How to replace a chain-drive garage door opener RPM sensor

Use a step ladder to access the garage door opener’s power cord and motor unit.

Unplug the garage door opener.

Position a work table near the area under your motor unit to hold the garage door opener during the repair.

Pull the emergency release rope to release the trolley from the garage door.

Shut the garage door if it's not already closed.

Remove the fastener ring from the straight door arm connected to the outer trolley.

Pull out the clevis pin while supporting the straight arm to disconnect the garage door from the outer trolley.

Lower the straight and curved arms down and rest them against the garage door. Use a helper if necessary.

Open the light cover to access the wall control and safety sensor wires connected to the motor unit.

Take a digital photo of the wall control and safety sensor wires connected to the motor unit. You'll refer to the photo later when reconnecting the wires.

Disconnect the wall control and safety sensor wires from the motor unit.

Close the light cover.

Remove the nuts, bolts, and lock washers that secure the motor unit to the ceiling bracket. Support the motor unit with one hand as you remove the last bolt from the ceiling bracket.

Carefully lower the motor unit down and rest it securely on top of the step ladder.

Climb down the stepladder, lower the motor unit down and rest it on your work table.

Move your stepladder by the garage door so you can remove the rail from the header bracket.

Remove the fastener ring from the header bracket clevis pin.

Pull the clevis pin out of the rail and header bracket while supporting the rail with one hand.

Lower the rail and rest it on a rung of the stepladder so the rail is level with the motor unit on your work table.

Remove the light covers and light bulbs from the motor unit.

Flip the motor unit over, remove the screws from the motor unit cover and pull the cover off.

Unplug the RPM sensor wire harness.

Remove the interrupter cup from the motor shaft.

Release the RPM sensor from the mounting clip and remove it.

Push the new RPM sensor into the mounting clip, locking the sensor into place.

Connect the RPM sensor wire harness to the new sensor.

Reinstall the interrupter cup on the motor shaft.

Reinstall the motor unit cover, securing it with the mounting screws.

Reinstall the light bulbs and light covers on the motor unit.

Reconnect the rail end to the header bracket using the clevis pin and fastener ring.

Position your step ladder under the motor unit ceiling bracket and carefully set the motor unit on top of the step ladder.

Climb the step ladder and reinstall the motor unit to the ceiling bracket using the nuts, bolts and lock washers.

Open the light cover to access the wall control and safety sensor terminals on the motor unit.

Using your digital photo for reference, reconnect the wall control and safety sensor wires to the motor unit.

Close the light cover.

Reconnect the straight door arm to the outer trolley using the clevis pin and fastener ring.

Re-engage the trolley.

Plug in the garage door opener.