tail light going out when pressing break.?

Question

my tail light/brake light is faulting. When my lights are off my tail light works but when i press the brake it all goes out. Only on the left side. when my lights are on my blinker wont even turn on back their and still when i press the break the whole tail light goes out. I've paid mech. to fix it but it works for a lil while then stops. how can i fix this myself? any website to learn from or any sugestions

Answer 1

It would help to know the make and model of car you have, however, it appears you may have a bad "ground" or "common" connection on that fixture.

Bad electical connections are one of the automotive industries worst issues...hot, cold, vibrations, condensation, high humidity, corrosion, dirt, water, wear and tear and just plain age can cause connections to go bad.

Bad common connections to your chassis will sometimes allow tail lights to work due to their low wattage, but when you hit the brakes or use your turn signal, the added load will cause the ground current to over-exert the weak point which can severely limit the brightness of the lamps, making them appear to be out completely.

You can check your common connection with a voltmeter as follows: With your parking lights on, connect the positive lead of the meter to the common connection of your lamp fixture and the negative meter lead to your car's chassis, or better yet, your car's negative battery post (you will need an extra long wire if your battery is up front like most cars). The voltage should be near zero (less than 0.1 volts), then have someone press the brake, the voltage may rise slightly to around 0.1 or 0.2. In your case, the meter reading will be way up around 8 to 10 volts if you have a bad ground, if you read nothing it is possible there are other problems with the fixture or electrical system. It cannot be a short as this would blow the fuse, so the ground or common must be giving away when higher electrical currents are demanded.

Have you ever had a trailer hitch installed with electrical connections to the trailer? If so, sometimes the splices can interrupt the functions of these lamps due to breakdown of the splice or corrosion of any exposed conductors, but my guess at this point is that your grounding connection is bad.

Answer 2

The mechanic is just wiggling wires. You have a bad ground connection or socket that needs to be chased down. It's just a matter of taking the tai llight fixture apart and looking at the wires and connections.

Answer 3

The electronic board in the tail light housing is bad.