Prius Auto Lock Module Design - Will My Redesign Work?

Thread Starter

120m256

Joined Jun 11, 2021
2
I would like to add auto locking to my Prius. There is an established design that locks the door when both the start button and brakes are pressed (turning on the car). I found a single relay board on Amazon that appears to eliminate the needs for the second relay in the established design. I believe it does this because the trigger is separated from the relay power. Please let me know if my solution would work, and if not, what would I need to change. Thanks for any help.
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MisterBill2

Joined Jan 23, 2018
9,851
You will find that autolock scheme to be a serious nuisance when you just need to move the car a bit. And the circuit shown activates whenever accessory power is active. The much better system locks the doors with a momentary pulse when the car reaches a speed of about 15MPH.
There is another concern, which is that in the event of a relay board malfunction, that door lock command may stay active until the door lock motors overheat and catch fire, with you stuck inside because they are locking the locks. So you would be stuck inside the burning car. Not a fun time at all.
Your other problem is that it will lock the doors when you push that button a second time to switch the engine off.

Having one button to both start and stop the engine is among the very dumbest thing that could have been done in the last 50 years. If there is a mechanical problem and the throttle is stuck open the system will not let youswitch off the engine until the car stops, and so you will be stuck going 80MPH and no way to shut down the engine. That button only sends a request to the computer, which believes that it is much smarter than you are.
 

MisterBill2

Joined Jan 23, 2018
9,851
The key lock on a good vehicle allows a forced engine shutdown no matter what. On every safe vehicle switching off the ignition stops both the spark and the fuel pump, so a runaway can be stopped.
The push button DOES NOT switch off the power! The button sends a request to the controller and the controller may not switch off, because it thinks that the engine must stay on for the power steering. THAT IS A HUGE DIFFERENCE from having a key switch that will shut down the engine by switching off the power.
There may possibly have been a change but I doubt it.
 

shortbus

Joined Sep 30, 2009
8,966
The push button DOES NOT switch off the power! The button sends a request to the controller and the controller may not switch off, because it thinks that the engine must stay on for the power steering. THAT IS A HUGE DIFFERENCE from having a key switch that will shut down the engine by switching off the power.
There may possibly have been a change but I doubt it.

Don't know what kind of car you are driving that does that. And since most everything in a car now days is electric, even power steering, you are so far behind the times. He is asking about a Prius after all, no engine driven power steering pump there.
 

MisterBill2

Joined Jan 23, 2018
9,851
ELECTRIC DRIVE VEHICLES are an interesting case. And the kind of vehicle that I drive does have an ignition switch that does cut off engine ignition power as well as fuel pump power. But I am asking youto stop the attack mode, it does not belong in this venue.
 

shortbus

Joined Sep 30, 2009
8,966
ELECTRIC DRIVE VEHICLES are an interesting case. And the kind of vehicle that I drive does have an ignition switch that does cut off engine ignition power as well as fuel pump power
You do know that most every new car has electric power steering don't you? The emergency brake is now electric, some power brakes are too. My 2018 Equinox did, the new Encore I just leased does. Even since around 2010 or so the throttle is drive by wire, no cable. And if your car has a ECM it is controlled by it not the key its self. When you turn the key it tells the ECM to shut down, it doesn't run through the key switch like the old days, it works just like the push button start does.
 

Thread Starter

120m256

Joined Jun 11, 2021
2
@MisterBill2 motorcycles and some race cars use a toggle on/off switch, with a separate momentary switch for the starter. I agree, better design, but too complicated for most car drivers.

The Prius gen2 mechanically unlocks the door when you pull the inside lever. No chance of this getting stuck if you need to get out in an emergency.

I know my design may activate the locks when shutting down the car. The prius is somewhat unique in the way the gear selector works. You don't have to put the car in park when shutting down, it does this automatically when you hit the start/stop button to turn the car off.

So does anyone see any issues with my design other than activating the power locks on shutdown?
 
@MisterBill2 motorcycles and some race cars use a toggle on/off switch, with a separate momentary switch for the starter. I agree, better design, but too complicated for most car drivers.
I had to put a push-button start on a 1987 Plymouth Caravelle when it was a nucence to use a pair of plyers to tun the ignition switch. She had arthritis and it was just too much effort and amount of motion to turn the key on the column.
 
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