My ZTS7500-26HP briggs will not engage blades when PTO pulled nor do I hear a clicking noise.Tested clutch-2.6 ohmes.PTO sw has continuity. What would cause clutch to go bad?

The seat occupied switch energizes the operator presence relay. This relay allows power to the PTO clutch from the PTO switch only when energized (operator in seat).

A simple test

1.PTO switch OFF
2.Ignition switch to ON position.
3.Engine not runnjng
4.Operator in seat

Pull PTO switch. You should hear the the clutch engage with a notable pop. Then turn off PTO and it will make another pop or clunk when it disengages.

Similarly with PTO engaged, if you rise from the seat it should disengage.


Also a failed charging system may allow the engine to start and run but not provide enough current to properly engage the electric PTO clutch. With engine running check battery voltage is greater than 13VDC.

Try the following test. For safety purposes remove spark plugs. Now with engine off and key in run position turn PTO on. You should hear the clutch engage (clunk). Grab both sides of the clutch pulley and try to rotate the pulley. If the clutch is properly engaged you will not be able to rotate the clutch pulley without turning the engine.

It is most likely the the electro magnetic clutch failed.
It can be read out with an ohm meter for continuity, only 2 wires. Also verify when disconnected that it is receiving voltage from the Pto when the Pto switch is energized.

it is not supposed to start unless some one is in the seat
now for your problem, if engaging the cutter deck blows a fuse then check the wiring for a wire that is cut or shorting out on a lever that moves when the cutter is engaged

Check the safety switch on the seat.

"I have an Electric Clutch and my Blades will not engage when I operate the PTO switch."

• Turn the engine off and remove the key.
• Check for physical damage; anything look bent?
• Is the deck belt intact?
• Spin the pulley on the bottom of the clutch. Does it spin freely?
• There could be mud or grit stuck in the clutch.
• There is a drive key between the clutch and the shaft. Has this key been sheared?
• When you pull the PTO switch does the clutch make a "click"?

When you sit in the seat and turn the key, one click from off to run, you will hear a faint click. That faint click is the fuel shut off valve under the carburetor. It is turning on and off when you cycle the key from off to run. Do not confuse this click with the clutch click.

Leave the Key in the Run position, cycle your PTO Switch on and off. You will hear a click. This click will be twice as loud as the fuel switch click. This louder click is the Clutch engaging. If you do not hear this click, the PTO switch may be bad or the Clutch may be bad. This is assuming your battery is good and fully charged and that your Key Switch is functioning correctly.

PTO Clutch will Not engage or stay engaged.
There is a very fine discussion on evaluating electric clutches at this site:
http://www.messicks.com/Articles/FixingElectricClutch.aspx

My JD tech manual, which covers the entire LA 100 series, agrees with the electrical specifications. It states that the Electric PTO Clutch should show the following:

• Resistance 3.7 ohms
• Current Draw 3.25 amps.
• It does not give the air gap.

It does include a note to check the PTO Clutch Key for damage or if missing. So there is a drive key between the PTO Clutch and the shaft. Additionally, it recommends checking the tightness of the cap screw. That's the screw or bolt that holds the clutch on the shaft.

• Cap Screw torque 55 lb-ft (75 N.m).

Fixing Electric Clutches

PTO Clutch will not stay engaged.
There is a very fine one page discussion on evaluating electric clutches at this site:

http://www.messicks.com/Articles/FixingElectricClutch.aspx

My JD tech manual, which covers the entire LA 100 series, agrees with the electrical specifications. It states that the Electric PTO Clutch should show the following:

• Resistance 3.7 ohms
• Current Draw 3.25 amps.

It does not give the air gap. It does include a note to check the PTO Clutch Key for damage or if missing. So there is a drive key between the PTO Clutch and the shaft. Additionally, it recommends checking the tightness of the cap screw. That's the screw or bolt that holds the clutch on the shaft.

• Cap Screw torque 55 lb-ft (75 N.m).

Fixing Electric Clutches

Blades would not turn after I got stuck in mud. Electric clutch.

• Turn the engine off and remove the key.
• Check for physical damage; anything look bent?
• Is the deck belt intact?
• Spin the pulley on the bottom of the clutch. Does it spin freely?
• There could be mud or grit stuck in the clutch.
• There is a drive key between the clutch and the shaft. Has this key been sheared?
• When you pull the PTO switch does the clutch make a "click"? It's possible the clutch was burnt out during the mud incidence.

