Both low beams have gone out on my 2004 BMW Z4 3.0. I have checked fused in glove compartment and all are OK. Someone mentioned checking the headlight relay under the hood. I don't know what I'm looking for. Any Help?

could you check the low beam headlight fuse and relay. It is normally near the battery compartment or under the steering in the cabin.

Try switching the hdm relay with the fan relay in the engine compartment fuse box

Someone would need to check for voltage output on the dimmer switch for low and high beam.

If the lights are switched then the switch controls a rely all lights are switched on bmw. Can use fog lights temporarily. Find rely test with continuity meter when on, disconnect lights first, then turn on lights switch, check for 12v at light bulb terms, if 12v then bulbs bad, if not relay is bad, test with continuity meter, rely should read 0 ohms when lights switched on, infinite open circuit when switched off. If lights work in manual switch pos then solar sensor bad.

I would check them electrically, not by looking, that way you can see if they are getting power in and out. Then at the bulb, see if you are getting power AND ground. Ground wires are White/Black

Check fuse box in engine bay (should be near battery) inside should be the fuse for high beam and low beam.

Check the fuse. There are seperate fuses for right and left. You dont mention if the high beam works for that side? If it does, the fuse is good. The GREEN wire at the bulb is the ground for the low beam. If that wire has power, then the ground is bad. If the high beam works, the hi'lo beam switch is good, and there is a problem between that headlight and the Engine Compartment Junction Block

remove the air filter housing ,simple .this programme has a spell check thingy working and its driving me nuts ,it cant identify plain english ,write colour and it squiggles it out but color is ok .

check fuses under hood there should be seperate fuses for each side.

locate the relays that control those things on the engine compartment fuse box located near the battery... replace them

Robert