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Like a lot of modern items that run using some kind of computer brain they often benefit from doing a 'reboot' every now and again, so do cars behave in the same way? When I start my car every morning am I booting my car's ECU up from being fully off or is it just being woken up? I ask because I've noticed that my folding mirrors do a few quirky things every so often especially first thing in the morning when maybe one will unfold but the other take an extra 30 seconds to catch up.
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Being woken up.
Proof of the pudding is the fact that most cars cannot be parked up for more than 2 weeks, before the battery gets so depleted that the vehicle cannot be started (in some cases even unlocked!)
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Depending on the car there will be modules around the car to control various functions.
The door mirrors on my car are part of a door module which can be reset independently of the rest of the car systems.
If I want to disconnect the battery I have to wait min. 10 minutes after switching off to allow the various modules to shutdown to sleep mode before disconnecting otherwise it can cause some problems when reconnecting the battery.
Last edited by: gmac on Thu 7 Feb 13 at 07:45
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The Alfa handbook warns to allow a couple of minutes before turning on the ign after reconnecting the battery to allow a check sequence. One of the things it does is to move all climate control flaps through their travel and reset the limits. You can hear it all clunking and whirring away while this happens.
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SWMBO didn't like sitting in the Octavia with the ignition off because it made all sorts of noises for five or ten minutes, must be doing similar things.
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>> The Alfa handbook warns to allow a couple of minutes before turning on the ign
>> after reconnecting the battery to allow a check sequence. One of the things it does
>> is to move all climate control flaps through their travel and reset the limits. You
>> can hear it all clunking and whirring away while this happens.
I seem to recall its a fiat weak spot, sure the motors all move, but the links to the flaps are all broken.......
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>>>I seem to recall its a fiat weak spot, sure the motors all move, but the links to the flaps are all broken.......
Don't tempt fate.
Actually the thing that has amazed the most on this Alfa, given it's 10yrs old in 2mths, is that every single one of its complex electrical/electronic/control systems is working perfectly... with the impressive dual zone climate being a good example.
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According to a chap who wrote the software for one of these ECUs, for about 30 minutes after the engine is switched off the software is still monitoring the various temperature sensors and adjusting the map to take into account how quickly various bits are cooling down, making the engine more efficient next time it's run.
The BMW used to reset the accelerator position sensor if the battery was off, making it seem remarkably spritely until it adapted to my James May approach to driving and inserted a much stronger imaginary spring under the pedal.
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I've left my Passat outside on the road for two weeks without it being driven and when I got back it was fine. Lucky really because if the battery was totally flat and I could find someone to push start it - not going to work. You need power to release the electronic parking brake.
Getting in wouldn't be a problem - although some models of modern VWs appear not to have any keyholes, you pop off a plastic cap where the lock is hidden and use the plastic key to get in. Usually of use if the remote opener is not working I guess.
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>>Getting in wouldn't be a problem - although some models of modern VWs appear not to have any keyholes, you pop off a plastic cap where the lock is hidden and use the plastic key to get in. Usually of use if the remote opener is not working I guess.
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If I have a flat battery on my X type I cannot access my jump leads that are in the boot.
The boot release is electric and there is no back up key hole or anything else.
Will a good battery,if the electric boot release fails in normal use ---??????.
Thi X type was released over 10 years ago and nothing was done about this stupid design
British engineering at its best!!!!
One way to overcome it in the USA is to smash the L/H rear light and pull the emergency release. UK models do not have this facility so not an option.
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>> You need power to release the electronic parking brake.
I thought they all had a manual overide behind a 'secret' cover.
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>> I thought they all had a manual overide behind a 'secret' cover.
>>
So did I. But because of posting in the EPB thread I checked the user manual. It says to release the brake with a flat battery you need to use jump leads!
And as said above, if your jump leads are in the boot then without central locking, the boot won't unlock will it. And there's no keyhole on the VWs for the boot. The badge is used for boot release.
What you'd have to do is open a front door, reach in and open a rear door. Drop the rear seat (they don't lock like this did on earlier Passat)... clamber into the boot and pull the emergency release mechanism for the boot.
