JLG SkyTrak 10054: Locating the Flasher Relay and Diagnosing Turn Signal Failures

[MikePhua]

Introduction
The JLG SkyTrak 10054 telehandler is a high-reach material handler widely used in construction and industrial settings. Like many machines in its class, it relies on a combination of mechanical and electrical systems to manage safety features such as turn signals and hazard flashers. When these systems fail—especially when power is present at the switch but no flashing occurs—the culprit is often a hidden or misidentified flasher relay. This article explores the technical aspects of flasher relay location, clarifies relevant terminology, and shares field-tested insights to help operators and technicians resolve signal failures.
Understanding the Flasher System
The flasher system in the SkyTrak 10054 includes several key components:

• Turn signal switch
  
• Hazard switch
  
• Flasher relay
  
• Fuse compartment
  
• Indicator lamps
  
• Wiring harnesses and connectors
  

These components work together to create the rhythmic on-off signal required for turn and hazard indicators.
Terminology Clarified

• Flasher Relay: An electromechanical or solid-state device that interrupts current flow at regular intervals to create a flashing effect.
  
• Fuse Compartment: A panel housing fuses and relays, typically located under the dashboard or near the operator’s seat.
  
• Wiring Diagram: A schematic showing electrical connections and component locations.
  
• Part Locator Diagram: A visual guide to physical component placement, often separate from wiring schematics.
  

Symptoms and Initial Observations
Operators have reported:

• No function from turn signals or hazard lights
  
• Power confirmed at the switch terminals
  
• Flasher relay listed in wiring diagram but not shown in part locator diagram
  
• No visible relay in the fuse compartment
  

These symptoms suggest that the flasher relay may be mounted remotely or embedded within a harness or accessory panel not covered by standard diagrams.
Field Anecdote: Montreal Mechanic’s Search
A technician in Montreal encountered a non-functioning flasher system on a SkyTrak 10054. Despite verifying power at the switch and consulting the manual, he could not locate the flasher relay in the fuse compartment. The wiring diagram referenced a relay part number, but the physical location remained elusive. This led to speculation that the relay might be tucked behind the dashboard, near the steering column, or integrated into a secondary harness.
Historical Insight: Relay Placement in Telehandlers
In many telehandlers from the early 2000s, flasher relays were mounted behind instrument panels or within auxiliary fuse blocks. Manufacturers often placed them near the steering column or under the operator’s console to reduce wiring length. However, these locations were not always documented in part locator diagrams, leading to confusion during troubleshooting.
Similar issues were reported in older Genie and Gradall models, where flasher relays were zip-tied to harness bundles behind the dashboard. Technicians learned to trace the hazard switch wires manually to locate the relay.
Case Study: Relay Replacement and System Restoration
A field mechanic in Texas restored flasher function on a SkyTrak 10054 by removing the lower dashboard panel and tracing the hazard switch wires. He found the relay mounted on a bracket behind the steering column, partially obscured by the wiring harness. After replacing the relay with a compatible unit, both turn signals and hazard lights resumed normal operation.
Best Practices for Locating and Replacing Flasher Relays

• Use the wiring diagram to trace power and ground paths from the switch
  
• Inspect behind dashboard panels and under the operator’s console
  
• Look for relay-shaped components zip-tied to harnesses or brackets
  
• Verify relay function by testing continuity and resistance
  
• Replace with OEM or equivalent flasher relay rated for 12V systems
  

Anecdote: The Invisible Relay and the Veteran Tech
A veteran technician in Alberta recalled spending hours searching for a flasher relay on a SkyTrak 10054. After removing multiple panels and consulting outdated manuals, he finally found the relay mounted inside a small junction box behind the seat. The experience taught him to trust the wiring diagram more than the part locator—and to always carry a flashlight and patience.
Conclusion
Flasher relay failures in the JLG SkyTrak 10054 can be deceptively difficult to diagnose due to undocumented mounting locations and inconsistent diagrams. By understanding the system architecture and tracing wiring paths, technicians can locate hidden relays and restore signal functionality. In machines where visibility and safety are paramount, even a small relay plays a big role—and finding it is often a test of persistence and experience.