Z420 Starting problem-Driving me crazy

I've got a Toro Z420 (model 74327) that I can't get to start. I mowed my yard the other day and parked it in my driveway. When I tried to start it again the motor wouldn't turn over. I could hear some clicks and buzzes coming from the starter solenoid when I turned the key. I assumed that was the problem and replaced it. No change, other than now I don't even hear any clicking or buzzing. I charged and verified that the battery was good, 12.7 volts with key on. I've got 12.7 volts to the battery side of the solenoid. It's a four post solenoid and there is no power going to any of the other posts. I checked the two system fuses that I could find and replaced the relay. Jumping 12volts to the other side of the solenoid doesn't do anything, motor still won't turn.

I'm suspecting bad ignition switch or maybe one of the many safety switches. Is there a consistent way to jump the connections on the safety switches to test them? Any help from you guys would be much appreciated.

Try this troubleshooting procedure to pinpoint the cause of your problem.



Electrical* problems can be very easy or very difficult, depending on four things.
1. * How well you understand basic electricity.
2. *What tools you have and know how to use.
3. *How well you follow directions.
4. *You don't overlook or assume anything and verify everything.

Remember we cannot see what you are doing. *You are our eyes, ears and fingers in solving this problem. *You must be as accurate as you can when you report back. *The two basic tools we will ask you to use are a test light and a multi-meter. *If you have an assistant when going through these tests it would be very helpful. *These steps work the best when done in order, so please don't jump around. *Now let's solve this problem.

First, check the fuse(s), check battery connections for corrosion (clean if necessary) and *voltage - above 12.5 volts should be good.*

Second, check for power from the battery to one of the large terminals on the solenoid. *One of the wires is connected directly to the battery and has power all the time so one of the large terminals should light a test light or show 12 volts on a meter at all times.*

Third, *check for power at the small terminal of the solenoid while depressing the clutch/brake pedal and holding the key in the start position (you may need an assistant to sit in the seat to override the safety switch). If your solenoid is a four wire solenoid, check both small wire terminals as one is ground and the other is power from the ignition switch. *If your solenoid is a three wire solenoid, make sure the solenoid body is not corroded where it bolts to the chassis of the mower as this is your ground path back to the battery. *If in doubt, remove the solenoid and clean the mounting area down to bare metal. *If there is no power to the small terminal then your problem is most likely a safety switch, ignition switch or in the wiring.*

Fourth, check for power on the other large terminal of the solenoid while holding the key in the start position (you may need an assistant to sit in the seat to override the safety switch). *If you have power what is the voltage?

Fifth, check for power at the starter while holding the key in the start position (assistant again). *If you have power what is the voltage?

Sixth, check your ground circuit back to the battery.

After you have gone through each of the above steps, let us know what happened when you did each step. *At that point we will have great info to tell you how to proceed. *Remember you are our eyes, ears, and fingers, so please be as accurate as possible.

Be as specific as possible with voltage readings as this will help diagnose your problem quicker. *If you do not know how to perform the above checks, just ask and I will try to guide you through it. *Youtube also has some videos and as you know a picture is worth a thousand words.

Bulldog80 said:

I've got a Toro Z420 (model 74327) that I can't get to start. I mowed my yard the other day and parked it in my driveway. When I tried to start it again the motor wouldn't turn over. I could hear some clicks and buzzes coming from the starter solenoid when I turned the key. I assumed that was the problem and replaced it. No change, other than now I don't even hear any clicking or buzzing. I charged and verified that the battery was good, 12.7 volts with key on. I've got 12.7 volts to the battery side of the solenoid. It's a four post solenoid and there is no power going to any of the other posts. I checked the two system fuses that I could find and replaced the relay. Jumping 12volts to the other side of the solenoid doesn't do anything, motor still won't turn.

I'm suspecting bad ignition switch or maybe one of the many safety switches. Is there a consistent way to jump the connections on the safety switches to test them? Any help from you guys would be much appreciated.

Click to expand...

Ok first your getting sound from the starter and or solenoid.
Second you jumped across the two big post on the solenoid and still no crank.
You charged and have 12 volts.

You turn the key and get sounds from the solenoid so the key switch works.

Your battery may have 12 volts but not enough amps to crank the engine.
Hook up some jumper cables from your truck battery to your mower battery and give it a try if cranks get a battery. If dies not crank then hook the same jumper cables to your truck battery and the black end to your battery - then touch the red end to the post on the starter ( don't jump back when it sparks ). If it does not turn then maybe the starter is no good.

When you jumped the two big post on the solenoid you made a straight connection to the battery. Bypassing any and all switches.

(( racing is the only sport that you need two balls ))

Carscw said:

Ok first your getting sound from the starter and or solenoid.
Second you jumped across the two big post on the solenoid and still no crank.
You charged and have 12 volts.

You turn the key and get sounds from the solenoid so the key switch works.

Your battery may have 12 volts but not enough amps to crank the engine.
Hook up some jumper cables from your truck battery to your mower battery and give it a try if cranks get a battery. If dies not crank then hook the same jumper cables to your truck battery and the black end to your battery - then touch the red end to the post on the starter ( don't jump back when it sparks ). If it does not turn then maybe the starter is no good.

When you jumped the two big post on the solenoid you made a straight connection to the battery. Bypassing any and all switches.

(( racing is the only sport that you need two balls ))

Click to expand...

Thank you for the quick reply. After changing the solenoid, now I don't get any clicking or buzzing at all. I had tried the jump start from my truck battery, nothing. I didn't get anything when I jumped power directly to the starter. This would seem to indicate a starter problem, but what would cause no power to the small solenoid terminals? Do the safety switches cut voltage from these components in this manner?

Bulldog80 said:

Thank you for the quick reply. After changing the solenoid, now I don't get any clicking or buzzing at all. I had tried the jump start from my truck battery, nothing. I didn't get anything when I jumped power directly to the starter. This would seem to indicate a starter problem, but what would cause no power to the small solenoid terminals? Do the safety switches cut voltage from these components in this manner?

Click to expand...

Yes a safety switch will cut voltage to the solenoid.
When you went right to the starter did you get a spark ?

When you put the new solenoid on did you make sure it was tight to the frame so it could be grounded?

Ok try this hook the black end of jumper cable to the engine so it makes a good ground then touch the Red to the starter post.

Are both thermals on the battery clean and tight?

Lets get it to crank then we can find out what if any switch is bad.

I do everything twice just to make sure.

(( racing is the only sport that you need two balls ))

Carscw said:

Yes a safety switch will cut voltage to the solenoid.
When you went right to the starter did you get a spark ?

When you put the new solenoid on did you make sure it was tight to the frame so it could be grounded?

Ok try this hook the black end of jumper cable to the engine so it makes a good ground then touch the Red to the starter post.

Are both thermals on the battery clean and tight?

Lets get it to crank then we can find out what if any switch is bad.

I do everything twice just to make sure.

(( racing is the only sport that you need two balls ))

Click to expand...

Yes, did get a spark, but no starter engagement which is what I was suspecting. I tried to ensure that the solenoid was grounded well and tight and I also rechecked and tightened the battery terminals when I was testing and charging it.

I will try what you suggested with grounding the jumper cables to the engine and then the positive to the starter in the morning. Even if there is some other switch issue, should this get the starter to engage?

I really appreciate the help on this.

Ok, finally got it fixed. It was the solenoid after all. When I had put on the new solenoid there was actually a smaller second wire that slipped down in the dust cover that needed to be connected to the hot side of the solenoid. As soon as I hooked it up it started. Thanks again for the help carscw