But hang on... if the doors are deadlocked... if you open the front door with the 'emergency' plastic key, all others doors are still deadlocked aren't they? So to get into the back you'll need to clamber through between the seats because you cannot open the rear door from inside. I'd try the key but suspect VW's design means the cap does not fit back over the keyhole easily and will fall off :-)
And if you can open the deadlocked doors with the plastic key.... doesn't this suggest a weakness in the mechanism that can be exploited?
Best not to leave the car battery run flat!
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>>And if you can open the deadlocked doors with the plastic key.... doesn't this suggest a weakness in the mechanism that can be exploited?
>>Best not to leave the car battery run flat!
I do not have a plastic key but manually unlocking my drivers door will very quickly trigger the alarm unless a chipped key is put in the ignition.
Those cheap cigar lighter to cigar ligher jump leads seem to be worth exploring for use by the non mechanical folks.
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From experience on other cars, then opening mine with the key would trigger the alarm if I didn't insert the key*in the ignition slot quickly. If the battery was flat then that would not matter.
* Not sure you'd call it a key though. The whole thing goes into the slot and you press it in. The plastic key is 'hidden' in the press and drive key. The press and drive key inserted in the slot looks like this:
www.volkswagen.co.uk/new/passat-estate-vii/explore/interior/dashboard/press-and-drive-key
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>> Those cheap cigar lighter to cigar ligher jump leads seem to be worth exploring for
>> use by the non mechanical folks.
>>
Ummm a slight issue there with some cars...
The lighter circuit isn't live unless the ignition is on.
The feed via the ignition switch isn't direct, but feed via a relay/ECU, ie the lighter circuit isn't live unless there is power in the battery......
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Curiosity got the better of me... so I tried to open the car with the plastic key. I don't think it's possible with the deadlocks on (the default when locking). The plastic key would not open the car. But it would if the car was not deadlocked. It could be used to lock the car - and reading the owner manual it is then also possible to manually lock all the other doors one by one.
So if a VW owner came home and the battery was flat... how are you meant to get in to get the bonnet open to jump start it :-) I guess the AA/RAC know how to open the bonnet from outside without causing damage to the car.
But, if the battery is flat in the remote opener (and the car is fine)... you can't get in either. I am sure on some previous cars the deadlocks could be unlocked if you had the key. Maybe I am mistaken.
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>> I guess the AA/RAC know how to open the bonnet from outside without causing damage to the car.
Or if the starter motor terminals are accessable from underneath the car, just connect jump leads to them.
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The Mondeo would close all its climate control flaps each time the engine was turned off, producing several whirrs from behind the dashboard for a few seconds. I reckon it did this to prevent air currents on warm, windy days setting off the alarm's interior movement sensors.
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>> Depending on the car there will be modules around the car to control various functions.
>> The door mirrors on my car are part of a door module which can be
>> reset independently of the rest of the car systems.
>> If I want to disconnect the battery I have to wait min. 10 minutes after
>> switching off to allow the various modules to shutdown to sleep mode before disconnecting otherwise
>> it can cause some problems when reconnecting the battery.
Yes thats a wise move on any new car these days. I would, in fact leave it for 30 minutes before disconnecting the battery.
When power is reconnected, most things will now be back to factory defaults, and any learned running data will be lost. It may or not perform as well as it used to for a while.
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>> Yes thats a wise move on any new car these days. I would, in fact
>> leave it for 30 minutes before disconnecting the battery.
>>
>> When power is reconnected, most things will now be back to factory defaults, and any
>> learned running data will be lost. It may or not perform as well as it
>> used to for a while.
>>
So, when I go off for an extended holiday, the car is left in the garage. Should I:-
a. lock it?
b. leave it unlocked?
c. disconnect the battery?
d. something else entirely?
The car is an LEC, or should that be LGEC?
Last edited by: Duncan on Thu 7 Feb 13 at 08:52
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D. Leave it connected to a smart charger.
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I suppose it depends on how long the extended holiday is but I have often left my car on the driveway for up to four weeks unused and unstarted and have never encountered any problem on starting it on my return..
