13

If it is a 21W/5W bulb, then it has 2 filaments of different brightness. The 5W filament is for the side/tail light for night driving. The 21W filament is for bright illumination when you press the brake pedal. Image copied from ToolStation


7

The tail lights on this car look like: (image source) The outer assembly is the one on the quarter panel: The inner assembly is the one on the trunk: I'm 99% sure of this, but note that it is the result of a bunch of Google searching, and generic product pictures on parts sites make finding a clear image confusing. If somebody could confirm this that'd ...


7

Taillight - Generic term that could refer to any part of the assembly or the bulb. Context required. (i.e. "your taillight is cracked" = lens, "your taillight is out" = bulb, "insert the bulb into the taillight" = forward shell, etc.) Taillight Assembly - The entire taillight, including the lens. Strictly speaking, this excludes bulbs. A manufacturer list ...


6

The parking lamp/headlight switch applies power or ground so the circuit would be open if you were testing with the switch off. Same with the turn signals. The tail lights are on separate circuits. They don't share a ground. Does the car have an aftermarket trailer harness? If not your going to have to remove panels and visually inspect the harness for ...


5

I'm going to answer this in a general way because for someone to tell you what the wires mean, they would need to follow this procedure, or have access to detailed wiring diagrams for your car. You'll need a multimeter for this, and you'll have to take apart the brake light as if you were changing the bulbs so you have access to the bulb sockets. I'm ...


4

Remove the tail light bulb then hit the brake and see if it still blows the fuse. If the brake light works, then the combined bulbs is too much for the fuse. Check the wattages of the new bulbs. If it still blows remove both bulbs. If it still blows you could have a short in the housing. Re-install the old one to make sure you didn't introduce a short in ...


4

Its a mixture is tradition and function. Red has been used to signify "Stop" much longer and in many more applications than just motor vehicles. Stop and Do-Not-Enter signs are used everywhere. Possibly, although I can not confirm or cite a source, in history blood was used to mark doors and entryways that should not be entered and therefor the red color ...


4

I'm assuming that you are testing the brake bulb voltage with the brakes actuated. There is high resistance somewhere in the circuit causing a voltage drop. For example lets suppose there is 10k ohm of resistance in the brake light switch. When the bulb is out and the switch is activated there is no current flow. A good meter has 20M ohm of resistance and ...


4

The most common way to handle this will be rubbing compound and preferably a power drill or buffer. If this is a tail light it is likely a plastic of some kind. You can polish out minor surface scratches with rubbing compound and a buffing wheel. This of course depends on if this is a scuff or what most would call a scratch. If the depth is significant ...


4

Blue Green is the indicator wire for the left rear, blue brown for the right rear. Assuming USDM.


4

The ABS light is an indicator of an error caught by the ECU. It usually is an error for a defective ABS sensor or a related brake issue. It's difficult to tell what exactly it is without reading the error code. Some specific problem might be fixed by reprogramming the ABS module, others won't. Depends on the issue and the year of your 528i. Once you get the ...


4

As @fred_dot_u said, test to see if the lights will go off if you raise the brake pedal up with your hand/foot. If so, it's likely that your brake pedal switch needs to be adjusted, or less likely it is defective. Adjust your brake pedal switch. https://www.yourmechanic.com/article/how-to-replace-your-brake-light-switch-by-spencer-cates Making an free ...


3

Break out the multimeter. Start at the bulbs. Verify the ground is good and then and work your way back towards the fuse box looking for an open as long as the wiring is accessible (Have a friend / brick depress the pedal). Assuming you haven't found the trouble spot, move to the fuse box and go the other way. If you're lucky the problem will be where you ...


3

If you are looking to figure out which wire goes to which, an easy way to figure this out is to have a source which produces 12vdc and has the two leads for (+) and (-) with probes attached, plus a pad and pencil to mark down what is what. After you have your 12v source and other supplies to get started, take the bulb section out of the housing so it looks ...


