DEAR MIKE: I have a set of Malibu lights in my back yard and several of them don't work. I have changed the light bulbs, but still there's no light. It seems to me that replacing the entire system is a big chore. Why is there no light? -- Ken G.
DEAR KEN: You don't need to replace the whole system. Like so many projects, you will have to determine the problem first and then fix it. Allow me to show you the light.
The simplest fix is to change the light bulbs, but since you have already done that we will move on.
Use a low-voltage tester (about $12 from a home center) to test that the light bulb receives power. The tester will have two terminals. Manually turn the lights on and stick a terminal in both sides of the light socket. You may have to place a piece of black duct tape over the light sensor if the transformer doesn't have a manual switch.
I say "light socket," but it doesn't look like one. This socket will have either two holes, or two clips depending on the system. If the tester indicates you have power to the socket, then you have a bad bulb. You can also use the continuity-testing feature on the multi-meter to test the bulb.
If you aren't getting any power to the socket, you will need to dig up the light base assembly. This assembly contains the socket, the wiring that connects the socket to the underground cable, and the stake that holds it all in the ground. The entire assembly will only be about six inches deep, but dig it out carefully as you don't want to sever the cable.
You want to find where the light assembly connects to the cable. In many cases, this area corrodes or gets clogged with dirt preventing electrical contact. Unscrew the connector or pull it apart, then clean it off with a soft brush.
At the ends of the light assembly's wires will be sharp contacts. These contacts are pushed into the cable to provide electricity.
Use the continuity tester by touching a terminal to both contacts. If the light assembly is good, the tester will show continuity. If there is no continuity, replace the light assembly (between $12 and $25).
If the light assembly tests fine, then re-install the connector into the cable. It is possible that the contacts have either pulled away from the cable's wiring or that dirt has prevented the contacts from touching the wires. Clear away any dirt, then re-install the contacts into the cables. The connections are secured by either twisting on a retainer cap, or by pushing the contact wires together until they lock in place.
Had the entire system been dark, you would have first checked that the transformer was getting power from its source (typically a GFCI outlet). If it was not, then you would need to backtrack from the GFCI outlet (try pushing the "reset" button on the outlet).
If the transformer were receiving power but not delivering it to the lights, you may have needed a new transformer. Many transformers have a circuit reset button. Try pushing the button before you buy a new transformer.
If all of the lights work up to a certain point and the rest of the lights are not on, you may have a damaged cable.
In this case, start by digging up the first light assembly that doesn't work and pull the contacts out of the cable. Manually turn the system on and stick the tester in the holes of the cable that the contacts made. If you get power from the cable, the problem is somewhere in the light assembly or bulb.
If there's no power, dig up the cable between the last operating light and the first nonoperating light. Find the damaged area of the cable and splice a new section of cable in its place. New cable and splice connectors are available at most home centers.