D4nny8oy
Established member
If that were the case, the mk2's would need a considerably heavier-duty battery than the mk1. It doesn't.
Technical What is the 'City' button for?
- Thread starter Aleks
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Technical What is the 'City' button for?
If that were the case, the mk2's would need a considerably heavier-duty battery than the mk1. It doesn't.
jontera
New member
Mine does indeed have a fault with the sensor, sometimes it will not read a speed other times it'll will just decide to show nutty random speeds, such as 80+ including at stationary(and a 99.9mpg reading). It also does turn the red warning light on occassionally. Yet another one of the on the list jobs.
At the time of the motorway incident, the speedo was showing less than 30, and the sat-nav showed around the 80ish mark.
Don't worry the punto is currently sat on the drive awaiting new top mounts and engine mounts, along with a little bit of welding...loads of jobs but no time in which to do them..
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It does need a heavier duty battery to run properly!
The standard battery just about does the job, there is plenty of extra power in the mk1 battery's.
D4nny8oy
Established member
The standard battery does fine because it doesn't run off the battery while the engine's running!
It's well known that if the alternator isn't charging, the PAS is the first to stop working because it needs to see alternator voltage (13-14 volts) before it will activate (turn the steering before and during start-up and you'll feel when it kicks in). Even with all electrical loads on, there's always enough spare capacity in the charging system to cope.
It's lack of use in cold weather which kills batteries more.
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The PAS does use the battery at parking speeds because with the engine on tickover (more or less) the generator is not making much power so the battery has to take up the slack. Once moving the PAS doesnt have to do very much work so wont pull much power.
The generator will of course soon top up the battery, but at low engine speeds the battery is there to fill that power gap. A heavy duty battery will get less stressed than a small or cheap battery (not necessarily the same thing) so it will last longer.
If you want proof, fit a worn out battery with minimal charge capacity and watch in awe at how the power steering trips out and the lights go dim on tickover. It's fine if you rev the engine 1500-2000 rpm.
The generator will of course soon top up the battery, but at low engine speeds the battery is there to fill that power gap. A heavy duty battery will get less stressed than a small or cheap battery (not necessarily the same thing) so it will last longer.
If you want proof, fit a worn out battery with minimal charge capacity and watch in awe at how the power steering trips out and the lights go dim on tickover. It's fine if you rev the engine 1500-2000 rpm.
Thank you! Someone who is better with words than me
D4nny8oy
Established member
I don't get what you're saying.
If the battery is knackered, then yes, the charging system is running flat out to recharge it, so the PAS struggles to work, as do the lights and any other electrical load. But the PAS, CITY mode on or off, doesn't kill batteries!!
The charging system still produces 13-14v @ idle, so the PAS won't run down a good battery on tickover.
If the battery is knackered, then yes, the charging system is running flat out to recharge it, so the PAS struggles to work, as do the lights and any other electrical load. But the PAS, CITY mode on or off, doesn't kill batteries!!
The charging system still produces 13-14v @ idle, so the PAS won't run down a good battery on tickover.
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Its all about pressure (volts) and flow (current) - power is a function of both. Useful power from a car generator wont happen at tickover.
The charging system makes the voltage at idle but its wont make much current as the generator isnt turning fast enough. Its the current demand that's provided by the battery when the generator cant deliver. Agreed, a good battery will be fine.
In the winter with heated window, lights, heater fans and power sucked out to start the car the battery can struggle. Add in the cold weather and no battery will deliver its full charge (chemical reactions work best when warm). Use a cheap/old one and you get what you pay for.
The charging system makes the voltage at idle but its wont make much current as the generator isnt turning fast enough. Its the current demand that's provided by the battery when the generator cant deliver. Agreed, a good battery will be fine.
In the winter with heated window, lights, heater fans and power sucked out to start the car the battery can struggle. Add in the cold weather and no battery will deliver its full charge (chemical reactions work best when warm). Use a cheap/old one and you get what you pay for.
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D4nny8oy
Established member
Once the initial start-up phase is over and the engine is running, all systems are driven off the alternator and what is left is used to top-up the battery. The internal regulator in the alternator adjusts what is supplied depending on the demand.
The alternator output @ idle is sufficient for the PAS to operate without killing the battery, as you said yourself- if the battery voltage is weak, the PAS will operate sporadically. So therefore (if the system is really on it's knees @ idle) and the theory is correct, activating the 'CITY' mode will see the PAS shutdown. But it doesn't, because there's enough reserve capacity in the charging system to cope with the intermittant demands of the PAS.
