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Brake lights turn on parking lights

My daughter has a Mazda 323 with 240,000 miles. I noticed that when she put the brakes on the parking lights come on. Also when she puts her lights on at night the brake lights stay on. She also said her emergency brake indicator light stays on. I checked for taillight corrosion, because we’ve had water in the lense, but everything looked clean. I don’t know if I have a short, a bad relay or a bad ground. Has anyone had this problem? Thanks

Well if tailights stay on for a bit after you depress the brake pedal that usually just means a sticking brake light switch down where your pedals are. Emergency brake is probably pretty corroded or rusty at this point as well, so that could be hanging a bit giving you a light. I’m not a Mazda expert, but these are places I’d look first.

I haven’t checked but if your Mazda has dual element parking / brake light bulbs, make sure they are inserted correctly.

The pins on the metal bulb body are staggered, it’s difficult (but not impossible) to partially install them backwards, this can cause a short between the parking / brake light circuits exactly as you describe.

There is probably a ground problem for the brake light/tail light circuits. There is power back feeding into the light circuit looking for ground.

Check the grounds at the light assemblies.

If the car has combined lamps (same bulb for parking and brake) I would start there and replace the two bulbs. It is possible for the filament to sag and make contact with the second filament, which would account for what is being observed.

My second guess willey suggested. A grounding problem.

Everyone seems to have a similar idea – the rear light assemblies. I agree, and check for corrosion in the lamp sockets.

Check the grounds as well as the wiring at the taillights. I’m guessing that one of the wires has rubbed against the frame/body and created a short, so that current for the taillights goes other places it’s not supposed to.

Had this same thing happen on a truck (brakes not only turned on the parking lights, but the instrument cluster lights too!), it turned out that loose hanging wires from the trailer harness had rubbed on and grounded out against the frame. Cleaned up, taped up, secured away, problem solved.

I vote for a broken ground at the tail lights. The bulbs will want to ground, and will back-feed through the parking light circuit through the common (broken) ground to the front parking lights that are still grounded.

You all were really great helping me trouble shoot my problem. I was going through the bulbs cleaning off the corrosion, when the last one I pulled out turned out to be a single element bulb inserted into a double element socket which caused the short causing my problem. I am so happy now that she has properly functioning brake lights. Thanks so much.