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When a john deere riding lawn mower won’t start, the cause is often a worn starter motor, a failing starter solenoid, or a corroded relay in the starting circuit. Replacing the right part can save a trip to the dealer, but only if the part fits your deck, engine and electrical setup. This guide compares seven starter-circuit parts sold on Amazon US, organized by the problem each one solves. The selection criteria were specifications, compatibility lists, brand reputation and common owner feedback patterns. We did not install or bench-test these parts ourselves, so check fitment against your model number before ordering.
Our Top Picks
Quick Comparison
| Product | Best for | Key feature |
|---|---|---|
| Briggs and Stratton Motor Starter 593934 693551 | Owners replacing a worn starter motor on a 12HP–21HP engine | Broad engine-size fitment across several brands |
| 12V AM138068 Starter Solenoid for John Deere Riding Mower | Mowers with a clicking starter that won’t crank | Solenoid designed for the common AM138068 position |
| Starter Solenoid for John Deere AM138068 Cub Cadet 725-04439 | Owners with mixed-brand decks sharing the same solenoid | Cross-referenced to multiple tractor brands |
| LED Starter Relay Wire Harness Kit 12V 40A for John Deere | Mowers with intermittent starting or a relay that chatters | Complete relay and harness kit with LED indicator |
| Starter for John Deere Z42 LT133 LT155 LT160 LTR155 STX46 | Owners with a Kohler-powered Z-series or LT-series deck | Listed fitment for several John Deere models |
| 5777 Steel Gear Starter (14-Teeth) Replacement | Owners whose starter gear is worn or the motor spins without engaging | 14-tooth steel gear for a stronger bite on the flywheel |
| 130 160 165 170 175 180 Starter Relay w/LED Kit 12V 40A | Owners on older or mixed-brand mowers needing a relay swap | Wide list of compatible model prefixes |
Briggs and Stratton Motor Starter 593934 693551 12HP-21HP
Briggs and Stratton Motor Starter 593934 693551 12HP-21HP Fit 31C707 31R907 31P777 John Deere Z225 D105 L100 Troy Bilt Craftsman DLT-3000 Husqvarna PP19A42 YTH18542 MIA13018 SE501848 5777N
This is a good fit for owners whose engine cranks slowly, grinds, or does nothing at all, and who have confirmed the starter motor is the failing component. It is listed for a wide range of 12HP to 21HP engines, which makes it useful if you are not sure which Briggs-based engine is under your hood.
Key specs
- Engine range listed: 12HP to 21HP
- Part numbers referenced: 593934, 693551
- Listed fitment includes several John Deere, Troy-Bilt and Craftsman models
Pros
- Broad engine-size listing reduces guesswork
- Direct replacement for a worn motor, with no wiring changes
- Common part number makes cross-checking straightforward
Cons
- Fitment depends on exact engine model, so cross-check before buying
- Does not address a bad solenoid or relay, which can mimic a dead starter
12V AM138068 Starter Solenoid for John Deere Riding Mower
12V AM138068 Starter Solenoid for John Deere Riding Mower,725-04439 Solenoid Fit for LA100 LA105 LA110 LA115 LA120 LA125 D100 D105 D110 D120 D125 D130 D140 D150 D155 D160 D170
This suits owners who hear a single click when turning the key, or who see the starter engage briefly and then drop out. Those symptoms often point to the solenoid rather than the motor. The part is listed for a long series of John Deere lawn tractors, including LA and D series models.
Key specs
- Voltage: 12V
- Part number referenced: 725-04439
- Listed fitment includes LA100–LA125 and D100–D170 series
Pros
- Targets the most common click-but-no-crank failure
- Long fitment list across popular John Deere series
- Replacement is typically a few bolts and two wire terminals
Cons
- A bad battery or loose ground can produce the same click, so test voltage first
- Terminal orientation must match the original, so label wires before removing
Starter Solenoid for John Deere AM138068 Cub Cadet 725-04439
Starter Solenoid for John Deere AM138068 Cub Cadet 725-04439 MTD Troy-Bilt Trombetta 862-1211-211-16 Riding Lawn Mower Tractor
This option is aimed at owners whose mower shares a solenoid design with Cub Cadet, MTD or Troy-Bilt decks. It is a useful alternative when the John Deere-branded part is out of stock locally and the part number matches your original.
