Bobcat S510 Starter Switch Wiring Problems

[MikePhua]

Background on the Bobcat S510 and Its Electrical System
The Bobcat S510 is a mid-frame skid steer loader launched in the early 2010s as part of Bobcat’s M-series compact equipment family. It typically comes with a rated operating capacity around 1,850–1,900 lb, and thousands of units have been sold worldwide as a popular choice for construction, agriculture, rental fleets, and landscaping work.
Like most modern skid steers, the S510 uses a 12-volt electrical system with multiple safety interlocks, control modules, and a multi-position ignition or starter switch. This switch is more than a simple “on/off” key; it has several positions, often including:

• Off
  
• Auxiliary / accessories
  
• Run / preheat
  
• Start
  

This small component is a critical node in the machine’s wiring harness. Mis-wiring it can lead to no-start conditions, intermittent faults, blown fuses, or even damage to control modules. Yet in the real world, it is common for machines to arrive at a shop with “mystery wiring” after someone pulled wires off the back of the switch, either while troubleshooting or swapping parts without documentation.
The Scenario Wires Pulled Off a Four-Position Starter Switch
In the specific case discussed, a Bobcat S510 built around model year 2013, with product identification number (PIN) A3NJ11106, arrived with its four-position starter switch disconnected. Someone had pulled multiple wires off the rear of the ignition switch, leaving only a few loose wires and the switch terminals. Without a wiring diagram or a labeled harness, reconnecting these wires correctly is not obvious.
This problem is more common than many owners admit. A rough estimate from small independent shops suggests that around 10–20% of used compact equipment they see has had some kind of “creative” wiring modification near the key switch, safety interlocks, or starter relay. When the machine changes hands or comes in for service, the new technician is left to guess what the last person did.
In this case, the owner initially turned to other operators and technicians looking for:

• A wiring diagram
  
• A service or repair manual
  
• Clear pictures of the back of the switch with wires in the correct locations
  

But rather than wait and hope someone had the exact same model and configuration, the owner chose another path: acquire the official information from the manufacturer’s documentation and solve the problem directly.
The Role of Service Manuals and Wiring Diagrams
A service manual is the factory-level technical document that includes:

• Electrical system descriptions
  
• Complete wiring diagrams
  
• Connector pinouts
  
• Component locations
  
• Diagnostic procedures and test values
  

For a modern skid steer, the ignition system usually includes:

• Key or starter switch with labeled terminals (e.g., BATT, ACC, RUN, START)
  
• Power feed from the battery or fuse panel
  
• Circuits feeding control modules, instrument cluster, and safety systems
  
• Start signal going to a starter relay or solenoid
  

On paper, wiring diagrams look intimidating, but once you understand the symbols, they become a map that shows which wire should land on which terminal. Rather than trial-and-error “let’s see what smokes,” a wiring diagram turns the job into a clean, logical process.
In the S510 case, the owner realized that purchasing the correct manual was very inexpensive compared to the risk of damage or downtime. After obtaining the manual, they used the official wiring diagram to:

• Identify each wire color and its circuit function
  
• Match each wire to the correct position on the four-position switch
  
• Verify that the terminal markings on the switch matched the diagram
  
• Reattach the wires properly and test operation
  

The outcome was clean and satisfying the machine started and ran well after proper wiring was restored.
Typical Wiring Layout for a Four-Position Starter Switch
Although exact colors and codes vary by manufacturer and year, a four-position switch on a skid steer often follows this general logic:

• One heavy gauge wire bringing fused battery power to the switch (BATT or 30)
  
• One or more outputs for accessories and control power (ACC or IGN)
  
• A dedicated output to energize the preheat or run circuit
  
• A spring-return “START” terminal that sends power to a starter relay or solenoid
  

Rewiring without a diagram is dangerous because:

• Swapping ACC and IGN feeds can power the wrong circuits at the wrong time
  
• Feeding power directly to the start circuit without proper interlocks can bypass safety switches
  
• Mis-routing power into a data line or control module can damage expensive electronics
  

A service manual keeps you away from these traps.
Why Guesswork Is Risky on Modern Skid Steers
Older machines with simple mechanical key switches and few electronics sometimes tolerated a bit of improvisation. But on a modern loader like the S510, you are dealing with:

• Electronic control modules
  
• CAN bus communication on some configurations
  
• Complex safety circuits for seat bar, seat switch, and auxiliary hydraulics
  
• Engine protection features for oil pressure, coolant temperature, and so on
  

Incorrect wiring at the starter switch can trigger:

• No-start conditions
  
• Random warning lights
  
• Failure of safety functions
  
• Hard-to-trace intermittent faults
  

In a survey of small equipment repair shops, many report that electrical problems caused by “home-made” wiring repairs are among their most time-consuming jobs often exceeding several hours of labor per machine to untangle. A correct diagram frequently cuts diagnostic time by more than half.
Practical Steps for Reconnecting a Pulled-Off Switch
When facing a situation where someone has pulled wires off an ignition or starter switch on a machine similar to the S510, a systematic approach can prevent frustration:

• Identify the machine precisely
  • Record model, serial/PIN, and model year.
    
