Missing fuse box cover and need to check fuses for headlamp problems..Recently replaced both headlights. Don"t know which fuse to pull

I saw what you replaced. Did you do any testing, first? Anything electrical, always check voltage and ground for the component. Use a testlight.

There are right and left headlamp fuses in under hood fuse box. I doubt the fuses blew, but, you can check voltage at fuse circuit with headlamps on.
I don't know if there would be any applicable codes for headlamp system? You can check.
Your bcm has some control over headlamps.

A lot of systems now work on grounds...it's good that you have power, however if there is no ground then the light will still not work. What car do you have?

Does the vehicle have daytime running lamps ? Did you pull fuse from the inside the vehicle fuse panel ? I/P Fuse # 12 30 amp underhood fuse box is for the headlamp switch . Sounds like daytime running lamp module is the problem . But , without testing this is just a guess , by looking at a wiring diagram . Do you know what a automotive electrical wiring diagram is ?

There is a fuse box under the hood on the passenger side remove the cover and the #10 fuse is for the headlamps. Look on under side of cover for fuse #s.

Wish I had like an owners manual that just give a layout and what the fuse is for. I don't but found some stuff I did have that may help. I hope it does for your sake. It looks like there's a couple of fuse boxes and relay boxes. Th first picture (below) is a picture of a relay box located in the engine compartment. You should be able to tell if it's the right box by the layout. It looks like in the number 5 position there is a 10 amp fuse but that seems to cover high beams (see description in next picture below). Then there is a multi purpose fuse box and going to gues that's inside the vehicle but when you find it you will be able to tell it's the right one by the layout (see next picture). In the number 10 position there seems to be a fuse that covers the headlights but only if you DON'T have anti-theft. Description of the fuse layout is in the next picture. Then there is the headlamp relay itself. It's located in the relay box somewhere in the engine compartment but again you will be able to tell it's the right one by the layout (see the next picture) It looks like the headlamp relay is in the A-01X position. Wish I could be of more help or at least not having to be so detailed but all I have is the factory service manual. If you do need anymore information please don't hesitate to email me at [email protected] with detailed questions so I can send the correct information. I hope this helps and good luck. here's your pictures.

check under the hood for black box,lift the cover off of black box,marked" main fuse and relay boxfuse positions should be marked on underside of the lid to main fuse panel box,that you have just removed.check for a blown headlamp fuse in that box. it's either a blown fuse in that box,or if only one headlights "out" it will be a blown bulb(headlight bulb) it's very unusual for both headlight bulbs to blow at once. so in saying that,look for a blown headlight fuse. thank you for choosing fixya.com.

There is a main fuse/relay box located under the hood. It may be on either side of engine compartment. Remove the cover and locate the fuses/relays. Each section should be marked as to what each fuse/relay is for. Typically, there is either a fuse or relay for each headlight. They are usually marked with the letters LH (left headlamp) or RH (right headlamp). If there are fuses under each heading, check fuses with a fuse tester. If you do not have a fuse tester, simply remove the fuses and check to see if it is blown. If the fuses are good, the next step would be to check the relays. To do that, with engine and key off, remove a relay from another section (check to make sure the prongs match) and insert relay into headlamp relay socket. If headlamp comes on, simply replace the relay. If the problem still exists, have it serviced by a qualified mechanic certified in automotive electrical systems. I sincerely hope that I was of some help with your problem. Please feel free to let me know of your progress with this situation. Thanks.

Duralast / Relay - Headlamp Part Number:
20601 Autozone: $39.99 I had the exact problem with my 2004 Envoy. You need to replace the Headlamp Relay. This is a very simple fix. The relay is located under the hood in box just above the battery. Pull the cover off of the box, look at underside of box to see layout of relays/fuses, i do not recall the exact abbrevaition used for the headlamp relay but there are only two relays in there that look like the one you need, just play with those two and you will get it. Do not take it to the shop, my wife took ours in and they charged us way to much to diagnose such a simple fix. You can test it before you buy the part by switching the relays that are the same around and seeing if your headlights work (they will). It is as simple as changing what looks like a big fuse.

Best way is to check them all. If one is blown replace it if they are all ok then the fuse is not the problem. Cheers