Key specs
- Part number referenced: AM138068
- Cross-referenced number: 725-04439
- Listed for riding mower and tractor applications
Pros
- Cross-reference numbers help confirm fit against an old part
- Useful for mixed-brand mowers that share a solenoid
- Straightforward swap with the same mounting footprint as the original
Cons
- Cross-brand listings can vary in terminal layout, so compare photos carefully
- Still requires confirming the failure is the solenoid and not the battery or cable
LED Starter Relay Wire Harness Kit 12V 40A for John Deere
STX30 STX38 STX46 RX63 RX75 RX95 GX70 GX75 GX95 SX75 SX95 SRX75 SRX95 F510 F525 F910 F930 AM107206 AM104506 AM102628 AM107421 LED Starter Relay Wire Harness Kit 12V 40A for John Deere
This kit is best for mowers that start only some of the time, or where the starter relay clicks rapidly. A relay that cannot hold current will cause those symptoms even when the motor and battery are healthy. The kit includes a harness, which helps when wires have become brittle or corroded.
Key specs
- Voltage: 12V
- Current rating listed: 40A
- Includes LED indicator and wire harness
Pros
- Addresses intermittent starting that single-part swaps miss
- Harness replacement reduces voltage drop from old wiring
- LED indicator helps confirm the relay is energizing
Cons
- Installation takes longer than a simple solenoid swap
- Owners report that the harness must be routed carefully to avoid chafing on the deck
Starter for John Deere Z42 LT133 LT155 LT160 LTR155 STX46
for Kohler Various Models All, Scott's S2048 for Kohler Engine 15-20HP, AM122435,5666940 SM56669 410-21041 5770N Starter for John Deere Z42 LT133 LT155 LT160 LTR155 STX46,
This starter is aimed at owners of Z-series and LT-series John Deere mowers with Kohler-type engines, where the original starter has worn out. It is a full starter assembly rather than a solenoid, so it suits a motor that has stopped turning the engine.
Key specs
- Listed fitment includes Z42, LT133, LT155, LT160, LTR155 and STX46
- Referenced numbers include AM122435 and 5666940
- Listed for Kohler engines in the 15HP–20HP range
Pros
- Complete starter assembly for a dead or dragging motor
- Covers several John Deere Z and LT models in one listing
- Reference numbers help confirm the match against your old starter
Cons
- Listing covers many engine and model combinations, so verify your exact model
- Replacing a starter involves removing the deck or engine mount on some models
5777 Steel Gear Starter (14-Teeth) Replacement
5777 Steel Gear Starter (14-Teeth) Replacement for Briggs & Stratton 593934 693551 Craftsman Lawn Mower Tractor John Deere L100 D105 Cub Cadet LT1018 14.5 17 18 18.5 19HP LG693551 33R777
This is the right choice when the starter motor spins but the engine does not turn over, which often indicates a worn or chipped pinion gear. A steel gear with 14 teeth is designed to engage the flywheel ring gear more reliably than a worn original.
Key specs
- Gear: steel, 14 teeth
- Part numbers referenced: 5777, 593934, 693551
- Listed for Briggs and Stratton engines from 14.5HP to 19HP
Pros
- Steel gear is more durable than worn original gears
- Targets a specific failure: motor spins but engine stays still
- Listed part numbers make cross-referencing practical
Cons
- Gear mismatch with the flywheel will cause grinding, so confirm tooth count
- Gear replacement may require removing the starter, which adds labor
130 160 165 170 175 180 Starter Relay w/LED Kit 12V 40A
130 160 165 170 175 180 185 240 245 260 265 285 316 318 320 325 335 345 420 F510 F525 F910 F930 RX SX STX GT LX GS AM107421 Starter Relay w/LED Kit 12V 40A Fits John Deere Kawasaki Onan
This relay kit suits owners with older or mixed-brand mowers where the starter relay has failed. Its long list of model prefixes makes it a practical option if you need to confirm compatibility by model family rather than a single part number.
Key specs
- Voltage: 12V
- Current rating listed: 40A
- Includes LED indicator kit
Pros
- Wide model-prefix list supports fitment checks
- LED indicator helps confirm the relay is energized
- Simple relay swap compared with a full harness replacement
Cons
- Long compatibility list means you must match your exact model carefully
- Does not replace a worn motor or solenoid, so it will not fix every no-start
Buying Guide
Choosing a part for a john deere riding lawn mower won’t start problem is easier when you match the part to the symptom. A single click usually points to the solenoid or battery. A spinning starter that does not turn the engine points to the pinion gear or flywheel engagement. Intermittent starting or a rapid chatter points to the relay or wiring. Start with a battery load test and a check of the ground cable before buying anything, because a weak battery can mimic every one of these failures.
