Low beams not working. It is not a fuse.

I do not have any low beam headlights. I have checked the fuses and it is not them.
Experienced mechanics share their insights in answering this question :
Hello, Since you have covered the basics of checking fuses, I will assume that all the other lights illuminate including the high beams. Believe it or not, it is possible for both low beams to burn out at the same time. What can happen is when one low beam burns out, it will cause resistance in the overall circuit letting the other bulb absorb a slight spike, burning out the other bulb. I would recommend trying two new bulbs first. If you need help after that you might want to make an appointment with a mechanic to have the headlights system looked at.

How to Identify and Fix Common car Problems ?

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A bad headlight relay is among the more common reasons we see for low beam headlights not working while the high beams do. You see, the low and high beams each have their own relay, which is essentially an electrical switch. Like fuses, sometimes relays go bad.
All the electrical systems in your car, including the headlights, are protected with fuses. These are designed to `blow` and break the circuit if too much power comes through them.
If the relay has gone bad, it may be receiving the electricity but cannot complete the full circuit. This will require a new relay. Some vehicles have different relays for their high beams and low beam lights. If one relay goes bad, the other one may still work to power the light.
If just one bulb fails to work in either high beam mode or low beam mode, it may be the bulb. Most headlight failures that are limited to just high or low beams are related to a relay or the high beam control switch. Headlights work but seem dim. The cause: Foggy lenses, worn out bulbs, or a charging system issue.
Where is the Headlight relay located? You can find the Headlight relay in the electrical distribution unit of the engine block. In case you need support locating the relay, refer to your owner`s manual.
Headlight Problem 3: Wiring Troubles

In most vehicles, this includes a wiring harness and a fuse. These components provide the power needed to fuel your headlights. Wiring troubles can cause your headlights to dim, misfire, or stop working entirely.

When you turn on your headlights, that switch activates a relay. That relay, in turn, actually provides the electrical connection between your headlight bulbs and the battery. Fuses are also involved in order to provide a sacrificial failure point to protect the rest of the wiring.
Generally, you`ll have a standard halogen bulb for low beams, and then an HID bulb for your high beams. These are not interchangeable. Both require a different bulb (HID bulbs are significantly more expensive than halogen bulbs, as well).
Extreme Temperature

The filament needs to get hot to light up. However, if it gets too hot, the filament could melt and break, which would cause your car headlights to burn out. Excessive heat can also cause the glass to break, letting the filament burn out in the open air.

If you`re driving around in a vehicle that has only one working headlight, chances are an officer will stop you. This applies even if you are driving your car with two working parking lights illuminating the road. You can receive a citation for violating the law.
One of the most common symptoms of a faulty headlight switch is issues switching between headlight modes. If the headlight switch fails or wears out it can cause problems operating the headlights. A broken switch may only work on certain modes, or may cause them to come on and off intermittently and erratically.
In most vehicles, there is typically a single fuse for both headlights rather than a separate fuse for each headlight. The headlight fuse is usually located in the fuse box, which is typically located in the engine compartment or under the dashboard on the driver`s side of the vehicle.
Fuse terminals that are making poor contact, that could cause the fuse to heat up and blow – if the fuse takes a long time to blow (more than a few seconds) and the current drawn by the bulb is reasonable, then overheating is the most likely cause.
The two most common failure mechanisms of relays are contamination and mechanical wear of the internal switching elements discussed as follows: a. Contamination is a major cause of early life failures.
The only tool required to check a relay is a multimeter. With the relay removed from the fuse box, the multimeter set to measure DC voltage and the switch in the cab activated, first check to see if there are 12 volts at the 85 position in the fuse box where the relay plugs in (or wherever the relay is located).
Generally, you`ll have a standard halogen bulb for low beams, and then an HID bulb for your high beams. These are not interchangeable. Both require a different bulb (HID bulbs are significantly more expensive than halogen bulbs, as well).
So when you turn on your car headlights, a switch will activate a relay. This relay gives an electrical connection between your car headlights and battery. Your fuses are the elements that protect the rest of the wiring. You also will have a relay for your high beams.
Generally, you`ll have a standard halogen bulb for low beams, and then an HID bulb for your high beams. These are not interchangeable. Both require a different bulb (HID bulbs are significantly more expensive than halogen bulbs, as well).
Generally, you`ll have a standard halogen bulb for low beams, and then an HID bulb for your high beams. These are not interchangeable. Both require a different bulb (HID bulbs are significantly more expensive than halogen bulbs, as well).
It was once the norm to have separate bulbs for your high beams and low beams, but most modern cars have only a single bulb with two filaments on each side of the vehicle that performs the work of both the high beams and the low beams. There are a few different types of bulbs available.

Relevant Questions and Answers :

the most relevant questions and answers related to your specific issue

Both R&L low beam headlights quit working simultaneously.
ANSWER : Hi there. Check the switch to the headlights and see if there is a break in the wiring. Check the fuses and see if there is any fuse that are blown. If the fuses are good and there is no break in the wiring, then either the switch has failed or the ballast resister has failed on the low beam circuit. Turn on the switch and check for power coming out of the switch. If there is power to the switch and power out of the switch, then I recommend replacing the ballast resister. If there is no power coming out of the switch, then the switch needs replaced. If you need further assistance with diagnosing the low beams, then seek out a professional, such as one from Your Mechanic, to help you.

