Does anybody know if you can disable the stop start function on a fiat 500 (2007+) without getting the orange warning light in the cluster using MES? Now I push the button on the dash every time I start the car. Best option would be that the function works the other way around so that when I press the button stop start is activated.
500 Disable stop start
- Thread starter dagdromer
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500 Disable stop start
Piccolo Nero e Bella
Prominent member
My orange light has been glowing merrily for years - I just don't 'see' it any more. I don't know when they changed it but my switch turns off S/S and it stays off permanently unless I push the button again.
If the car, as built, has a switch to turn it off (or the software equivalent via a menu), then it won't be illegal. Manufacturers won't provide the ability to turn anything off if doing so would make the car unroadworthy in the market for which it's being sold.
DRL's are a good example of this. There was a cutoff date after which new cars could not legally be sold without DRL's (the precise date depending on whether or not it was a completely new design). 500's sold before that date have the ability to turn DRL's off in the menu. Those that were sold after the cutoff had the option to switch them off in the menu removed.
If you have the ability to turn your DRL's off using the car's menu controls, then doing so is legal. Hacking the software via the OBD port to disable them on cars produced after the cutoff isn't.
Understand your irritation with the system as i also find the dash light obtrusive and distracting!
however if like the vast majority of 500 owners out there your system hardly ever works anyway 
then just leave it turned on and as its not working the light won t come up and theres no need to press the manual switch to turn it off if its non functional! ( unless your one of the 5% or so of owners where its actually functioning properly!!!) in which case just ignore me!
however if like the vast majority of 500 owners out there your system hardly ever works anyway then just leave it turned on and as its not working the light won t come up and theres no need to press the manual switch to turn it off if its non functional! ( unless your one of the 5% or so of owners where its actually functioning properly!!!) in which case just ignore me!
Piccolo Nero e Bella
Prominent member
Presumably a car with non-functioning DRL's would not pass its MOT, but what about a car with non-functioning S/S?
Piccolo Nero e Bella
Prominent member
As one of the 5% I shall ignore you thenUnderstand your irritation with the system as i also find the dash light obtrusive and distracting!
- but I still leave it switched off and ignore the yellow light as well...
I'm one of the 5% as well. Even with the current cold weather it is working great. So good it even tries to stop the engine when coming to a stop so I can reverse into a parking spot. It always gives me the idea I can't drive stick anymore.
This is where it gets complicated.
DRL's are only testable on vehicles first used after 1 March 2018.
But if the DRL's also function as position lamps, they must meet the MOT requirements for position lamps.
So (on cars used before the cutoff), you can turn them off in the menu and, irrespective of any telltale light on the dash, it won't be failed for non functioning DRL's. But if they don't do what they're supposed to do when the headlamps are turned on, they'll fail the part of the test relating to position lamps.
In the UK at least, pragmatically, I don't think a car would be failed for this.
Theoretically, a car can be failed if any part of its original emissions control equipment is missing, obviously modified or obviously defective.
But this is intended to catch folks who've removed or modified stuff which directly affects exhaust emissions, like catalytic converters and DPF's; there is no mention of any reference to the S/S system being part of the emissions control equipment.
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Piccolo Nero e Bella
Prominent member
Uhhh... right.
So glad Victoria doesn't have an MOT equivalent...
Piccolo Nero e Bella
Prominent member
I know what you mean - even after ten years I still get a mild jolt of alarm that I've somehow stalled the engine!
Its the programed half-a -second delay
before the system cuts the engine that lulls you into a false sense of non-security!!!!
before the system cuts the engine that lulls you into a false sense of non-security!!!!decappottabile
Member
It must be possible, because my 2016 car doesn't have start stop at all. I assume it's hidden in one of the bytes that's part of the proxi alignment, but it will be difficult to find out which byte it is.
You could try this but at your own risk. Nothing will break but you may have to reset a fault code / MIL light if the system spots the change and does not self reset when undone.
On the battery negative teminal is a current sensing element. Connected to this is a small connector. The purpose of this is to signal to the engine ECU/Body Computer how much charge / discharge current has been through the negative terminal. This is used a just one of the many factors effecting wwhether Start/Stop will activate. If you disconnect this little connector the the Start/Stop system will not be aware of the battery charge status and whilst still enabled will not operate as normal as it lacks the information to make a judgement.
On the battery negative teminal is a current sensing element. Connected to this is a small connector. The purpose of this is to signal to the engine ECU/Body Computer how much charge / discharge current has been through the negative terminal. This is used a just one of the many factors effecting wwhether Start/Stop will activate. If you disconnect this little connector the the Start/Stop system will not be aware of the battery charge status and whilst still enabled will not operate as normal as it lacks the information to make a judgement.
Does the fiat 500 also has a smart charge system? I know some alternators have magnetic pulleys like the ac compressor. And only when the system thinks it requires charging it actually spins the alternator insides. The other time it is just free spinning to give less stress on the engine and so getting better fuel consumption.
That's actually pretty much how a normal alternator works anyway. There's very little internal friction; the load it places on the engine is largely determined by how much current you draw from it.
If you visit a science museum, you might find an interactive display where you spin a coil by hand in a magnetic field, and then when you add an electrical load, it becomes much harder to turn.
Electrical regenerative braking works on the same principle; the current generated is used to charge a battery.
A/C compressors are different; there's much more internal friction, so having a magnetic pulley to disconnect it from the engine when it's not needed saves on both fuel and compressor wear.
Not fully researched myself but any Smart Charge Alternator is almost certainly not going to use any engaged/disengage clutch mechanism. It will be the alternator's regulator that controls the charge. Note! All alternator regulators will reduce the charge to a battery when the batterty reaches full charge voltage. This Smart Charge technology is I believe to allow the vehicle to vary or even stop the charging current, an thus engine load, depending on different factors and different electrical system loading.
Exactly. If the charging current is stopped, the additional load of a spinning alternator is minimal; there's no need for the additional cost and complexity of a disengaging mechanism.
Not so much internal friction, just load from the compressor as it works the full amount when ever spinning, compared to the electronically controlled load of the alternator.