Pothole Guard Fault, Deploy Failure Detected

Common Symptoms

• Platform LCD on the upper control box displays code 13
• Machine will not travel at high speed, only slow creep is available or drive is fully blocked
• Pothole protection bar appears to be up or partially deployed but the machine still faults
• Drive function cuts out as soon as you leave the stowed position
• No audible click or mechanical movement when pothole guard should drop
• Fault clears momentarily then returns when you attempt to drive
• Platform is elevated but high-speed drive remains locked out

Probable Causes (Ranked by Likelihood)

• Pothole guard limit switch failed, corroded, or out of adjustment so it never confirms the deployed position Very Likely
• Pothole guard bar physically stuck up due to debris, bent linkage, or seized pivot pin and not dropping when platform rises Very Likely
• Wiring harness to the pothole guard limit switch is broken, chafed, or has a loose connector Likely
• Pothole guard solenoid or actuator has failed and is not releasing the bar Likely
• Guardian or RDC2 controller not receiving a valid closed signal from the limit switch circuit Possible
• Platform height sensor disagrees with pothole guard state, causing a logic mismatch in the controller Possible
• Damaged or corroded ground connection at the pothole guard switch mounting point Less Likely

Step-by-Step Diagnostic Procedure

1. Start on the ground with the platform fully lowered. Visually inspect the pothole guard bar on all four corners. Each bar should be resting down against the floor or pavement when the machine is stowed. If any bar is hanging up, look for bent linkage, a jammed pivot, or debris blocking the drop path.

2. Raise the platform 2 to 3 feet. The pothole guard bars should drop down automatically as height increases. Watch each bar as the platform rises. If a bar stays up, you found your mechanical fault. Free the linkage, clear debris, and lubricate the pivot pins with a light penetrating oil.

3. With the platform raised and bars in the deployed position, locate the pothole guard limit switch. On most SJIII series machines there is one switch per side mounted to the chassis near the guard pivot. With a multimeter set to DC continuity or voltage, check that the switch is closing when the bar is fully down. A healthy closed switch should show continuity or a signal change at the controller input terminal.

4. Check the wiring from the limit switch back to the main harness connector. Look for chafed insulation, pinched wires at the chassis fold points, and corroded terminals. Wiggle the harness while watching the Platform LCD on the upper control box. If the fault clears and returns when you wiggle, you have an intermittent wire or connector.

5. At the limit switch connector, measure DC voltage between the signal wire and chassis ground with the platform raised and bars deployed. Compare your reading to the Skyjack wiring diagram for your model. Typical input circuits read battery voltage when open and near 0 V when closed, or vice versa depending on switch type. A reading that never changes regardless of bar position means a bad switch or broken wire.

6. If the switch and wiring check out, inspect the pothole guard solenoid or release actuator if your model uses one. Apply direct battery voltage to the solenoid terminals and confirm it energizes and releases the bar. No movement with direct power means a failed solenoid.

7. If mechanical and electrical components test good and code 13 persists, connect the Skyjack diagnostic harness via the EZcal or Pcal handheld. Review the input status screen for the pothole guard switch input and confirm the controller sees the state change. A controller that does not see the input change with a confirmed good switch points to a failed Guardian or RDC2 input channel.

8. After any repair, lower the platform fully, cycle the key, raise the platform again, and confirm code 13 is gone and high-speed drive is restored before returning the machine to service.

Frequently Asked Questions