2007 Mustang Low-Beam headlight on only one side only comes on for 10 seconds then go outs, however high beams work fine!?!?
ANSWER : Hey there, thanks for writing in about your 2007 Mustang. The low beam circuit is monitored by the the Smart Junction Box. It’s the fuse box in the right kick panel. Basically what this means is if the resistance, or the current flow in the circuit is not within the specified range, it will turn off the power to it. That’s why you won’t find a fuse for the low beams. It will re-check the circuit every time the ignition key is cycled. The circuit flows from the SJB through the fuse box under the hood, and then to the headlights. Inspect as much of the wiring as you can. Especially where it might have been tampered with for the HID lights. If there is a short to power or ground, or too much or not enough resistance, it will turn off the power. This is not the case with your fog lamps and high beams. They are powered by a relay that is fused, and the circuit is not monitored. It will simply blow a fuse if there’s a problem. If you need more help, consider YourMechanic, as a certified technician from YourMechanic can come to your car’s location to diagnose and repair the headlight problem.

My dash board don’t work my front light work when I change my light into high beam and my back window won’t go down
ANSWER : As unfortunate as it is, your vehicle would be considered flood damaged. Diagnosing electrical problems in a flood damaged vehicle is nearly impossible. This would take many hours or even days to determine which wiring harnesses and circuits have been affected. Then nearly all of the wiring under the dash would likely require replacement as well as many sensors and switches. On a BMW vehicle, the amount of wires and switches are likely more than that of a lower end vehicle. Due to the inefficiency in cost, you would likely be able to purchase another BMW like yours for less than what it would cost to fix your car. Many insurance companies would consider this type of damage to total out the vehicle unfortuantely.

One of my car’s headlights does not work
ANSWER : Hello. There are 2 devices in the front wiring of your vehicle called "Signal Acquisition Modules." One is for the left side of the front, the other is for the right. They act as an electrical "router" and power distribution module for electrical loads up front. These modules take signal pulses from light switches and other controllers, and turn on power to the requested device.

The SAM units have fuses in them, just as a traditional box would. I would check the fuses in each SAM for both low and high beams, then check the igniters for the xenon low beams. If this seems a bit intimidating, I recommend having a certified mechanic, such as one from YourMechanic, come to your location to inspect for any electrical problems and suggest the needed repairs.

On the driver side of my car the low beam headlight doesn’t work. I checked all fuses and changed the bulb, but it still doesn’t work
ANSWER : Hey there. When you say you checked the fuses & the relays, and everything was getting power, did you check the actual outlet for power? You can use a voltmeter to test the available voltage at the bulb socket. You can also use an ohmmeter to test the resistance of the socket and make sure the socket itself has not failed. If this is the case, you will need to rewire a new bulb socket into place. If performing this at home, your main concern should be with making sure the new connections are protected from the environment. If you do not have the right amount of available voltage at the socket, you will want to trace from the fuses and relays to the socket every foot or so until you find where the voltage drop occurs. This is where your issue is and it must be corrected by whatever means necessary, which can only be determined once the issue was found. You may have a short or a damaged wire/connection along the way. If you would like to have this taken care of, a qualified professional, like one from YourMechanic, can come to your car’s location to diagnose the headlight problem and follow through with repairs.

Passenger seat heater not working properly.
ANSWER : Hello and thank you for contacting YourMechanic. The book says that you can use a 15, 20, 25, or 30 amp fuse. The power to the heaters are operated through the wiring to the main harness. There could have been a wire tied into it to make the seat work on the same circuit as the driver seat. This is common to find in the vehicles.

You can try putting a 15 amp fuse in the slot and see if the seat works. Try to avoid using a high amp fuse for if there is a problem with the heater you don’t want to burn it. If nothing seems to work, then the heater in the seat has failed and needs replaced.

If you need further assistance troubleshooting your vehicle, then seek out a technician, such as one from Your Mechanic, that can assist you with a seat inspection at your home or office. Best of luck.

Trouble with exterior lights – 2010 Mercury Milan
ANSWER : Hello, thanks for writing in. It sounds like you will need to replace both bulbs and all three fuses. The price of bulbs and fuses is so cheap most of the time, that the amount of time to test each component and inspect for errors, is usually not worth it. Driver safety and properly functioning headlights are very critical and we never recommend operating the vehicle at night without them 100% functional. Replacing all the fuses (and yes, absolutely replace #7) and bulbs should solve the issue. If the problem continues, you will want to start checking the power supply and then the switch. This can be done with a multi-meter. If you’d like to have this checked for you, a certified professional from YourMechanic can come to your home or office to diagnose your headlight issue and make the correct repair.

My headlights are not working correctly – 1996 Chevrolet Blazer
ANSWER : Hi there. Most of the time this is caused by a bad headlamp switch. When the switch fails, it will cause this to occur. If the switch is fine, then it may have an issue with the headlamp relay. I typically take my voltage meter and test the circuit starting at the headlamps until I find where the voltage is being lost.

If you want to have your headlamps fixed, consider having a certified mechanic, such as one from YourMechanic, come to your home or office to inspect the headlights and suggest any necessary repairs.