Wall console LED flashes three times and opener will not run or stops immediately.

Safety first: Disconnect power to the opener before handling any wiring at the head unit.

• Inspect sensor wiring along tracks: Look for crushed, pinched, or cut wires where they run along the vertical tracks or wall. Repair or replace damaged sections using low-voltage bell wire and wire nuts or crimp connectors.
• Check connections at sensors: Remove each sensor from its bracket. Inspect the back where the wires connect. Tighten loose screws and ensure no bare copper is touching the bracket or each other.
• Verify polarity: Wayne Dalton sensors typically use two-conductor wire; ensure the same color wire goes to the same terminal on both sensors and at the opener head.
• Dry out moisture: If sensors are exposed to sprinklers or rain, moisture can cause internal shorts. Dry the housings and consider replacing if condensation is visible inside the lens.
• Test by temporarily removing sensors: With power off, disconnect both sensor wires at the opener. Restore power. If the F3 indication clears, the fault is in the sensor loop. Replace the sensor pair if wiring checks good.