Selection Criteria
- Symptom match: identify whether the failure is in the motor, solenoid, relay, gear or wiring.
- Model compatibility: check your model number, engine size and original part number.
- Voltage and current: most John Deere riding mowers use a 12V system; relays are commonly rated around 40A.
- Build quality: steel gears and complete harness kits generally outlast single-piece replacements.
Specs to Check Before You Order
- Your mower model number, usually on the data plate near the seat or under the hood
- Engine brand and horsepower, such as Briggs and Stratton, Kohler or another brand
- The original part number printed on the old starter, solenoid or relay
- Terminal count and orientation on the solenoid or relay
Choosing by Need
- Click but no crank: start with the solenoid options.
- Motor spins, engine does not turn: consider the steel gear starter.
- Dead or slow motor: look at the complete starter assemblies.
- Intermittent starting: the relay and harness kits address this more directly.
Things to Watch Out For
- Do not replace the starter until you have confirmed the battery is fully charged and the battery cables are clean and tight.
- Disconnect the battery before working on the starter circuit to prevent shorts.
- Label every wire before removal. Mixing up terminals on a solenoid can damage the electrical system.
- Cross-brand listings can look identical but differ in mounting or terminal layout.
For a broader diagnostic approach, see John Deere Lawn Mower Won't Start: 8 Causes and Fixes (2026) and Riding Lawn Mower Won't Start No Clicking: 7 Causes and Fixes. If the symptom is a clicking sound with no cranking, Riding Lawn Mower Won't Start: 7 Causes and Fixes That Work covers the battery and cable checks that should come first. Owners whose problem began after storage may also find Lawn Mower Won't Start After Winter: 7 Fixes That Work useful.
FAQ
How do I know if the starter or the solenoid is bad?
A solenoid that is failing typically produces a single click and nothing else. A starter motor that is failing often produces a slow crank, a grinding noise, or no sound at all when the key is turned. If the battery is strong and the solenoid clicks, test the solenoid by bridging the two large terminals with an insulated tool while the key is on. If the engine cranks, the solenoid is likely the problem. Consult a qualified small-engine technician if you are unsure, especially around live electrical connections.
Can a weak battery cause a john deere riding lawn mower won’t start issue?
Yes. A battery that is discharged or failing can cause a single click, dim lights, or no response at all. Charge the battery fully and clean the terminals before replacing any starter component. Many no-start complaints are resolved at this step.
Do I need to remove the engine to replace the starter?
On many riding mowers the starter is accessible from underneath or the side of the engine without removing the engine. Some models, particularly those with tight deck clearances, require removing the deck or engine mounts. Check your service manual for the exact procedure.
What is a starter relay and how does it differ from a solenoid?
The relay is a switch that carries a small control current from the key to the solenoid or starter. The solenoid is a heavy-duty switch that carries the high current to the starter motor. A failing relay often causes intermittent starting, while a failing solenoid usually causes a consistent click without cranking.
Is a steel gear starter better than the original?
Steel pinion gears are generally more durable than worn or chipped originals, but the gear must match the flywheel ring gear tooth count. A mismatch causes grinding and rapid wear. Confirm the tooth count against your original part before installing.
Should I replace the battery cables too?
If the cables are corroded, frayed or show heat damage, replace them. Corroded cables add resistance and reduce the current reaching the starter, which can mimic a failed starter motor.
When should I call a professional?
If you smell burning, see melted insulation, or are uncomfortable working with battery and starter wiring, stop and contact a qualified small-engine technician or authorized John Deere dealer. Battery work involves risk of shorts and sparks.
Conclusion
A john deere riding lawn mower won’t start problem usually traces back to the battery, solenoid, relay, starter motor or starter gear. Diagnose the symptom first, then choose the part that addresses it. For a single click with no cranking, the solenoid options are the most likely fit. For a motor that spins without turning the engine, the steel gear starter is worth considering. For a complete dead motor, the starter assemblies are the direct replacement. For intermittent starting, the relay and harness kits are the practical choice. Always confirm fitment against your model number and original part before ordering, and disconnect the battery before you begin any repair.
