![]() ![]() If it did not, the lights would stay on and not flash. When we use the turn signal switch, it cancels the brake light signal, on the side selected. On this type system, the turn signals and brakes use the same circuit. With a bad turn-signal switch, the third-light should still function. On vehicles that use the same lights for brakes and turn signals, a bad turn-signal switch can cause the lower brake-lights not to work. If the flashers work, check for blown fuses as a few vehicles use separate circuits for the lower and third brake lights. Again try the emergency-flashers to check for wiring, socket and lamp problems. When the lower lights do not come on and only the third-brake light works, the brake-light switch may be ruled out. ![]() If the switch does not show continuity when pressed, replace the switch. Test the switch, as described above, except there should be continuity when the switch activated. Good fuses mean the most likely cause is the brake-light switch. The owner's manual or service data will show fuse box location. Check for a blown fuse and be careful, as many vehicles have more than one fuse box. If all lights come on, when the emergency flashers are turned on, this shows the bulbs, wires and sockets are good. The emergency flashers often use the same wiring, bulbs and sockets as the brakes. On vehicles where the flashers are separate from the brake lights, this will not apply. A quick test is to try the emergency-flashers, on vehicles that use the brake lights as flashers. If it too is not working, the brake-light switch, a bad fuse or an unplugged harness is likely. When the brake lights will not come on, the first thing to check is the third-brake light. Finding such a shorted-circuit, is best left to a professional. Unplug the brake-light switch and if the lights stay on, a short circuit is the case. The final possibility is a wire shorted to power. Pull up on the brake pedal and if the lights go out, switch mis-alignment or pedal position error is the likely cause. In rare instances, the brake booster may fail, and the pedal will not rise enough to contact the switch. If the plunger of the switch does not contact the pedal, check for an adjustment. Pressing the pedal should cause the switch to move. With the pedal released, the brake-light switch should be pushed to its full off position. Honda, Toyota and many other vehicles use these rubber pads and have this problem.Ī switch may also slip out of position, increasing the space between the plunger and the pedal. If these pads break or fall out, the pedal may not push the switch enough when released. Many vehicles have small plastic pads, where the switch contacts the pedal, when released. The brake pedal may also fail to contact the switch. These are sometimes used by the cruise control, transmission and other systems. Other terminals may operate in a different manner. If continuity is indicated when released, or open-circuit shows when depressed, replace the switch. In this position, the brake light switch changes to an open-circuit. When we release the brake pedal, it returns to the up-position. The brake-lamp portion of the switch will show continuity when the brake pedal is depressed. Using the wiring diagram, we can determine which leads should have continuity and when. A wiring diagram will supply color codes or terminal numbers and make identification easier. Some vehicles may have multiple switches on the brake pedal, and some switches may have more than one set of contacts. With only two terminals, continuity should show in one position and an open circuit in the other. The wiring diagram shows which terminals to check. To test an analog brake-light switch for staying on, remove the switch and test for continuity between the terminals. A wiring diagram and ohmmeter are needed. Service data for the vehicle in question will normally identify the type. These are far more difficult and may require professional service. Some modern vehicles may use digital sensors instead of a switch. Analog switches are very straight forward. Before replacing a switch check to see if it can be tested. If the contacts stick, the switch may continue supplying power to the lights, though it is released. One of the more common is a bad brake-light switch. Only a few things normally account for brake lights staying on. Please read, " Tips on Automotive Electrical Testing," for more information. Pushing the probe into a light socket will spread the contacts and cause the socket to fail. The point of the tool probe should only touch the contact, when checking. Using these tools properly is very important. When they do, this guide can help find the problem.Ī volt ohm meter or a LED test light will be needed for some tests. Press the brake pedal and they come on, release, and they go off. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |