Need some help with Cub Cadet RZT mower

Discussion in 'Mechanic and Repair' started by weicm3, Nov 7, 2009.

  1. weicm3

    weicm3 LawnSite Member
    Posts: 19

    Hi,

    The mower has been working fine thru the summer but about 1 month back, I couldn't get it started due to low voltage(was showing 9.x on the mower's voltage meter). So, I put the booster battery on and I could jump started it at that time. A few days after I tried to start it and it worked fine. But today I tried to use it, it wouldn't start again. I slow charged the battery to 12.5V but when I turn the key to on, the voltage meter shows 9.5-10.0 immediately. It didn't even click when I turned the key to start position.

    When I turned switch off and measured voltage at terminals, it still showed 12V. But once I switch it on, the voltage dropped. I cleaned all the ground points I could find but was still the same. And I couldn't even jump start it. The voltage meter on the booster would drop to the same reading showing on mower's voltage meter.

    Does that mean the battery is dead? If so, why it still shows 12V at terminals after I turn the key off? And if it's battery, I should still be able to jump start it, right? Or do I have a bad solenoid? How do I further troubleshooting it?

    Thanks in advance!
     
  2. Restrorob

    Restrorob LawnSite Fanatic
    Posts: 11,024

    Battery has a blown strap or is shorted, In either case they will show voltage until a load is applied.

    Replace the battery then check the charging system.....
     
  3. weicm3

    weicm3 LawnSite Member
    Posts: 19

    But if it's battery issue, why jump start didn't work this time? The voltage meter on my booster battery showed the same reading(9.x V) after I switch the key to on position. I kind of suspecting starter solenoid but don't know how to test them to isolate the problem.
     
  4. Restrorob

    Restrorob LawnSite Fanatic
    Posts: 11,024

    OK, What's the voltage drop with the key in the start position ?
     
  5. weicm3

    weicm3 LawnSite Member
    Posts: 19

    here are the readings.

    key off: 12.4V (measure thru multimeter at battery posts)
    key in on/run position: 10V (voltage meter on mower. measured with multimeter at posts and it's the same 10V.)
    key in start position: 9.5V (voltage meter on mower)

    one thing I found might or might not be related is that if I sit in the seat (there is a seat safety rely in this mower), I could see the voltage reading went from 10V to 10.1V.
     
  6. Restrorob

    Restrorob LawnSite Fanatic
    Posts: 11,024

    Post the full model number off the white label.


    Sound like you have more than one problem, It shouldn't be dropping almost 2.5 volts just turning the key on. It shouldn't drop more than 9.5 in the start position while the starter is spinning putting a load on the battery, Which it isn't from what you explain.


    So, If the solenoid isn't clicking when you turn the key to start position I would suggest checking the parking brake safety switch first, Once the non clicking solenoid is solved the rest can be checked.
     
  7. weicm3

    weicm3 LawnSite Member
    Posts: 19

    I don't have the model number right now. It's out in the shed and it's cold and dark now. I have been reading this service manual online (http://www.mymowerparts.com/pdf/Cub...ZT_Series_Zero_Turn_Service_Repair_Manual.pdf) This is the exact mower I have and wiring diagram is in this document.

    The parking brake safety seems fine because I can see the red light on the console when parking brake is engaged. (and goes away when it's released)

    The voltage drop from on to start position was about 0.5V (10V->9.5V)

    What could be the reason that causes voltage drops when turning the key to on position?
     
  8. Restrorob

    Restrorob LawnSite Fanatic
    Posts: 11,024

    The brake switch has double contacts inside, Just because you have a idiot light showing doesn't mean the switch is working properly. You have to start someplace and that's where I suggested, The switch can be tested with a multimeter set on ohm's scale. You also have the brake switch relay, Try swapping it with the pto relay and see if you can get the starter to click.


    From past experience I just have to ask; You do have the pto switch turned off correct ?
     
  9. weicm3

    weicm3 LawnSite Member
    Posts: 19

    yes. the pto switch is off when I tried to start the mower and it seems functioning properly as I can hear the click sound when I switch it on and off.

    I'll spend sometime today to try the brake switch.
     
  10. weicm3

    weicm3 LawnSite Member
    Posts: 19

    I didn't have time to play around with the relay yesterday. But found something weird. When I first turned the key to on position to get the voltage reading and it surprisingly showed 12V and the battery warning light was no longer lit.

    So, I thought it would start up. Jumped on the seat and ready for a start. But as soon as I turned the key to start position, no click, no sound, nothing and voltage meter showed reading at 9.5V again. :confused:

    Then I let it rest for a couple minutes by turning the key to off position. When I turned it to on position again, it showed only 10V. Does it mean my switch(key) or solenoid is going south? Seems something was drawing voltage once key is turned to start position.

    edit: I did try to put my finger on the brake relay and could feel a click when the parking brake was engaged.
     

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