Safety-switch-related, no-starting problem?

[Alex Ethridge]

Husqvarna ZT3016.

This is an intermittent problem, sometimes starts by turning the key, sometimes behaves as though there were no battery in it at all.

The facts:

• The battery is good and has a full charge.
• Shunting the under-seat safety switch produced no effect.
• I checked checked the switch plungers for both for both right and left control arms and visibly, they appear to function as designed but I have not actually checked continuity.
• I have not checked the hand-brake safety switch yet.
• Turned on the ignition, placed all levers and controls properly for starting, then shunting the battery positive terminal to the starter will start the engine and the mower works as it should.

So where should I start looking for the problem?

 

[ILENGINE]

Need to check the switches for proper continuity. Sounds like a safety switch issue.

 

[bertsmobile1]

A dirty plunger on a safety switch will do this
A loose safety switch will do this
a wire fatigued through at the crimp will do this
A bad battery ground will do this
A bad solenoid ground will do this


When faced with one of these problems , I pull the key switch plug & jump the B & S terminals
Then it is a case of poking & proding everything till you hear the solenoid Trip

 

[Alex Ethridge]

A dirty plunger on a safety switch will do this
A loose safety switch will do this
a wire fatigued through at the crimp will do this
A bad battery ground will do this
A bad solenoid ground will do this


When faced with one of these problems , I pull the key switch plug & jump the B & S terminals
Then it is a case of poking & proding everything till you hear the solenoid Trip

Pardon my ignorance please but exactly what are the B & S terminals? I assume the S is for starter but what does the B stand for?

 

[bertsmobile1]

Battery
Some switches will have tiny letters cast into the back of the switch
B attery
S tart
G round
L ights
A lternator
Etc etc etc
The Battery terminal is usually plain red and funny enough should show battery voltage all the time .
If not then the fuse holder is suspect
I can not find any listing for a ZT 3016 so If you want more specific help please post the model product & Serial numbers from the ID tag or just post a photo of the tag .

 

[Alex Ethridge]

Battery
Some switches will have tiny letters cast into the back of the switch
B attery
S tart
G round
L ights
A lternator
Etc etc etc
The Battery terminal is usually plain red and funny enough should show battery voltage all the time .
If not then the fuse holder is suspect
I can not find any listing for a ZT 3016 so If you want more specific help please post the model product & Serial numbers from the ID tag or just post a photo of the tag .

 

[Alex Ethridge]

Sorry, I made a mistake on the model number. It is RZ3016. I've looked and looked for a service manual for it but have been unsuccessful. If you know where I can get one in PDF, please let me know.

 

[hlw49]

Could be the pto switch since the start circuit runs through it. Sometimes if you jiggle the pto switch it will work intermittently. Also look at the terminals in the terminal block and see if any of them have the center tab broken off in them.

 

[StarTech]

Husqvarna ZT3016.

This is an intermittent problem, sometimes starts by turning the key, sometimes behaves as though there were no battery in it at all.

The facts:

• The battery is good and has a full charge.
• Shunting the under-seat safety switch produced no effect.
• I checked checked the switch plungers for both for both right and left control arms and visibly, they appear to function as designed but I have not actually checked continuity.
• I have not checked the hand-brake safety switch yet.
• Turned on the ignition, placed all levers and controls properly for starting, then shunting the battery positive terminal to the starter will start the engine and the mower works as it should.

So where should I start looking for the problem?

Of course shunting (jumpering) the seat has no effect. That only effects the magneto kill circuit. Btw by doing this you are telling the mower that no one is in the seat. Also being a single pole switch the connector most likely has a shorting strip to prevent you from simply unplugging it.

Well it took a while to find a readable schematic. The following is the stupid diagram Husqvarna put in most of the zt3016 owners manuals.


But here is a readable schematic for the mower.

You have four switches in the starter circuit besides the ignition switch. Two motion control levers, brake switch, and PTO (deck switch). Note the brake has two switches.
And it looks like Husqvarna was too cheap to even put a fuse in this mower wiring harness. Just note there may be one anyway between the battery and the ignition switch.

Since voltage runs thru these switches the contacts tends to burn and become intermittent.

 

[bertsmobile1]

AFAIK there are no Husqvarna service manuals available in any form at any level for their mowers .
Wiring diagrams are usually at the start of the parts books or end of the owners instruction books .
The top one Star posted is on the last page of your owners manual and is actually the schmetic that would be used by the loom maker not a service tech.
The lower one I would like to know where Star got it from as the top one is near useless .