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One of the differences between the computers we use and the embedded controller used in cars is that the embedded controller is much more likely to have a so-called watchdog timer integrated into the processor.
If the watchdog timer isn't sent a signal from the executing code every so often, it will initiate a procedure to recover the function of the device. This can include shutting down and starting up again.
So, effectively, the monitoring and deciding on a reboot is something which is happening all the time.
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Once again, the forum reminds me why I don't buy cars with these things in them.
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>> Once again, the forum reminds me why I don't buy cars with these things in
>> them.
A luxury you won't be able to enjoy for much longer, since pretty much anything designed from the late 90s onwards has a multiplex electrical system.
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>> >> Once again, the forum reminds me why I don't buy cars with these things
>> in
>> >> them.
>>
>> A luxury you won't be able to enjoy for much longer, since pretty much anything
>> designed from the late 90s onwards has a multiplex electrical system.
>>
I've no intention of ever buying anything from the 90s onwards. 1967 is my favourite year.
I'll make an exception for the Volvo (1992).
Why design cars that flatten their batteries? Why do people buy them? It's like going back to the 1950s, the heyday of the battery charger. They'll be fitting starting handles next.
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This is far less of an issue with embedded systems that run a fixed set of functions anyway. The need for a regular reboot is caused by continually running and stopping different bits of software, all of which may have their own issues and which also requires continous allocation and deallocation of blocks of memory.
If you look at a computer server (which is effectively the same as your PC, only possibly more powerful) these will run a fixed application set of robust, enterprise grade software continuously and are quite capable of offering continuous operation for months, or even years, without significant degradation.
Wheer you could potentially get a problem is if there were a memory leak or similar bug in the ECUs software, which would cause it to run out of resource over time. This would be spotted quite quickly in operation and I'd expect a software update to have been issued within the first few months of a model's life in such a case.
I doubt your mirrors are directly controlled by the ECU anyway. I'd have thought it far more likely that they unfold automagically when the ignition's on and fold when it's off (i.e. triggered by the ignition switched feed to the vehicle's loom being live or not). The problem's more likely to be with the "slow" mirror itself, especially given the cold and damp weather and the fact the mirror's stuck out in the worst of it. My guess would be a "tired" acutating motor or solidifying grease in the mechanism.
In my experience of electromechanical systems, it's the stepper motors and mechanical bits that give up, not the electronics.
Last edited by: TeeCee on Thu 7 Feb 13 at 13:23
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The electrics on our 10-year old Citroen C8 are beginning to play up more than usual.
Usual = ocassionally the electric sliding doors don't shut because a sensor thinks there is something blocking them so they re-open. Plus ocassional 'Pollution fault' messages which I ignore.
Now = The tyre pressure sensors gave false readings (like our Merc CLK), so I had that bit disabled.
Plus when you start the car the hazard lights are on.
Plus (luckily the day after the MOT) the airbag light came on. Then it went off.
Plus the battery has nearly had it, one more hard frost may be enough.
Plus the engine has taken to running slightly cold (thermosat, I pressume).
Plus the cambelt should really be changed again soon.
Plus the Pioneer radio/sat-nav has a mind of its own at times.
And so it goes on. But it passed the MOT this week!
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New battery will probably fix all of them except the cam belt.
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>> New battery will probably fix all of them except the cam belt.
>>
^^^^ Wot he said.
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The airbag light is likley to be the connectors under the front seats.
Your battery may well have had it but check the condition of the main lead off the positive terminal. Some Citroens, including my Xantia, are prone to flex wear and corrosion at this point. Resistance rises and the conductive core gets thinner. Initial symptom similar to battery failure as starter is sucking on an ever thinner 'pipe' and not getting enough jiuce for a vigorous turn.
Eventually the cable heats up to cherry red and burns out.
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Car ECUs utilise systems on a chip so no problem just powering them off as there in no writing done to the chip unlike a hard drive in a computer, they don't need shutting down like Windows XP. Most cars keep the various ECUs on for appropriate lengths of time from a few minutes to a few days before suspending them then powering them right down to conserve battery capacity.
Last edited by: sooty tailpipes on Fri 8 Feb 13 at 22:32
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Reboot required? - swiss tony
