Shopping Cart: Items ($0.00)


Auto Parts
Business Operations
Concrete Saws
Lawn Mowers
Outdoor Power Equipment
Site Help
Snow Blowers


March 2014
February 2014
March 2013
November 2012
October 2012
September 2012
August 2012
July 2012
June 2012
May 2012
April 2012
March 2012
February 2012
January 2012
December 2011
November 2011
October 2011
September 2011
August 2011
July 2011
June 2011
May 2011
April 2011
November 2010
October 2010
September 2010
August 2010
July 2010
June 2010
April 2010
March 2010
February 2010
January 2010
December 2009
October 2009
September 2009
August 2009
SecurityMetrics Credit Card Safe


Lawn Mower Solenoid Testing

April 1, 2010

One of the most important parts of a lawn tractor’s electrical system is the lawn mower’s solenoid. A solenoid is a relay that energizes the engines starter motor.

Common solenoids have three (3) electrical lugs or four (4) lugs. Three lug solenoids use the mounting bracket as an electrical ground. Four lug solenoids have a dedicated ground lug.

Mower Solenoid Wiring

The common wiring method uses the large screw type lugs on top of the solenoid as follows:

The positive battery cable attaches to one of the large lugs, in addition a smaller (usually red) wire comes from the ignition switch to the same lug. This small wire carries 12 volts DC from the charging system of the engine back to the lug and in turn to the battery insuring battery re-charging.

On the other large lug a battery cable runs to the energizing lug on the starter motor. When the solenoid is energized, 12 volts DC comes from the battery to the starter.

On a 3 wire solenoid there is a small lug that energizes the main relay allowing the battery voltage to flow through the solenoid to the starter. It delivers 12 volts to the lug and energizes the solenoid allowing the starter to engage.

The previously mentioned small red wire from the solenoids battery terminal to the ignition switches battery “B” terminal has two functions. One is to carry 12 volts from the battery to the switch and conversely through the internal wiring of the switch, it carries voltage from the charging system of the engine back to the battery.

Testing Your Mower’s Solenoid

In order to check a solenoid, first you need to be sure your battery is fully charged and the solenoid is grounded. If you are not getting power to the starter motor, try this test. Take a jumper wire from the battery cable to the energizer lug on the solenoid. If the solenoid acts and the starter motor turns over then the solenoid is good.

Your no-start problem lies in the ignition switch or related wiring. If however, the solenoid doesn’t energize, then it is time to take the test one step further.

Before you replace the solenoid, again check that the solenoid is grounded. It takes just a second to run an extra ground wire from the solenoid’s metal frame (3 lug) or the ground lug (4 lug) to the negative pole of the battery. Run the test again and try to energize the starter. If it turns over, then it was a ground issue.

Time to Replace the Solenoid

If neither test energizes the starter, then replace the solenoid with the proper replacement solenoid.

Filed under: Lawn Mowers,Outdoor Power Equipment — Discount Online Parts @ 3:17 pm
Get Help or Order By Phone - 1 (877) 314-6990
Don't Miss Any SPECIALS!
Home |  Concrete Saw Parts |  Lawn Mower Parts |  Snowblower Parts |  Chainsaw Parts |  About Us |  FAQ |  Customer Service |  Privacy Policy
© 2008-2016 Discount Online Parts, LLC | All Rights Reserved
Designed by Crashbox Creative, LLC | Web design Johnson City, TN

All parts listed on this site are aftermarket parts unless otherwise noted.
All returns require a Return Merchandise Authorization (RMA) number before returning your merchandise. There will be a 15% return fee. Shipping will not be refunded if a mistake was made by the customer. There will be no returns after 30 days.