DIY Engine Start/Stop workaround

[dwightlooi]

Background

Many cars now come equipped with Start/Stop. Many consumers hate having their engines turn off automatically at a stop light and coming back on when they release the brake pedal. They hate it because it reduces the life of the starter, degrades the battery, may increase wear on the engine and REDUCES REFINEMENT of their vehicles -- having the motor shudder to a stop and shuddering to life repeatedly is decidedly less refined than a smooth imperceptible idle. They hate it because it saves an imperceptible amount of fuel in most driving conditions.

Most manufacturers equip cars with a Start/Stop disable button (except in atrocious cases like the 2017 Terrain which doesn't even have one). But, in order to have very slightly better EPA MPG numbers, they usually make the buttons "non-latching". That is, you can manually turn Start/Stop OFF but every time you start the car it reverts to ON. They do this so that the vehicle's MPG and CAFE numbers are calculated with Start/Stop ON. Had the button been "latching", it'll be calculated as the average between when it is OFF and when it is ON. Myopically, manufacturers almost universally choose very marginally better EPA fuel economy ratings (~0.1 mpg), and kissing up to environmental extremists in government, over customer satisfaction.

Solution

There are several commercial aftermarket solutions to defeat Start/Stop. But, for people who want to do it yourself, here's a solution which turns start stop off every time you start the car. This solution works with ANY car with a start/stop button, and it fully retains the functionality of the start stop button.

(1) First, you need to go buy yourself a timer relay. It'll cost you about $17 and you can get one here (not affiliated to me but it's a product that works):-

https://www.amazon.com/Timer-Delay-Relay-Hours-Cycling/dp/B00PD65UGA

(2) Secondly, you need to find the wires that go to the START/STOP button. It'll be the wires that shows a closed circuit when you push the switch (and only when you push the switch).

(3) Find your fuse box. There should be a terminal which is ON (only) when the car is running and OFF when the car is not running. Find it, and use that to power your Timer Relay so that it gets power (only) when the car has been started; it doesn't get power when the car is off.

(4) Read the instruction manual and program your Timer Relay.

• Mode#7 -- Delayed Interval (Single Cycle) -- if you are using the relay I linked to
• DELAY (t1) 3 sec
• INTERVAL (t2) 1 sec

(5) Wire your Timer Relay to where your Start/Stop Switch harness plugs into the vehicle's electrical system or splice into the switch's wires -- it makes no difference functionally.

Once you have done the above the following will happen every time you start the car:-

• Timer Relay receives power
• Timer Relay waits 3 secs (t1)
• Timer Relay presses the Start/Stop Button for you and holds it for 1 sec(t2)
• Timer Relay releases the Start/Stop button
• Timer Relay does nothing for the remainder of the duration the car is running.

Basically, the Start/Stop Button is getting pressed and released automatically 3 secs after you start the car, turning start/stop off. If you want to use start/stop, you can hit the button to turn it back on. The button continues to work to turn start/stop off or on as much as you like; the relay simply presses it once every time you start the car so you don't have to. Viola!

Edited February 7, 2019 by dwightlooi

[A Horse With No Name]

Thanks for this....!

[Suaviloquent]

Freakin awesome!

[daves87rs]

I like this...