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I have no signal in brake light system. The bulb and the fuse of the brake are both fine, but when i step on the pedal brake, there's no light in it...What seems to be the problem? How can i fix it? Thank you very much.
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Buy a cheap test light to run simple tests to see where power is being lost. Start at the brake light fuse. Clip the ground lead of tester to a metal bracket or bolt under the dash. Then use the tester's probe to touch the little indents on top of the fuse. There are two indents on each side of tops of fuses-these are test ports to check if a fuse has blown. The brake light fuse will be "hot at all times", so touching the metal strip inside the indent should light up the test light. If not, check if your ground clip is good: turn the key to on. Now every fuse in the dash panel should be powered. Every fuse should light up the tester. If both indents on a fuse light up the test light, that means it is a good fuse. If only one side lights up the tester, that is a blown fuse. Now back to the brake light fuse, key off. Does it show power? If not, maybe a fuse link off the battery that distributes power to the fuse panel has burned out. If fuse shows power at both ends, move tester to the brake light switch and check for power at the switch-this wire to brake switch is again "hot at all times". Should have power in, and when brake pedal is depressed switch should also have power out. From the brake switch, the brake signal wire goes up into the turn signal switch, and is then routed out to the brake lights. With pedal depressed, you can check for power in and power out at the turn signal connector. Don't pull the connector apart, but back probe the connector with the test light probe. You know the color of the brake light wire from brake switch to the turn connector, so easy to check for power in. Power out should be on two wires, one for each side of the rear lights. If the turn signal switch has power in but no power out, with brake pedal depressed, probably a defective turn switch. Post back with results, or when you find the problem. Good luck.
Check System Fuse - A fuse is used to protect the brake light circuit from amperage overload. If the fuse has failed it will not allow the electrical current to continue to the brake lights. To check the fuse, first locate the brake light system fuse in the fuse panel which is either under the dash or under the hood in the power distribution center. Connect the test light to a ground like an engine or dash bracket and turn the ignition key to the "on" position. Using the test light probe both sides of the fuse. If the test light illuminates on both sides the fuse is okay continue onto the next step. If one side of the fuse illuminates the fuse has failed and needs to be replaced. If the fuse fails as soon as it is replaced or when you apply the brake pedal the brake light electrical circuit is shorted to ground. Rarely a system short can occur, a car repair manual is needed to find the wiring schematic for the brake light circuit. Once the brake light wiring has been located inspect and repair as needed.
Check Brake Light Bulbs - All cars have three brake light bulbs that create the brake light illumination affect. If all of these brake light bulbs fail no brake light operation will occur. I know what you're thinking, you might say all three brake lights at once? But in reality one brake light went out at a time and you did not notice. People only tend to notice something when they almost run into the back of your car to help persuade them to inform you the brake lights aren't working. Remove any of the brake light bulbs to confirm the bulb is okay or burned. After the bulb has been removed inspect the filament and replace if failed. If the brake light bulbs are okay continue to the next step.
Checking the Brake Light Switch - A control switch is used to connect the brake light electrical circuit. This switch is located near the brake pedal lever. Basic switches have just two wires, power in and power out to the turn signal switch. Use a test light that is grounded and with the key in the "on" position test for power at one side (wire) of the switch, then press the brake pedal while testing the opposite side (wire). It should illuminate the test light, if electrical power is connected through the switch go to the next step. If no power is detected through the switch the brake light switch has failed and replacement is required. If your car is equipped with more than two wires integrated into the brake light switch a car repair manual is needed to locate the proper brake light circuit wiring.
The third or High Mounted Brake Light runs straight off the brake light switch on the brake pedal arm. You say you tested the "brake unit"? I assume you mean the third brake light assembly, and if you get power there when someone steps on the brake pedal, then the bulbs are bad.
The power flow for the brake lights goes like this: Fuse ->Brake switch -> Turn signal switch -> Rear lights. The only difference is, if you have a 3rd brake light in your rear window, that gets its power directly from the brake switch. It does not go thru the signal switch first. So, if you are having a brake light problem, and your fuses are good, check the 3rd light in the rear window, if it lights up (assuming the bulbs are good, no one ever changes them), then the problem is most likely in the turn signal switch, hope this helps!
