Rodent Damaged Wiring and Opener Repair

The Fault Nobody Traces Back to an Animal

A garage door that has started closing halfway and then running back up, with no obstruction and no pattern to it, is one of the more frustrating things to diagnose. The sensors get realigned. The sensors get replaced. The opener gets replaced. Six weeks later it is doing it again.

The cause, more often than people expect, is thirty inches of chewed wire behind a storage shelf.

Why the Sensor Wire Is the Target

Since the early nineties, every residential opener sold in the United States has had to provide entrapment protection under UL 325, which in practice means a pair of photo eyes mounted low on each track, about six inches off the floor. They are joined back to the motor head by two conductor low voltage wire, usually a light gauge bell wire, and it is normally stapled along the wall at skirting height because that is the quickest place to run it.

That is precisely the route a rodent takes. They travel along walls rather than across open floor, the wire is soft, and the insulation is exactly the sort of thing that goes into a nest.

Once the insulation is gone, the two conductors touch each other intermittently, or the strands corrode and open up. Either way the opener reads a sensor fault. Its safety logic is designed to be pessimistic, so it refuses to close, or it closes and reverses. The lights on the motor head blink a code that says beam obstructed, and the beam is not obstructed.

The Test That Sorts It Out

Disconnect the sensor pair at the motor head and bridge the two terminals briefly. If the opener stops complaining, the fault is in the run rather than in the eyes. From there it is a matter of following the wire.

We do not simply repair the damaged section and staple it back on the same line. A rodent that found that wire once will find its replacement, so the new run gets rerouted higher, or sleeved, or taken through conduit where the route cannot be changed.

The Opener Head Itself

The motor housing is warm, dark, enclosed, off the ground and undisturbed. As far as a rat is concerned it is ideal, and the space behind the light lens is a common nesting spot on chain drive units in particular.

The nest is not the expensive part. Urine and droppings on a logic board corrode traces and connector pins over a few months, and a board that has been sitting in that is on a short clock. When we open a head and find that, we say so, because there is no point charging for a sensor repair on a unit that is going to fail regardless.

If the opener does need replacing, note that in California, under SB-969, any residential opener sold or installed since July of 2019 has to have a battery backup so the door still opens in a power cut. That is not optional and it does affect what a replacement costs.

Other Wiring in the Same Garage

While we are in there we look at the wall button run, the antenna wire hanging from the motor head, and any low voltage cabling for lighting. All of it is the same gauge and the same appeal. Finding one chewed run and stopping there tends to mean a second call out.

The Order We Work In

Wiring repair without exclusion is a repeat visit waiting to happen. If the perimeter is open we will tell you, and we would generally rather seal the garage on the same visit than come back to the same fault in the spring.

Call (562) 689-5506 and describe what the door is doing and what the opener lights are showing.