  • Note any optional equipment that may affect wiring (AC, deluxe instrumentation, etc.).
    
• Obtain proper documentation
  • Purchase or access the factory service manual or at least the electrical section.
    
  • Avoid relying solely on partial online diagrams or “similar model” layouts.
    
• Label and inspect the harness
  • Examine each wire for printed circuit codes and colors.
    
  • Check the harness for previous splices, burnt insulation, or non-original connectors.
    
• Match terminals and circuits
  • Identify the switch terminals by the markings on the plastic or metal body.
    
  • Using the diagram, match each wire to its appropriate terminal by function, not just by guessing color.
    
• Test step by step
  • Before fully reassembling, test each key position with a multimeter.
    
  • Confirm that “OFF” truly cuts power, “RUN” feeds the correct systems, and “START” energizes the starter relay only when turned fully.
    
• Secure and protect
  • Use proper connectors or terminals as specified in the manual.
    
  • Ensure strain relief so wires are not easily pulled off again.
    

A Short Story from the Shop Floor
Many technicians can tell a story similar to this S510 case. For example, in one small workshop, a skid steer arrived with the owner saying “it just stopped cranking” after a friend tried to “fix the key switch.” When the tech pulled the panel, they found:

• Three wires twisted together and taped
  
• One large battery feed wire dangling loose
  
• The start terminal shorted directly to a small control wire
  

The machine had several blown fuses, and one control module had started to overheat. After ordering the proper manual and studying the diagram, the tech re-wired the switch correctly in under an hour. The machine then started perfectly and, more importantly, ran without any random faults. The owner admitted that if they had bought the manual first, they would have saved both time and a damaged module.
The History and Scale of Bobcat and the S-Series
Bobcat, originally founded in the late 1950s, became famous for inventing the compact skid steer loader concept. Over the decades, Bobcat has sold well over half a million skid steers globally, and the S-series (including models like S185, S650, and S510) has been a major contributor to those numbers.
The S510 sits in the middle of the range, designed for contractors who need a balance between lift capacity, maneuverability, and transport weight. Its popularity means:

• A large population of machines still working on job sites and farms
  
• High demand for service information and parts
  
• A steady flow of machines into the used market and independent shops
  

Because there are so many S-series machines in circulation, keeping their electrical systems correct and safe is critical. A single wiring mistake can sideline a machine that might otherwise work reliably for thousands more hours.
Lessons Learned and Recommendations
From the simple S510 case where “somebody pulled wires off at the starter switch,” several broader lessons emerge:

• Buy the manual early
  The cost of an official service manual is usually trivial compared to a day of lost downtime or a fried control module.
  
• Do not rely on memory or guessing
  Even if you have “only four wires and four terminals,” one wrong connection can bypass safety interlocks or damage electronics.
  
• Document your work
  When you repair or modify wiring, note what you did. Future technicians including your future self will thank you.
  
• Respect the starter switch as a safety component
  It is not just a key that turns the engine; it controls power to safety circuits and essential systems.
  
• Encourage best practices in the used market
  When buying or selling used skid steers, ask about manuals, wiring integrity, and whether any harness modifications have been done. Machines with untouched, correctly documented wiring generally hold value better and have fewer hidden problems.
  

Conclusion The Value of Proper Information
In the end, the solution for the mis-wired Bobcat S510 was straightforward: obtain the correct wiring diagram, reconnect the starter switch according to factory specifications, and verify that the machine operated as intended. Once that was done, the loader was back to work, with no lingering mystery about what each wire did.
This small story is a reminder that modern compact equipment lives and dies by its documentation. When wires are pulled, labels are lost, and memories fade, the service manual becomes your most reliable tool. Instead of fighting the machine or chasing ghosts in the harness, you can follow clear diagrams, restore the system to its designed state, and send the machine back into the field with confidence.