!! Just keep the voltage from reaching the ignition coil, and it will still run like that!!!! Do not go near that terminal!!!! Just yank the plug wire to shut down!!!!!!
So basically start replacing stuff until I find the the problem or buy a new mower are the options he gave me.