3

Blowing a fuse is a pretty good indication of a short circuit. If you have a DMM (digital multi-meter) try some basic tests: With the fuse out, read between the prongs of the fuse socket and ground (a nearby screw or other bare metal) with the meter on a DC Volts scale (20 VDC is common) to identify the hot side of the fuse. Once you know which side is hot, ...


3

You may be able to extract the screw by "drilling" it out with a left-handed drill bit running in reverse (counter clockwise). If you're in the US you can get a relatively inexpensive set from Harbor Freight. This YouTube video shows the technique. The original recess for the driver will give you a good center for the bit. Before starting I'd spend some ...


3

Have you damaged the start of the thread - easy to do on plastic threads. Dress the end of the thread with a small file and make sure it is clean, then it will normally go in.


2

I had the same problem, turned out to be the green / white wire on the right rear cluster. Simple easy fix.


2

If you look in the trunk near the taillight you will find some plastic screws that hold the carpet in place. Using a flat head screwdriver remove them by unscrewing them or prying them out. Moving the carpet should reveal the mounting bolts for the taillight. It will most likely require a 10mm deep socket to remove the nuts. Disconnect the lamp sockets from ...


2

There are LED bulbs with ballast, or you can purchase ballast separately to keep flasher units happy. http://www.superbrightleds.com/carbulb_notes.php#turnsignal


2

The first place to look for the headlights would be the fuse panel(s). Often there are two: one inside the passenger compartment, either at the driver or passenger kick panel or on the side of the dash where the door covers the dash on the driver side. The other is the engine compartment (in a black plastic box--diagram will be on the inside cover or on the ...


2

I did finally figure this out. The newer Focus uses CANBus to detect bulb and circuit faults, so the brake light circuit ALWAYS has 12v going through it, with a clamped amperage to prevent the bulb from illuminating. When you press the brake pedal, the "clamp" goes away, allowing the bulb to glow. The other factor, is the car's BCM detects load on the ...


2

You're exactly correct in that thinking (I replaced the bulbs in my old Volvo once and it caused it to think they were out because the bulb was slightly different (these weren't even LED's; just a different filament or connector or something, I forget; no tolerance at all on that circuit). I don't know if there's a standard way to fix this (other than use ...


2

As a general rule, your new bulb should be in good working order. Just to make sure swop it with the matching bulb on the other side of the vehicle which you know is definitely working. If this bulb now operates in the first lamp assembly you now know the problem. Turn your ignition on off when you check the bulb for working as some vehicles use this as a ...


2

The Society of Automotive Engineers (SAE) does not define regulation, it reflects it. In the United States the Code of Federal Regulations defines the rules for general safety in automobiles. In this case case, the DOT (Department of Transportation) has defined this framework and has published it in the CFR's. Here is a link for the CFR (Code of Federal ...


2

If this is an E39 or E60 chassis, you should be able to use GT1/DIS or INPA to probe the computer and figure out what is setting the ABS light. There are a bunch of possibilities that might cause this, including: lack of wheel speed sensor signal failed seals in the ABS unit failed solders (usually microscopic cracks) that prevent the solenoids from ...


2

Ok, time to get serious here :-) Do you have access to a test light or a DMM (or a volt meter of any sort)? It would be good to start by looking at the evidence – if you still have the old bulb, does it look good (clear glass, with both filaments connected to their "arms" on both sides)? Are you sure you've got the right bulb? Has anything happened ...


2

To remove the light assembly you remove the two bolts in your first picture. That white plastic thing in your second picture holds a metal stud that's threaded into the light assembly. You need to carefully pry it out while sliding the assembly towards the rear of the car.


2

There isn't a serviceable relay for the tail lights, all exterior light controls are built into the Smart Junction Box. If your license plate lights and rear side marker lamps work, than take a look at your connectors again and see if you have power and ground. Make sure the bulbs fit snuggly and make contact with the terminals in the connector. All the ...


2

Check the fuse. If it still good, you will have to check to make sure it has a good ground and that no wires are broken. Without a multimeter and schematics, its going to be harder to find your issue. By basic tester, do you mean test light?


Only top voted, non community-wiki answers of a minimum length are eligible