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Device to automatically press brake hold button at startup
Hey, this seems pretty simple for someone with basic electronics knowledge -- does anyone know how to implement a device that will press the brake hold button in order to activate it whenever the vehicle is started?
Essentially the brake hold button has to be pressed to activate every time the vehicle is started (and doesn't remain on at next startup even if it was previously shut down with the brake hold on).
Such a device would simply need to connect the two wires that pressing that button would connect whenever power is first detected to it at startup. Seems like a relay of some sort would work.
Anyone know how this can be done?
I don't have the wiring diagrams on the RX350 to verify that the Brake Hold actuator button is a simple momentary contact switch with a two wire plug but if it was, something like this could be used to do it :
It's a $5 item from eBay. Using P4 would work. You could turn it on with a +12V source that comes on with vehicle Ignition, set a 5 second ( or so ) delay, have the onboard relay come on to "make the Brake Hold" button press by connecting the two switch wires and then turn the relay off after 3 seconds. These times are adjustable in case you wanted a longer/shorter delay to get the car started/initialized and/or needed a longer/shorter Brake Hold button press. It wouldn't draw any power while the engine was off, so no dead batteries after a 3 week idle period.
The only gotcha would be this note from the owners manual :
The initial delay could be set longer to give you time to fasten your seat belt prior to "pressing the button".
Last edited by FlopTop04; Feb 16, 2020 at 10:21 AM.
I like break hold a lot and use it every time I drive. It is incredibly annoying to have to turn it on but I just live with it, remembering to activate a few buttons like automatic cruise control, brake hold, heated steering wheel as soon as I get into the car.
Hey, this seems pretty simple for someone with basic electronics knowledge -- does anyone know how to implement a device that will press the brake hold button in order to activate it whenever the vehicle is started?
Essentially the brake hold button has to be pressed to activate every time the vehicle is started (and doesn't remain on at next startup even if it was previously shut down with the brake hold on).
Such a device would simply need to connect the two wires that pressing that button would connect whenever power is first detected to it at startup. Seems like a relay of some sort would work.
Anyone know how this can be done?
Search for messages regarding disabling auto stop-start (obviously dealing with other cars). Everybody wants something that will automatically "press" the button that disables auto stop-start. There are actually commercial products that do that for certain cars (e.g, autostopeliminator.com).
Adapting something like this for your purpose is unlikely to be trivial...
In my current NX and my soon to be RX the parking brake can be set to automatic. The following is from the 2020 manual. Depending on your year it might be slightly different.
I don't have the wiring diagrams on the RX350 to verify that the Brake Hold actuator button is a simple momentary contact switch with a two wire plug but if it was, something like this could be used to do it :
It's a $5 item from eBay. Using P4 would work. You could turn it on with a +12V source that comes on with vehicle Ignition, set a 5 second ( or so ) delay, have the onboard relay come on to "make the Brake Hold" button press by connecting the two switch wires and then turn the relay off after 3 seconds. These times are adjustable in case you wanted a longer/shorted delay to get the car started/initialized and/or needed a longer/shorter Brake Hold button press. It wouldn't draw any power while the engine was off, so no dead batteries after a 3 week idle period.
The only gotcha would be this note from the owners manual :
The initial delay could be set longer to give you time to fasten your seat belt prior to "pressing the button".
In my current NX and my soon to be RX the parking brake can be set to automatic. The following is from the 2020 manual. Depending on your year it might be slightly different.
that is not the same as brake hold.
brake hold works at stop lights, things like that. it takes over holding the pedal once you come to a stop.
so if enabled, and you come to a red light, once the car stops, you can take your foot of the brake pedal.
There are already settings to have the parking brake set to automatic, so when you turn on the car the brake is on. It turns on when in park and off when out of park. Why fix what is working???
There are already settings to have the parking brake set to automatic, so when you turn on the car the brake is on. It turns on when in park and off when out of park. Why fix what is working???
The brake hold is nothing more than an electronic version of the mechanical parking brake. If you follow the instructions in the manual the brake will be applied every time the car is started (yes you must put your foot on the brake pedal to start the car) and if set properly it will come on every time you put it in Park and every incline that is steep enough for the engine RPM's to keep the car from rolling back.
Word of caution regards the "Automatic Parking Brake" feature, when turned"on". If you stop the Rx while in traffic and disconnect seat belt for some reason (such as to get $$ out of your pocket), the RX with Auto Parking Brake set to "ON", the car will default to turn the parking brake "ON". The car is still in gear; however the Parking Brake is on and there is a message on the Speedometer Cluster that sez to deactivate the Parking Brake, turn it "OFF" using the Parking Brake button mounted just in front of the gear shift. That can be a pain when sitting in traffic and trying to get the Rx to move and find the correct button to release the "Parking Brake" that has been turned on automatically. Be aware of where the Automatic Parking Button is located so you can turn it off quickly. pushing on the "Brake Hold" button is no help
Device to automatically press brake hold button at startup
