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I had the unfortunate experience of leaving my car parked in D gear with the emergency brake (aka hand brake) off. It rolled downhill and sustained some damage. Seems like the mechanism to stop me from getting the key out unless I'm in "Park" is broken.

I'd like to set my car (a 2006 Mazda 3) up with some sort of a warning system. Something similar to having a buzzer sound if the emergency brake is off and the driver door is open.

I've not been able to find such kits online to be purchased. Am I using the wrong search terms? Might anyone be able to point me in the right direction? Instructions for a DIY project would also be most welcome.

urig
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Well, the thing is, you already have this two different ways in the car.

  1. If the transmission is not in Park or Neutral, the ignition should not release the key.
  2. If you open the door and the key is still in the ignition, there's a beep or a buzzer that will let you know.
  3. The hand brake, when applied, turns on a red light on your instrument panel.

How did you get the key out of the ignition with the transmission in D?

tlhIngan
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Why not use a small 12v buzzer, relay and a push type switch (push to close) fitted to the handbrake so that if the door is open the buzzer sounds : just have the relay "earth" through the door switch - may need a diode though (otherwise the relay could earth through the interior light). Another solution fit a second door switch...

Solar Mike
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You're looking for two switches/circuits.

  • The "door is open" circuit, which closes/energizes when a front door is open. The main purpose of this circuit is to light the dome light.

  • The "Park/neutral safety switch" which (hopefully) opens when the car is in park or neutral. This is normally an interlock with the starter motor to keep you from cranking the engine in drive. You may get lucky and also find a "Park safety switch".

If you're very lucky, the park/neutral switch operates by grounding out its single wire. Also look for extra unused contacts on the park/neutral switch. The goal is to find a switch which grounds out *when the car is NOT in park.

You are more likely to find a "ground if parking brake on" switch on the parking brake. Check its action: if it has unused contacts, you may find it has a "ground if parking brake off" mode.

If all else fails, get a limit switch and mount it appropriately. It will also work to use a magnetic reed switch and glue a neo magnet to the correct location so the reed switch opens in Park.

This makes it a simple matter of a diode and a buzzer of choice. The diode is to prevent unwanted backfeeding.

When you open the door, the "open door" circuit is energized. Current flows from this source, through your diode, through your buzzer, through the not-in-park switch if closed, to ground.

Harper - Reinstate Monica
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I'm working on an electronic alarm that will sound if the parking brake is left on when the vehicle is put in gear. It will also sound if the vehicle is taken out of gear (put in park or neutral) with the parking brake off. I've built a prototype of this all electronic alarm kit and successfully installed it on my motorhome. I hope to put it on eBay soon as a marketing test. It should cover your needs nicely, and then some.

Jeffrey Stromquist
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