Parking brake warning light issue?

2000 MAZDA MPV
145,000 MILES • 1.6L • 6 CYL • 2WD • AUTOMATIC
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MING FENG
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I’m experiencing an issue with my vehicle listed above again. The parking light stays on even when the parking brake is disengaged. Previously, it would turn off automatically after driving for a while, but now it stays on continuously.

The parking brake lever is located between the front seats. I opened the panel, thinking I could replace the switch underneath. However, I discovered that the switch is very simple and unlikely to fail. I’ve included pictures and a video below for reference.

The switch has a wire with a spade terminal attached to it by a screw. From what I can tell, when the white button on the switch is pushed down, the spade terminal should not touch the metal bracket, breaking the circuit and turning the light off. Since the light remains on, it seems the problem isn’t with the switch itself but with something else along the wiring.

I’m unsure where to check next. Any advice would be greatly appreciated!
Jan 14, 2025 at 11:05 PM
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MING FENG
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More pictures.
Jan 14, 2025 at 11:05 PM
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MING FENG
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picture.
Jan 14, 2025 at 11:06 PM
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MING FENG
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video:
Jan 14, 2025 at 11:06 PM
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STRAILER
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Have you checked the brake fluid level? That uses the same warning light. Let me know. The switch looks okay, thanks for the video/image.
Jan 15, 2025 at 12:38 PM
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MING FENG
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hi, Ken, Thank you for always helping me. Yes I checked. The brake fluid is full.
Jan 15, 2025 at 1:00 PM
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STRAILER
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If you ground the wire does the warning light go out?
Jan 16, 2025 at 9:15 AM
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MING FENG
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No, the light is always on. Actually, the light should only turn on when the wire is grounded.

This is where I got confused initially. Previously, when it was working correctly, pulling up the parking brake lever grounded the wire because the wire would come into contact with the small U-bracket (which was mounted on the metal frame). This indicates there must be some logic behind the mechanism: the light should only turn on when the wire is grounded. For example, when the lever was pushed down, the wire hung freely, not touching anything around and therefore not grounded, causing the light to turn off.

There are no other wires in this area—only a single wire. It seems that the mechanism doesn't function as a traditional circuit. Instead, the light turns on or off depending on whether the wire is grounded.
Jan 16, 2025 at 7:31 PM
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STRAILER
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Yep, the light come son when grounded, lets unplug the brake fluid level sensor to see if the light goes out. Leave the brake light waring wire discounted for now. Here is the wiring diagrams on how the system works. Check out the images (below). Let us know what you find.
Jan 17, 2025 at 11:55 AM
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MING FENG
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Hi Ken, I’m not sure what you mean by “upload the brake fluid level sensor.” I located the sensor (see the attached picture), unplugged the wire, and noticed that the light turned off. I tested the continuity of the sensor, and it appears to be functioning properly. Does this mean the issue is not with the sensor, or could it still be the sensor’s problem even if the continuity test shows it’s good? Thank you so much!
Ming
Jan 17, 2025 at 7:16 PM
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MING FENG
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Hi Ken,
I wasn’t sure what to try next, so I sprayed electronic cleaner on the sensor and plugged it back in. To my surprise, the issue is gone. I also reinstalled the parking brake switch, and everything is now functioning properly. I’ll keep an eye on it to see if the problem returns. Thank you for your guidance!
Ming
Jan 17, 2025 at 8:29 PM
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STRAILER
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Glad you could get it fixed, thanks for letting us know. Please use 2CarPros anytime we are here to help.
Jan 18, 2025 at 10:29 AM