Fiat would look pretty stupid if the charging circuit couldn't handle the 'CITY' button being used when stationary (as it was designed to do- providing extra assistance when manoevering slowly/stationary).
People seem to think pressing the 'CITY' button instantly increases the voltage/current delivered to the PAS motor- it doesn't. It merely alters the point at which the assistance begins (for a rough example, when only 3Nm of torque is sensed instead of 6Nm). It's only for that very short period when the steering is turning and the resistance load is against it, that the motor is supplied. Once the steering movement is stopped, or the vehicle is moving (which decreases the resistance to turning and therefore the torque felt by the column) the voltage/current supplied to the motor is zero.
T and myself have worked on hundreds if not thousands of Punto's over the years, and agree that there is no correlation between usage of the CITY button and the lifespan of the column or battery.
The alternator output @ idle is sufficient for the PAS to operate without killing the battery, as you said yourself- if the battery voltage is weak, the PAS will operate sporadically. So therefore (if the system is really on it's knees @ idle) and the theory is correct, activating the 'CITY' mode will see the PAS shutdown. But it doesn't, because there's enough reserve capacity in the charging system to cope with the intermittant demands of the PAS.
Fiat would look pretty stupid if the charging circuit couldn't handle the 'CITY' button being used when stationary (as it was designed to do- providing extra assistance when manoevering slowly/stationary).
People seem to think pressing the 'CITY' button instantly increases the voltage/current delivered to the PAS motor- it doesn't. It merely alters the point at which the assistance begins (for a rough example, when only 3Nm of torque is sensed instead of 6Nm). It's only for that very short period when the steering is turning and the resistance load is against it, that the motor is supplied. Once the steering movement is stopped, or the vehicle is moving (which decreases the resistance to turning and therefore the torque felt by the column) the voltage/current supplied to the motor is zero.
T and myself have worked on hundreds if not thousands of Punto's over the years, and agree that there is no correlation between usage of the CITY button and the lifespan of the column or battery.
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The steering points make sense though the motor will be taking more strain in City mode than in normal.
The net charging issue will be proved by looking at the alternator output curves. Unless its seriously unusual, at low revs, the power (not voltage) output will be minimal.
The net charging issue will be proved by looking at the alternator output curves. Unless its seriously unusual, at low revs, the power (not voltage) output will be minimal.
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who's going to be the one that drives round crawling and turning left-right constantly to see if there battery goes flat
probably not.. and lets not forget the lights are 50watt each and a 50watt stepper type motor would be very powerful
probably not.. and lets not forget the lights are 50watt each and a 50watt stepper type motor would be very powerful
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I was thinking of dissing the city switch from the steering and wiring it to an illuminated sign on the rear valence that show "Caution - woman driver" in yellow and black (compliant with BS5499 - safety signage). However, a policeman says it would be illegal. Apparently it has to be red and white.
84000 miles, car 7 years old on original battery and city button has always been on,elec steering still works ok and battery still healthy under discharge test
seaside cat
New member
Is there any way of disabling the city button? I never use it. The steering on my 500 is so light I can't see why on earth I'd need it any lighter! Anyone who can't park without it shouldn't be driving!! I'm afraid of it getting pressed by accident so is there any way of completely disabling the feature?
i would physically disable the button, rather than cutting any wires or the button itself.
you could do this by stopping the button being pushed in, maybe use some matches glued to the back side of the button, so if it is pushed, it cant go in, therefore cant hit the switch to trigger the city mode.
would be the simplest option, and could easily be removed if needed.
you could do this by stopping the button being pushed in, maybe use some matches glued to the back side of the button, so if it is pushed, it cant go in, therefore cant hit the switch to trigger the city mode.
would be the simplest option, and could easily be removed if needed.
seaside cat
New member
Thanks for that idea, I wouldn't want to fiddle with the wires or it will probably either go up in smoke knowing my luck or a load of coloured lights will come up on the dash! but stopping the button being pressed is the safest way. I will see what I can do. If anyone else has done this please let me know how!
but stopping the button being pressed is the safest way. I will see what I can do. If anyone else has done this please let me know how!
D4nny8oy
Established member
Seriously???
How do you manage to leave the house without worrying about being hit by random objects falling from the sky?
And why post a 500 question in the Punto section?
How do you manage to leave the house without worrying about being hit by random objects falling from the sky?
And why post a 500 question in the Punto section?
Seriously???
How do you manage to leave the house without worrying about being hit by random objects falling from the sky?
And why post a 500 question in the Punto section?
If you accidently hit it which i would find it very hard to do why not just switch it off?
the cars been designed to work with the city button on for years no doubt so one unlucky switch on or off wont hurt it 
