2013 honda accord low beams and fog lights don't work, high beams work. checked fuses, all look good, looking to replace relay switch but can tell which on is the headlight relay

Disconnect one of your headlamps and use a multimeter to figure out the positive low beam and ground on the wiring, then using the ohm meter function check the high beam wiring back to the fuses and relays.
If I remember correctly, the fog lights are supposed to turn off when you turn on the high beams. So that switch system may need to be looked into on the controls.

one wire will for high beam
one wire will be for low beam
the last wire will be ground wire
as fog light have only one beam you can use the low beam wire and parallel wire it to the fog lights
that way you have the head lights still and the fog lights as accessories correctly wired according to regulations
how to do it simply-- find the low beam power wire ( light switch on low beam and power at the light bulb check ed with a multi meter set on volts
solder , piggy back, or double plug in a connection into that wire and run one wire to the left fog light and one to the right fog light connect each fog light to an individual ground wire and connect those wires back to the ground wire for the main lights
Now having done that simple addition to the lighting system another problem has come up
The wiring will now be too light to carry fog light current and or the light switch will burn out
To over come this problem, the circuit needs a relay
fit a relay on the bike and now run the low beam wire to a terminal of the relay
run the other terminal wire to ground
this enables the relay to operate when the low beam is switched on but at this will not switch on the lights yet
now you have to run a heavy gauge wire (fused at the battery) to one of the power terminals of the relay and from the other power terminal to the connection for the fog and low beam lights
Now it all works switch on the high beam and no for lights
change to low beam and the fog lights come on as well
All nice and legal
Of course if you don't care about being legal just buy a 30 amp toggle switch and run a fused wire directly to the switch from the battery to the lights and then to ground from the lights
You will know that the generator / alternator for the bike will not be able to run the fog lights with or without the main lights so what will you have achieved

Your fogs only working when low beams are on is normal, as far as your low beam lights not working, I would have the headlight switch checked, or check for a bad fuse or possibly a relay if your car has a light relay. Some do and some don't, I am not that familiar with your model of car to tell you for sure.

I suspect it is the headlight switch

Check the relay that powers the high beam, if memory serves me the relay is shared between those two circuits.You can swap the relay with a known good relay to prove if that is the issue.

The high and low beam lights use the same power source, so if the low beams work the high beams have power.
There is a low and high beam relay controlled by the dimmer switch.
If the low beams work and the high beams don't, and the bulbs are good, check the dimmer switch and the high beam relay.

if the fuses are good then you need to check for power and ground at the headlight plug that attaches to the headlight bulb if you have a good power and ground there and the connections are good then the bulbs are both no good.or if you can tell the bulbs are burnt out by looking at them then you don`t have to check powers and grounds.you also can directly feed power and ground to the bulb and check both the terminals for high beam and low beam as you cannot tell which is which by looking at the terminals

OK, you need to connect a relay to one of the 'power' wires under the hood that leads to the bulb of the low beams. Then, the fog lights will go on only when they are turned on or off.

Otherwise, you could have a relay that is controlled by a switch that independently operates the relay and thus the fog lights.

Both methods are legal in, Pennsylvania, anyway.

Sometimes hooking up the relay to the fuse box will only turn the fog lights on if the ignition switch is turned on for switched fuse box contacts. And, sometimes, hooking the relay to the fuse box will keep the fog lights on all of the time, as the fuse box may be energized at all times at certain contacts.

Good luck on installing your fog lights, correctly.

do you have low or high beams?

LOW BEAMS: When headlight switch is turned on the headlight relay is energized providing voltage through fuse 37 and 38 to the headlights and the low beams come on.

HIGH BEAMS : same thing as above thru fuses 37 & 38. When the dimmer is in high, the dimmer relay provides ground to the high beams, and the high beams come on.

1. pull your flash see if lights come on?
2. check fuse 15 if good
3. check fuses 37 & 38.