If you activate the turn signal switch and you step on the brake pedal, the turn switch (on the steering column) deactivates the brake light to make the signal light more visible. The bulb for the stop and turn lights is the same.
Turn hazard lights ON. If they don't blink, replace turn/hazard flasher, If one or more lights don't come on, replace bulb.
Check fuse and circuit wiring for broken or loose connections. If all looks fine, check following:
If front turn lights work fine, check brake/turn bulbs.
If turn lights come on but don't blink, replace turn signal/hazard flasher.
If front and back turn lights don't come on, replace switch on column.
If the fuses and bulbs are good, chances are, it's the brake light switch/relay. It's under the dash up against the brake pedal arm. That's what sends the signal to the brake lights when you step on the brake pedal. It's a cheap part and easy to replace. You can get it at any of your local auto parts stores.
Did you check for voltage at the light socket before replacing the fuse?
Was the fuse blown? If so, you need to find out why it blew. (fuses do not blow for no reason) If not, why did you replace it?
Did you check for voltage in and out of the brake switch? Brake switch failures are common on Dodge trucks. There should be voltage going in, but none coming out the other side until the brake pedal is depressed. If there is voltage going in, the fuse is not blown. If there is still no voltage on the other side when the brake pedal is depressed, then the brake switch is your problem-child.
The next step is to check for voltage in and out of the multifunction switch. (turn signal switch) The brake lamp voltage is switched on and off by the turn signal switch. Failure of the turn signal switch can cause a "no brake light" symptom. This is a common failure among most makes of vehicles. This failure can often be verified by stepping on the brake pedal and wiggling the turn signal switch. If the brake lights flicker on and off while doing this, the mutifunction switch needs to be replaced.
Troubleshooting Procedures - Read Completely Before Beginning (American Car) All Brake Lights Not Working
Check System Fuse: A fuse is used to protect the brake light circuit from amperage overload. If the fuse has failed it will not allow the electrical current to continue to the brake lights. To check the fuse, first locate the brake light system fuse in the fuse panel which is either under the dash or under the hood in the power distribution center. Connect the test light to a ground like an engine or dash bracket and turn the ignition key to the "on" position. Using the test light probe both sides of the fuse. If the test light illuminates on both sides the fuse is ok continue onto the next step. If one side of the fuse illuminates the fuse has failed and needs to be replaced. If the fuse fails as soon as it is replaced or when you apply the brake pedal the brake light electrical circuit is shorted to ground. Rarely a system short can occur, a car repair manual is needed to find the wiring schematic for the brake light circuit. Once the brake light wiring has been located inspect and repair as needed.
Check Brake Light Bulbs: All cars have three brake light bulbs that create the brake light illumination affect. If all of these brake light bulbs fail no brake light operation will occur. I know what you're thinking, you might say all three brake lights at once? But in reality one brake light went out at a time and you did not notice. People only tend to notice something when they almost run into the back of your car to help persuade them to inform you the brake lights aren't working. Remove any of the brake light bulbs to confirm the bulb is ok or burned. After the bulb has been removed inspect the filament and replace if failed. If the brake light bulbs are ok continue to the next step.
Checking the Brake Light Switch: A control switch is used to connect the brake light electrical circuit. This switch is located near the brake pedal lever. Basic switches have just two wires, power in and power out to the turn signal switch. Use a test light that is grounded and with the key in the "on" position test for power at one side (wire) of the switch, then press the brake pedal while testing the opposite side (wire). It should illuminate the test light, if electrical power is connected through the switch go to the next step. If no power is detected through the switch the brake light switch has failed and replacement is required. If your car is equipped with more than two wires integrated into the brake light switch a car repair manual is needed to locate the proper brake light circuit wiring.
check the fuse for the brake lights. The brake lights and siganl lights use the same bulb filament. The parking and running lights use a dimmer filament in the bulb. There are 2 filaments.
Your brake lights work through the multifunction switch which operates the signal lights. If the signal lights work, you may have a bad brake lamp switch which is on your brake pedal arm.
Let us know what you find.
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