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Discussion Starter · #1 ·
I finally got around to building my circuit that disables Stop/Start upon startup. It seems to work! - in the garage - I've yet to try it on the road.
Here's a video of it lighting the disable light 5 seconds after startup. The button is still usable to reactivate the Stop/Start if desired. No DTCs are displayed (just low gas).

Here are some details for the techie folks...

I've included a picture of the circuit diagram and the circuit itself.
The circuit is basically one of these connected to a SPST relay which connects to both pin 8 and pin 10 of the headlamp switch module through separate resistors. When the relay is active, it connects the pins to ground through their respective resistor.
Each pin has a separate non-pressed and pressed resistance. I guess this is to help the Body Control Module detect open connections or shorts. The values of the resistors used in this circuit are calculated to match the normal button press value when run in parallel with the non-button press value.

The timer has to be programmed through a procedure to make the appropriate pulse after 5 seconds. I used timer function 7 with a t1 of 6 seconds and t2 of 1 second. Once programmed, it retains the function indefinitely.

I used these which match the diameter of the wiring harness wires. They allow easy removal of the circuit if needed. This is the I used. This has the two values needed - 1900ohms (I used 2K) and 675 ohms.

Installing it is a little tricky. The headlamp switch module prys out. There are four spring loaded clips in the upper right, upper left, lower right and lower left. You have to gently alternate prying on these four spots little by little. Don't pull on the chrome ring around the knob - it comes off easily. This reveals the connector which can be unplugged to install the t-connectors to the appropriate wires. The diagram is from the perspective of looking at the connector from the back side where the wires come out. I pushed the relay and timer through the opening in the dash frame zip-tied it to keep it from rattling.

If anybody else wants to try this I'd be happy to answer questions. It does require some soldering skills and some basic electronics knowledge would be helpful. Testing on the bench should be done before install.
 

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Great work!!!

I think the different resistance is the way the CAN bus works. But you already sorted that out!!!

Thank you for sharing this. I’m not very good at soldering so for now I’m going to press the button when I remember to, until I get brave to try.
 

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I finally got around to building my circuit that disables Stop/Start upon startup. It seems to work! - in the garage - I've yet to try it on the road.
......
If anybody else wants to try this I'd be happy to answer questions. It does require some soldering skills and some basic electronics knowledge would be helpful. Testing on the bench should be done before install.
Good idea, well done :cool:. I did something similar in the past for the ASR switch on my 147 GTA, if I get round to it I can probably just use/adapt it for the start/stop ;)
taking the start/stop button/panel out is what held me back till now ;) (and hoping that disabling it via OBD would be available short-term)

just as an example, see:
http://home.planet.nl/~jwq/temp_gta/asr_switch_instructions.pdf
 

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As a Retired Broadcast Engineer I tip my hat and bow to you and say THANKS, MANY THANKS.

I thought about using a delay timer, but have been to lazy to to do it.
Rich
 

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Great work! By any chance, when you had the light switch out, did you see a way to remove the spring back from the lights off position? I hate it that I can't turn off my lights for good.
 

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Discussion Starter · #8 ·
Great work! By any chance, when you had the light switch out, did you see a way to remove the spring back from the lights off position? I hate it that I can't turn off my lights for good.
No, I didn’t check that. I didn’t even know that it does that.
 

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No, I didn’t check that. I didn’t even know that it does that.
I think he’s referring to the auto headlight position default. If you turn the knob counterclockwise it will turn off the lights/auto headlights, but it springs back to the auto position, so next time you start it’s back to auto mode.
 

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Brilliant effort. I'm content simply pressing the button when I don't want start/stop.
 

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Discussion Starter · #11 ·
Good idea, well done :cool:. I did something similar in the past for the ASR switch on my 147 GTA, if I get round to it I can probably just use/adapt it for the start/stop ;)
taking the start/stop button/panel out is what held me back till now ;) (and hoping that disabling it via OBD would be available short-term)

just as an example, see:
http://home.planet.nl/~jwq/temp_gta/asr_switch_instructions.pdf
Nice package! Is that something that you produce and sell?
 

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You found a niche product

I watched your video. Bravo! You should build a business around this product. Especially, if most manufacturers accomplish this with similar CAN bus technology. There are plenty of MB E-Class owners that would appreciate this device. Choose a similar vehicle, one where the manufacturer will literally produce over 1-million examples over the model production run. You could probably rent an example from a major fleet, for a few days, to R&D the product.
 

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Discussion Starter · #13 ·
Good news is that the module works on the road. The Auto start stop is disabled after a normal in-car start.

Bad news is that remote start is unhappy. Apparently it doesn't like someone being in the car an pressing the S/S disable button when it's under the remote start procedure. As soon as the timer kicks in, the car shuts off. These cars are too smart!
 
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Good news is that the module works on the road. The Auto start stop is disabled after a normal in-car start.

Bad news is that remote start is unhappy. Apparently it doesn't like someone being in the car an pressing the S/S disable button when it's under the remote start procedure. As soon as the timer kicks in, the car shuts off. These cars are too smart!
How about increasing the timer to 8-10 minutes.
Most people should be in the car by then. And, the car does not auto stop while the engine is still cold.
 

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Discussion Starter · #16 ·
How about increasing the timer to 8-10 minutes.
Most people should be in the car by then. And, the car does not auto stop while the engine is still cold.
Not a bad idea. Except when you make a stop to buy gas or run in the store and then you re-start, the S/S would be active again until the 10 minute timer popped.
 

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Nice package! Is that something that you produce and sell?
A couple, just as a hobby via fora due to demand whilst I still had my GTA. Traded my GTA in for the giulia.
Basically I think it's very similar to your project, just uses a microcomputer chip with custom program to take care of the timing function, and miniature relay, custom PCB ;)
 

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I only have less than 1k miles on my 2017 Giulia (sport). I observed that some day the auto s/s works some day not. There are more days it is not working than it do.
Question: is this function activated depending on outside temp, engine or any other conditions? if it is not working (not shut the engine) is it a malfunction ( a welcomed one) or just has its own logic (mind)?


Thanks.
 

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Question: is this function activated depending on outside temp, engine or any other conditions? if it is not working (not shut the engine) is it a malfunction ( a welcomed one) or just has its own logic (mind)?
Page 47 of your owner's manual shows what conditions can cause the Stop/Start system to deactivate:

"Stop/Start will deactivate in the following scenarios:
- The climate control system is in AUTO mode (indicator illuminated), and the vehicle has yet to reach the set temperature
- The climate control system is in LO maximum cooling
- The climate control system is in HI maximum heating
- The climate control system is in the MAX-DEF status

When the Stop/Start system is active, the engine will restart if the inside temperature changes significantly, or if the LO setting, or MAX-DEF setting, is activated."
 

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I live at 6500 feet, Lake Tahoe, and my Start/Stop never functions at this altitude. The algorithm that analyzes the air mix apparently decided their is insufficient oxygen at this altitude. I soon as I drive down to the Carson Valley it begins to function again. FWIW
 
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