Arrow boards and portable message boards spend their lives in some of the worst environments we put equipment into: highway shoulders exposed to direct sun, rain, road debris, and the constant vibration of high-speed traffic passing a few feet away. They're also, in most fleets, the last piece of equipment to get scheduled preventive maintenance attention. The result is predictable failure modes — almost all of which are preventable — that show up at inconvenient times and take the board out of service during an active work zone.
LED Cluster Failure
LED technology has dramatically improved arrow board reliability compared to the incandescent systems that preceded it, but LED clusters still fail — and they fail in patterns that carry diagnostic information.
Single-cluster drop-out is the most common presentation. One square in the arrow board goes dark while the rest illuminate normally. The usual cause is a failed LED module or a corroded connector at that module's harness junction. On most boards, including current Wanco and Ver-Mac units, individual LED modules are designed to be field-replaceable — though the procedure varies by model and should be performed per the manufacturer's service documentation rather than improvised. The bigger diagnostic question is why that cluster failed: if it's corrosion at the connector, the adjacent connectors are likely developing the same condition.
Row or column dropout suggests a failed driver board or a break in the wiring harness that feeds a segment of the panel. This typically requires bench diagnosis rather than a quick field swap.
Gradual dimming across the panel points to power supply issues — either the battery bank is undercharged, the solar charge controller is degraded, or there's voltage drop in the main feed wiring due to connection corrosion or a corroded positive bus terminal.
Preventive practice: inspect LED cluster connectors annually. Apply dielectric grease to connector faces during each inspection. Any connector showing discoloration, pitting, or resistance to seating should be replaced, not cleaned and reinstalled.
Solar Charge Controller Failures
Most trailer-mounted arrow boards and message boards use solar panels as their primary charge source, with a battery bank providing overnight and cloudy-day storage capacity. The charge controller sits between the panel and the batteries and manages charge rate, voltage regulation, and battery protection. When it fails, the batteries run flat — sometimes gradually, sometimes overnight.
Charge controller failures fall into a few categories:
- Thermal failure: Controllers mounted in enclosures that don't shed heat adequately can overheat in summer conditions. North Texas summer heat accelerates this significantly. Controllers have model-specific temperature ratings — confirm your unit's rated ambient temperature, as internal enclosure temperatures in direct summer sun in North Texas regularly exceed 140°F.
- Overvoltage damage: Solar panel voltage in full sun can spike above the controller's input rating if panel wiring is damaged or if panels are wired incorrectly after a repair.
- Age-related capacitor failure: The electrolytic capacitors inside most charge controllers have a finite service life, typically five to seven years under normal conditions and shorter under high-heat cycling.
Preventive practice: check controller enclosure ventilation annually. Confirm the controller's model-specific temperature rating. If your boards are more than five years old and have never had their charge controllers replaced, factor that into your next-season budget. Wanco and Ver-Mac both stock OEM replacement controllers for current-production boards.
Mast Lift System Failures
The telescoping mast that raises the arrow board or message board panel to operating height runs on either a hydraulic actuator or a manual crank-and-lock mechanism, depending on the unit model and vintage.
Hydraulic mast systems fail in predictable ways:
- Cylinder seal wear causing slow creep-down during operation
- Contaminated hydraulic fluid (water intrusion is common when the reservoir cap is left loose or the breather seal fails)
- Pump motor failure, typically from corrosion at the motor's electrical terminals
Manual crank systems fail differently:
- Cable or chain wear on worm-gear crank mechanisms
- Corrosion seizing the mast sections, preventing smooth travel
- Locking-pin wear that allows the mast to release under vibration
A mast that doesn't hold elevation reliably is not just an inconvenience — it's a visibility hazard for approaching drivers and a compliance issue on any project where board height is specified in the traffic control plan.
Preventive practice: exercise the mast through its full travel range during every monthly inspection. Lubricate mast tube seams with the manufacturer's specified lubricant — typically a dry PTFE or silicone spray, not grease, which attracts dirt and accelerates wear. Inspect hydraulic fluid level and condition on each monthly service. Replace hydraulic fluid and check cylinder seals every two years regardless of apparent condition.
Water Ingress in Control Modules
The control module — the unit that drives the board's display patterns, manages operational modes, and interfaces with the operator controller — is designed to be weatherproof, but weatherproofing deteriorates. Gaskets compress and lose elasticity over years of thermal cycling. Fasteners back out slightly, breaking seal integrity. Cable entry grommets crack.
Water in a control module causes failures ranging from intermittent display errors to complete board lockout. The insidious part: water ingress often doesn't cause an immediate failure. It causes corrosion over weeks and months, and the board may pass a quick function check the morning after a rain event, then fail unexpectedly two weeks later when corrosion progresses to a critical trace or connector.
Preventive practice: inspect all module enclosure gaskets and cable entry points during annual service. Replace gaskets that show compression set (the gasket doesn't spring back when pressure is released). After any board is rained on heavily or driven through a wash bay, open the module enclosure and inspect for moisture before returning the board to storage.
Trailer Hub and Bearing Failures
The trailer that carries the arrow board gets towed at highway speeds across the system, often by operators who don't think of it as a piece of equipment requiring attention in its own right. Trailer wheel bearings fail from inadequate lubrication, water contamination of grease (especially from pressure washing), and the inevitable fatigue of high-cycle rotation.
A failed trailer wheel bearing is a roadside event that takes the board out of service immediately and creates a safety hazard for both the crew and passing traffic. On a highway shoulder, it's a serious situation.
Preventive practice: repack or replace trailer wheel bearings on a defined interval — typically annually or every 12,000 miles, whichever comes first. Use a water-resistant grease specified for trailer applications. After pressure-washing trailers, inspect hub covers and grease seals for breach. If a board's trailer has rubberized Dexter-style torsion axles, inspect for torsion-element cracking on the same annual schedule.
Building a Preventive Maintenance Calendar
Most of the failures above are predictable and preventable with a structured inspection calendar. A working PM schedule for trailer-mounted arrow and message boards:
- Before each deployment: function test all display segments, verify mast extends and locks, check trailer lights and connections
- Monthly: inspect connector condition, check battery charge state, exercise mast, check tire pressure and visual tire condition
- Annually: inspect and treat LED connectors, inspect charge controller and enclosure ventilation, repack or inspect trailer bearings, inspect module enclosure gaskets, inspect mast tubes and lubricate, full battery load test
- Every 5–7 years: replace charge controller proactively regardless of apparent condition
Boards that get this level of attention stay on the shoulder instead of the shop. The labor cost of a structured PM program is a fraction of the cost of a mid-project board failure — particularly on projects where a replacement board isn't readily available in your region.
Talk to Us
If you're dealing with a board failure in the field or want help building a PM schedule for your arrow board fleet, call us at (940) 600-5131 or use our contact page — our shop handles traffic-control equipment maintenance alongside our truck work.