PTO Clutch will not engage or stay engaged.
There is a very fine discussion on evaluating electric clutches at this site:
http://www.messicks.com/Articles/FixingElectricClutch.aspx

My JD tech manual, which covers the entire LA 100 series, agrees with the electrical specifications. It states that the Electric PTO Clutch should show the following:

• Resistance 3.7 ohms
• Current Draw 3.25 amps.
• It does not give the air gap.

It does include a note to check the PTO Clutch Key for damage or if missing. So there is a drive key between the PTO Clutch and the shaft. Additionally, it recommends checking the tightness of the cap screw. That's the screw or bolt that holds the clutch on the shaft.

• Cap Screw torque 55 lb-ft (75 N.m).

Fixing Electric Clutches

Blades would not turn after I got stuck in mud. Electric clutch.

• Turn the engine off and remove the key.
• Check for physical damage; anything look bent?
• Is the deck belt intact?
• Spin the pulley on the bottom of the clutch. Does it spin freely?
• There could be mud or grit stuck in the clutch.
• There is a drive key between the clutch and the shaft. Has this key been sheared?
• When you pull the PTO switch does the clutch make a "click"? It's possible the clutch was burnt out during the mud incidence.

PTO Clutch will not engage or stay engaged.
There is a very fine discussion on evaluating electric clutches at this site:
http://www.messicks.com/Articles/FixingElectricClutch.aspx

My JD tech manual, which covers the entire LA 100 series, agrees with the electrical specifications. It states that the Electric PTO Clutch should show the following:

• Resistance 3.7 ohms
• Current Draw 3.25 amps.
• It does not give the air gap.

It does include a note to check the PTO Clutch Key for damage or if missing. So there is a drive key between the PTO Clutch and the shaft. Additionally, it recommends checking the tightness of the cap screw. That's the screw or bolt that holds the clutch on the shaft.

• Cap Screw torque 55 lb-ft (75 N.m).

Fixing Electric Clutches

Depending on your engine.. Briggs and Stratton or Kohler there are 2 different seat switches that are used to power the PTO clutch. The seat switch can cause the PTO clutch to disengage anytime there is not at least 70 lbs in the seat.

The PTO drive wiring has a 30 amp fuse in it. If by chance a stick went through the belt and tore off the wires at the PTO clutch (Common failure) even after you repair the broken wire you still need to replace the fuse.

Check the PTO clearance gap. It should be 0.012 dis-engaged. Any other value and the clutch will not work correctly. Adjust the clutch if necessary.

There is a 2 pin Pigtail just off of the PTO Clutch that you need to check for voltage at the connector. Probe the back of the wires if you can and your looking for 12V DC under the following conditions.

BRAKE ON or tied down
KEY ON
SEAT (Briggs and Stratton engine only) Someone needs to be sitting on the seat.

Then Pull the PTO Switch out. You should hear the PTO Clutch CLICK. If you hear the click there is no need to check voltage. The PTO switch is a multi function switch and it is quite possible the PTO switch failed. I doubt that the PTO Clutch has failed as they normally give you some kind of noisy indication that they are failing and don't fail straight away.

So.. In short
Check PTO Switch (Red wires) to usually red or brown thru the switch
Check 30 amp fuse
Check PTO clutch wires near PTO clutch (They get torn from something traveling through the pulley)
Check PTO clutch clearance at 0.012
Check Brake switch for an audible click as you depress it some distance No click.. possible bad switch
Listen for Seat switch Click as you slowly add weight to the seat. No Click or any click and it can still be suspect due to the Briggs and Stratton installed engine ones have more than one function.. Ignition and PTO clutch power.

The actual wiring diagram is on page 35 of the owners manal that can be found here:
http://www.managemylife.com/mmh/owner_manuals/27245/CRAFTSMAN-Lawn,-Tractor-L9910386?brand_name_search=917273023

Lastly... check each of the mower deck blade bearings. A seized bearing can cause PTO problems.

Hopefully you have enough information to solve the mystery. If not just respond here and I will help you.

Thanks for choosing FixYa.

Kelly