10 hours ago
Understanding the Simon-Terex AT-60 Lift
The Simon-Terex AT-60 is a telescoping aerial lift, commonly mounted on a utility or bucket truck chassis, built for elevated work such as line maintenance, signage installation, and facility upkeep. These machines are known for their reach, stability, and versatility. However, like many older utility lifts, the wiring systems in these machines can be intricate—and after years of use, they often become a technician’s nightmare when things stop working properly.
Wiring issues are among the most common—and most frustrating—problems with older aerial lifts. Corrosion, broken connectors, worn insulation, and vague or outdated diagrams all contribute to headaches for operators and mechanics alike.
The Wiring Diagram Conundrum
One of the biggest challenges with the Simon-Terex AT-60 is locating an accurate and complete wiring diagram. Since Simon was acquired by Terex and later underwent several structural changes, documentation can be fragmented. Machines produced in the 1980s and 1990s often came with limited schematics, and replacements can be scarce.
Owners frequently rely on community knowledge, third-party service manuals, or tracing wires by hand. In many cases, original manuals were lost as these machines passed through multiple owners. As one fleet manager once quipped, “Chasing a bad wire without a diagram is like spelunking without a flashlight—you’ll probably get somewhere, but it’s gonna be painful.”
Common Electrical Issues in the Field
There are several typical wiring-related failures in AT-60 lifts:
Strategies for Repair Without a Diagram
When a wiring diagram isn’t available, technicians often resort to methodical testing and tracing:
The problem of lost technical documentation isn’t limited to Terex or lifts. Across industries, thousands of older machines—from Caterpillar dozers to Grove cranes—are still in operation with minimal factory support. That’s where crowdsourced documentation and mechanic forums have stepped in.
A similar situation occurred in 2017 when a team of rail enthusiasts rebuilt a 1950s-era Fairbanks-Morse locomotive. With no existing schematics, they reverse-engineered the control logic from physical wires and relays, eventually publishing their findings online to help others facing the same challenges.
Moving Forward: Practical Advice
If you own or work on an AT-60:
Electrical systems are the nervous systems of machines like the Simon-Terex AT-60, and just like the human body, they need clarity and connectivity to function. A missing wiring diagram can slow down repairs, but with patience, methodical work, and collaboration, even decades-old lifts can continue serving safely and reliably. In the world of heavy equipment, wiring is often invisible—until it’s all you can think about.
The Simon-Terex AT-60 is a telescoping aerial lift, commonly mounted on a utility or bucket truck chassis, built for elevated work such as line maintenance, signage installation, and facility upkeep. These machines are known for their reach, stability, and versatility. However, like many older utility lifts, the wiring systems in these machines can be intricate—and after years of use, they often become a technician’s nightmare when things stop working properly.
Wiring issues are among the most common—and most frustrating—problems with older aerial lifts. Corrosion, broken connectors, worn insulation, and vague or outdated diagrams all contribute to headaches for operators and mechanics alike.
The Wiring Diagram Conundrum
One of the biggest challenges with the Simon-Terex AT-60 is locating an accurate and complete wiring diagram. Since Simon was acquired by Terex and later underwent several structural changes, documentation can be fragmented. Machines produced in the 1980s and 1990s often came with limited schematics, and replacements can be scarce.
Owners frequently rely on community knowledge, third-party service manuals, or tracing wires by hand. In many cases, original manuals were lost as these machines passed through multiple owners. As one fleet manager once quipped, “Chasing a bad wire without a diagram is like spelunking without a flashlight—you’ll probably get somewhere, but it’s gonna be painful.”
Common Electrical Issues in the Field
There are several typical wiring-related failures in AT-60 lifts:
- Ground problems: A poor ground connection can disable joystick functions or cause erratic behavior in control systems.
- Relay failure: Old relays can burn out or fail intermittently, especially those controlling upper boom or bucket controls.
- Broken boom wiring: Wires that run through the telescoping boom often fray or break due to movement and wear. These are notoriously difficult to inspect and repair without boom disassembly.
- Ignition or PTO interlocks: If a lift will not operate, it may be due to a failed ignition interlock, neutral safety switch, or PTO engagement circuit.
Strategies for Repair Without a Diagram
When a wiring diagram isn’t available, technicians often resort to methodical testing and tracing:
- Start at the power source: Confirm 12V or 24V supply from the battery or PTO circuit.
- Use a test light and multimeter: Track voltage drops, continuity, and shorts.
- Label every wire: As wires are traced, label them with tags or shrink tubing for future repairs.
- Photograph connections: Before disconnecting anything, take clear photos for reference.
- Document findings: If you reconstruct a diagram yourself, sketch it out and share with your team—or the wider mechanic community.
The problem of lost technical documentation isn’t limited to Terex or lifts. Across industries, thousands of older machines—from Caterpillar dozers to Grove cranes—are still in operation with minimal factory support. That’s where crowdsourced documentation and mechanic forums have stepped in.
A similar situation occurred in 2017 when a team of rail enthusiasts rebuilt a 1950s-era Fairbanks-Morse locomotive. With no existing schematics, they reverse-engineered the control logic from physical wires and relays, eventually publishing their findings online to help others facing the same challenges.
Moving Forward: Practical Advice
If you own or work on an AT-60:
- Create your own wiring diagram as you repair. Even if partial, it could save hours in the future.
- Check with Terex support: While they may not provide support for Simon-era machines, they occasionally have archived manuals.
- Replace old wiring with color-coded marine-grade wire: It’s more resistant to UV, abrasion, and corrosion.
- Consider rewiring boom harnesses with modern connectors: Deutsch or Weather-Pack connectors offer much better durability than original spade or bullet terminals.
Electrical systems are the nervous systems of machines like the Simon-Terex AT-60, and just like the human body, they need clarity and connectivity to function. A missing wiring diagram can slow down repairs, but with patience, methodical work, and collaboration, even decades-old lifts can continue serving safely and reliably. In the world of heavy equipment, wiring is often invisible—until it’s all you can think about.
