March 1, 2017

How to replace the brake interlock switch on a riding lawn mower

By Lyle Weischwill
How to replace the brake interlock switch on a riding lawn mower

This DIY riding mower repair guide gives step-by-step instructions for replacing the brake interlock switch on a riding lawn mower. When working correctly, this safety switch keeps the engine from starting if your foot isn’t pressing down on the brake or if the parking brake isn’t set. If the switch breaks, it won’t let current reach the starter solenoid coil even though the brake is on, and the engine won’t start. If the solenoid doesn't click when you turn the ignition key, the brake interlock switch is most likely at fault. Watch this lawn tractor troubleshooting video to learn how to test the starting system and brake interlock switch. Replace the brake interlock switch with a manufacturer-approved replacement part.

You can use the steps in this guide to replace a broken brake interlock switch on common Craftsman, MTD, Troybilt, Husqvarna, Cub Cadet, Snapper and Ariens lawn tractors and riding mowers.

Quick links
Tools required
Wrench set
Work gloves
Repair difficulty
Time required
30 minutes or less
Repair difficulty
Time required
30 minutes or less
Replacing a brake interlock switch on a riding lawn mower

Replacing a brake interlock switch on a riding lawn mower.

Instructions

  1. 01.

    Disconnect the battery

    Park the tractor on a level surface, but don't set the parking brake so that you'll be able to remove the brake interlock switch.

    Turn the ignition switch off and remove the key.

    Wear work gloves to protect your hands.

    Lift the seat.

    Remove the bolt connecting the negative cable to the battery and tuck the cable away from the battery so it doesn't touch the battery post.

    Disconnect the battery.

    Disconnect the battery.

  2. 02.

    Release the steering plate

    Lower the mower deck to its lowest position.

    Remove the left rear steering plate mounting bolt.

    Remove the left front steering plate mounting bolt and the upstop bracket.

    Remove the upstop bracket.

    Remove the upstop bracket.

  3. 03.

    Remove the brake interlock switch

    Lift the hood.

    Remove the lower dash fastener and pull off the lower dash.

    Remove the wire harness from the brake interlock switch.

    Squeeze the brake interlock switch mounting tabs and push the switch down to release the switch from the tractor frame.

    Push straight down on the brake pedal to lower the steering plate and remove the brake interlock switch.

    Tip: Remove the fuel tank and rest it on top of the engine if you need more room.
    Remove the brake interlock switch.

    Remove the brake interlock switch.

  4. 04.

    Install the new brake interlock switch

    Position the new brake interlock switch under the tractor frame.

    Push straight down on the brake pedal to lower the steering plate and snap the new brake interlock switch onto the tractor frame.

    Connect the wire harness to the new brake interlock switch.

    Reinstall the lower dash and secure it with the fastener.

    Lower the hood.

    Connect the brake interlock switch wire.

    Connect the brake interlock switch wire.

  5. 05.

    Reinstall the steering plate

    Position the upstop bracket on the frame and reinstall the left front mounting bolt in the steering plate.

    Reinstall the left rear mounting bolt in the steering plate.

    Reinstall the upstop bracket.

    Reinstall the upstop bracket.

  6. 06.

    Reconnect the battery

    Set the parking brake.

    Reconnect the negative cable to the negative battery terminal.

    Lower the seat.

Warning: Undertaking repairs or maintenance to appliances or power equipment can be hazardous. Should you choose to undertake repairs or maintenance, you are assuming the risk of injury to your person or property. In an effort to reduce the risk, use the proper tools and safety equipment noted in the applicable guide and follow all instructions. Do not proceed until you are confident that you understand all of the steps and are capable of completing the repair. Some repairs or maintenance, however, should only be performed by a qualified technician.

Symptoms common to all riding mowers & tractors

Choose a symptom to see related riding mower and lawn tractor repairs.

Main causes: dead battery, stale fuel, bad starter solenoid, ignition system problem, bad ignition interlock switch, clogged carburetor
Main causes: damaged cutting blade, worn deck pulley, damaged mandrel pulley, loose fasteners on mower deck components
Main causes: shift lever needs adjustment, neutral control needs adjustment
Main causes: engine overfilled with oil, leaky head gasket or sump gasket, damaged carburetor seals, cracked fuel pump, broken fuel line
Main causes: punctured tire or inner tube, leaky valve stem, damaged wheel rim
Main causes: worn or broken ground drive belt, bad seat switch, transaxle freewheel control engaged, transaxle failure, dirty carburetor
Main causes: unlevel mower deck, dull or damaged cutting blades, worn mandrel pulleys, bent mower deck, engine needs tune up
Main causes: worn or broken blade belt, broken belt idler pulley, blade clutch cable failure, bad PTO switch, damaged mandrel pulleys
Main causes: clogged carburetor, damaged flywheel key, dirty spark plug, stale fuel, improper valve lash, engine needs a tune up

Repair guides common to all riding mowers & tractors

These step-by-step repair guides will help you safely fix what’s broken on your riding mower or lawn tractor.

How to replace the air filter on a riding lawn mower

Get your mower running smoothly again by replacing the air filter—it's a quick job you can do yourself, following these steps.

Repair difficulty
Time required
 15 minutes or less
How to replace the starter motor on a riding lawn mower

If you hear the solenoid click but don’t hear the starter motor spin when you turn the key, follow these steps to replace it.

Repair difficulty
Time required
 30 minutes or less
January 1, 2015
By Lyle Weischwill
How to replace a riding lawn mower blade

If a blade on your mower is dull or bent, replace it following the steps in this repair guide.

Repair difficulty
Time required
 30 minutes or less

Articles and videos common to all riding mowers & tractors

Use the advice and tips in these articles and videos to get the most out of your riding mower or lawn tractor.

May 1, 2017

Riding lawn mower engine spins but won't start video

By Sears PartsDirect staff

Troubleshoot fuel, spark and compression issues.

May 1, 2017

How to repair a riding lawn mower tire video

By Sears PartsDirect staff

Learn when you can use sealant to fix a flat tire.

June 1, 2016

How to mow a lawn for healthier grass

By Erin Hynes

How often and tall you mow your lawn has a big impact on its health. Check out these 3 rules.