For some people, relaxing in a hot tub is a total sensory experience, with surround sound and a soothing light display to complement the warm, relaxing water. LED lights are sold as part of some hot tub packages or can be added later. As with any electronic gear, they can break down over time. Troubleshooting may discover a problem that can be fixed instead of having to replace the entire package.
Check the main circuit breaker box to ensure the breaker hasn't tripped. Pull on the transformer's electrical plug to ensure that it is securely in place. It sounds simplistic, but many times the plug can be loose enough to prevent a complete circuit without being visibly noticeable. If the plug is in the wall socket securely and the lights still don't work, then unplug it and the hot tub before taking any further steps.
Check the transformer, the switch, the wiring and the lights one by one. Concentrate on one area at a time and ensure it is working correctly before moving onto another area.
Hold the transformer in your hand and plug the LED lights back in. The transformer should feel warm after a moment but not so hot that it burns you. If the transformer feels excessively hot, it may be malfunctioning. If there is a burnt odor coming from inside, then the transformer is likely bad. If the transformer is the type that opens, then unplug it from the wall, open the lid and look inside. There may be one or two fuses inside that are burnt out and need to be replaced. Examine the fuses carefully for any bulges or discoloration; both indicate a bad fuse. If you think a fuse might be bad, replace it.
Open the switch holder to examine the wiring. Look for any breaks in the wires that connect to the switch, rust in the circuit or where two bare wires may be touching one another. Problems in the switch prevent the lights from receiving power.
Follow the wiring and look for areas where it is excessively bent, crimped or squeezed between two hard objects. Low voltage LED lights have thin wiring that easily breaks when stressed. If the insulation has scraped away, it may create the conditions for a short, especially around water.
Look for discolored or cracked LEDs and replace them. A loose LED can disrupt the power for all lights past that circuit so firmly press each light into place.