Bmw x5 2003 , rear brake lights always on ( not the center one) , horn does not work , radio does not work . this all started with I had to jump start my car

Question edited for clarity, 'fuse', unless you light it 'fuze'.Question moved to sub category.

If the radio has an inline fuse, it will be within 82 of the plug at the rear. They are built into the harness. Unlikely because there are three fuses covering audio.

https://fuse-box.info/isuzu/isuzu-trooper-1992-2002-fuses-and-relays

C11 10 (AUDIO[ACC]) MIRROR Audio, Door mirror, Door mirror control SW, Door mirror folding SW, Digital clock, Speaker C12 20 CIGARETTE Cigarette lighter C13 10 ANTI THEFT Anti-theft controller C14 15 STOP A/T CONT Stoplight SW (w/o cruise control), Brake SW (w/cruise control), Rear wheel anti-lock brake controller, Stoplight, Transmission control module, Electronic brake control module, Trailer harness connector, Cruise control unit, A/T shift lock control unit, Lockup off relay C15 20 AUDIO[BJ] Horn, Horn relay, Horn SW, Hazard warning light SW, Flasher unit, Anti-theft horn, Hazard warning light, Audio C15 20 TELEPHONE Telephone C16 10 CLOCK[B] ROOM Digital clock, Audio, Dome light, Map light, Luggage room light, Courtesy light, Door SW (Front, rear, tail gate), Antenna, Anti-theft controller, Key remind SW, Seat belt, Key & light remind buzzer

There should be 2 +12V supply wires. One is always on even when ignition is off. Another will be ON when the key id turned to ACC position. The radio fuse usually control the ACC supply. Check the function of the following items on the car.- Hazard switch. Horn. Brake lights. Rear lights. Room lights. If any of them them does not work replace the fuse and the radio supply will be available. It also shows that the supply for the radio is tapped from one of those circuits. If you know how to check with a test light. Check all fuses that should have supply even when ignition is off.

Check the brake fluid level before you go any further ,that light signifies low brake fluid

bad english accepted i come from the east end of london originally where english is the third language ,so what iam reading here is you have a problem with horn and the lights ,Now on this model if my memory serves me correct the brake lights will come on with the handbrake on ,but if its a auto version then the brake lights could be affected cruise control and what i think without a look myself is that the wires on the bottom of the steering wheel for the cruise and the radio horn ect run through the steering column and somehow they are damaged or twisted up and the only way is to remove the steering wheel to have a look ,to do this you must disconnect the battery first because if the airbag goes off accidently and your head is in the way then your dead .To get the stering wheel off you will have to remove the airbag unit first ,think its two torq 20 screws but it could be a 7mm headed nut ,remove the airbag then unplug it and then you can undo the big nut in the middle ,cannot remember the size of the nut though but once its off then the steering wheel comes off but its on a splined shaft so it may need a puller to get it off but i often use a piece of wood under a spoke and hit it with a 2kg hammer ,doesnt always work first time but normaly it does then you will tracks for the different controls .

The horn and rear brake lights are on the same fuse. Eventually the horns rust out like on my 1998 CRV. Once I replaced the horns, I could put in a new fuse without it blowing every time I sounded the horn. Problems still remain, namely: the cruise control does not engage and the remote start only starts the engine that runs for two seconds then dies. Still looking for an answer. It's a "Code Alarm" with Codestart dated 11/24/99.

LH/RH lights cable could be disconnected anywhere, will take a long time to trace.
Center Brake Light and LH & RH should be connected at one point.
Jump a cable from Center Brake Light to one of Rear Break Light.
Hope this will works.

Hi, Same problem - with my Hyundai Getz. Thought I'd pummelled the horn too much. However, I'm told that it might be the alternator. Battery completely died and couldn't be charged - AA man cleaned around the alternator ready for new battery, which seemed to work - advised to get new alternator. Didn't! Battery died again few weeks later, but still some power so that I can jump start the car - all lights on! ABS, airbag, brake - you name it! Also, car is brakig itself when driving - this only occurs when all lights are on. Lights eventually go off, and car resumes back to normal driving again - no more bunny hoping a it brakes, and no more smell of rubber. Have read that low power can be a problem for airbag light, and so checking battery, and alternator is a must. My alternator is now being ordered. Hope this helps. If it was anything else let me know.

do you have a alarm system in your car if so disable it
take out its fuse

Take your battery to the parts store and have them test it. If its an original replace it anyways batteries only have a 5 to 7 year life span. on another note when your window walked off they may have damaged a switch in the door. this may be causing your display issues.

check behind the brake peadle for a little button that pushes in and out when the peadle is pressed(this is your brake light switch) some cars have more than one of theese. manualy let the button out if the light works the switch is good if it does not disconect the harness from the switch and take a small piece of wire and jump the two prongs on the harness if the brake lights come on then you need a brake light switch. if this doesnt work check for power at the switch. if no power you have a bad fuse if there is power and you already jumped the wires to the switch then you have a broken wire between the switch and the tail lights.