Why would the speakers buzz when the lights are on?

Answer 1

You have a ground wire problem. You must make sure your stereo is grounded properly if not, you will get humming, noise , When the lights go on the Wipers, ETC. Find Another Ground for your radio and see what happens. it can help if u put in a filter but i would try running the ground out to the battery. If still buzz move the poss out too. (put a fuse from the bat. to protect that long of a run I had this problem in my 1998 Toyota Sienna with AM/FM/cassette radio and single disc factory CD player (separate unit). The speakers would buzz when the headlamps were on, regardless of sound system mode (radio, cassette, CD). Everything operated normally except for the buzz. Buzzing was intermittent and sensitive to jarring of the dash around the radio. I discovered the 12-pin plug for the CD was not fully seated in its socket at the back of the radio. The CD unit has a light that comes on with the headlamps and dims with the rest of the dash lights. I don't remember if the light in the CD player illuminated with the headlamps when the buzz occured, but it seems likely an intermittent connection to this circuit was the culprit. The fix has been "solid" for several months now. The last thing you want to do is extend any ground wires. It will only allow more noise problems! I am not sure how 'running the ground out to the battery' is much of an answer at all. Keep your grounds as short as possible, as large of diameter wire as possible (within reason for the load) and be sure it has good metal contact to the vehicle chassis. Many times with high current demands for amps, I will drill and clean 5/16" hole in the body for the ground then use a bolt and nut going thru the body to assure a long lasting and trouble-free connection. As stated, do check ALL connections including molexes, line level RCA's and grounds. Dr. DB Retired IASCA Pro 251-500 watts 1986-1994 Yeah man sounds to me like u have a bad ground or a loop in it somewhere.....check the whole wire for and bare wire or cuts.. it seems like the other answers are right but you might want to check for: shorts, bare wires, and bad connections to the rest of the car.