Solenoids going bad

Discussion in 'Mechanic and Repair' started by Lasko's Lawn Service, Sep 26, 2012.

  1. Restrorob

    Restrorob LawnSite Fanatic
    Posts: 11,024


    That is the voltage drop from the starter draw and it looks too low, It should be no less than 10 volts 10.5 being even better. I'd be checking into the battery closer and possibly going to a higher cranking amp battery.


    Fish...... If there's already a starter relay in the system why add a second ?

    Also..... This style solenoid does not require full 12 volts just to activate the plunger.


    With the added info above, IMO..... Battery voltage drop (from weak/bad battery) while starting (after engaging the plunger) is what's burning the plunger disc and post contacts up......
     
  2. dboyd351

    dboyd351 LawnSite Bronze Member
    Posts: 1,099

    Nice link. Thanks!
     
  3. Lasko's Lawn Service

    Lasko's Lawn Service LawnSite Member
    Posts: 183

    Yeah this relay has definitely got me interested...I'll check the battery again...thanks for the information...it definitely gives me more to play with and think about.
     
  4. JimQ

    JimQ LawnSite Bronze Member
    Posts: 1,139

    Listen to Rob. He's on the right track. I should have pulled a wiring diagram for the Tiger Cub before confusing the issue.

    He's right. There is already a starter relay in the circuit.

    I looks like Scag put suppression diodes around all of the control coils in the circuit to protect the modules (safety and fuel management on the Briggs). That's probably what your dealer was talking about. I don't believe they are causing your issue.

    Look at your battery and try a different source for a new solenoid. Purchase a quality starter solenoid. There are some real cheapies out there that don't last long.

    Q
     
  5. BigFish

    BigFish LawnSite Gold Member
    Posts: 3,064

    REDUNDANCY!!! Much like when ya drive a chevy, ya always need to carry a set of jumper cables with ya!

    Or not. No need for a relay if it already has one!!

    As was mentioned, ya need to address both positive and ground batt. cables/connections.
     
  6. Lasko's Lawn Service

    Lasko's Lawn Service LawnSite Member
    Posts: 183

    I will do a load test on that battery but its only 1 year old...worth checking...I also went to NAPA for a heavier duty car solenoid but they told me that it wouldn't work because a lawnmower solenoid is internally grounded so that it functions correctly...didn't make sense to me since there is a specific ground wire on the lawnmower solenoid...????
     
  7. JimQ

    JimQ LawnSite Bronze Member
    Posts: 1,139

    Tell them to stop thinking and give you what you just asked for.

    Generally speaking there are 2 type of solenoids most mower use.

    They all have 2 large posts for the battery in and out.

    Some have a single small post for the control coil in the solenoid. Those are internally grounded.

    1wire.jpg

    Some have 2 small posts. One post for each side of the control coil. Some manufacturers wired the safety system into the ground side of the control coil on the solenoid.

    2wire.jpg

    If you have a solenoid with the extra small post and it's not used, just create a jumper and run it to ground. I doesn't matter which post you chose.

    Q

    1wire.jpg

    2wire.jpg
     
  8. Lasko's Lawn Service

    Lasko's Lawn Service LawnSite Member
    Posts: 183

    Yeah..that's what my buddy told me to tell them too! I have the last solenoid pictured...It has two large and two small...the two small posts are the ground and the ignition wire...
    ML
     
  9. Lasko's Lawn Service

    Lasko's Lawn Service LawnSite Member
    Posts: 183

    Big Fish...the circuit does have a relay in the control panel...does this same relay act as a starter assist relay...like described above? Anyway to test that to see if its working correctly and putting the 12 volts out?
     
  10. Restrorob

    Restrorob LawnSite Fanatic
    Posts: 11,024

    If it wasn't putting out ample voltage the solenoid would not engage the plunger when the key is turned.

    As you found out from JimQ, There's no difference in auto and mower solenoids other than auto being heavier duty, Most auto parts people are nothing but computer operators.......


    Oh...... Batteries are like tires, They can be good one second and bad/flat the next......
     

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