Battery removal C5

jmd · Post by **jmd** » 26 Dec 2006, 13:33

Is it true that the battery on the C5 can be disconnected, & reconnected without needing a code for the Radio. Bought the car second-hand & did not receive a code-told it's not needed. Is this true? The car is a level 2. 2.0 Hdi Year 01.

JohnD · Post by **JohnD** » 26 Dec 2006, 15:14

Yes - When the onboard computer plays up quite often if the battery is disconnected for ten minutes, the computer rights itself.

PowerLee · Post by **PowerLee** » 27 Dec 2006, 18:14

The C5 is multiplexed.

Multiplexed Peugeot / Citroen stuff doesn't have a radio code as such, The radio is locked to the BSI unit via the cars VIN number.

As long as the radio stays in the original car it was fitted to at the factory then you can disconnect the battery as many times as you like & the radio will still work fine on reconnection.

jmd · Post by **jmd** » 28 Dec 2006, 01:59

thanks PowerLee & JohnD for the advice, job completed. If their was more room to replace a light bulb it would not be necessary to remove the battery. Thanks again.

TOMTOM · Post by **TOMTOM** » 04 Jan 2007, 10:15

On the subject of battery removal - my local Citroen dealer recommended
that when reconnecting the battery the headlights should be in the switched on position to absorb any surge. I don't know how important this is but it wouldn't hurt to do it anyway.

jeremy · Post by **jeremy** » 04 Jan 2007, 11:06

Interesting idea Tom - I thought C5's were multiplexed - which would mean that the computer would have to fire up to operate the headlamps. Perhaps headlamps are not on the multiplexing?

Good idea for cars with normal (or should I say traditional) wiring and switches.

JohnD · Post by **JohnD** » 04 Jan 2007, 11:33

My headlamps which are programmed to automatic don't come on until after the engine has started.

PowerLee · Post by **PowerLee** » 04 Jan 2007, 17:25

TOMTOM wrote:On the subject of battery removal - my local Citroen dealer recommended
that when reconnecting the battery the headlights should be in the switched on position to absorb any surge. I don't know how important this is but it wouldn't hurt to do it anyway.

Just a precaution so you dont fry the BSI unit, not heard of hardly any BSIs that have been fried by reconnecting the battery.

Jump boxes or jump leads are a good way of frying your BSI though.

BonceChops · Post by **BonceChops** » 04 Jan 2007, 17:54

PowerLee wrote:Jump boxes or jump leads are a good way of frying your BSI though.

I am interested to know why jump leads would cause a problem. Does anyone have any idea why?

PowerLee · Post by **PowerLee** » 04 Jan 2007, 18:48

If the cars battery is flat / very low & you go & stick a jump box or jump leads on it the sudden surge through the CAN system can cause the BSI unit to have a major & expensive sulk

np · Post by np » 04 Jan 2007, 19:27

My stereo in the 406 is coded to the car the same as the C5.What would happen though if it packed up & i needed a new unit?How would you go about getting a replacement coded for the car?
It was just a thought i had.
Cheers

PowerLee · Post by **PowerLee** » 04 Jan 2007, 20:36

Peugeot / Citroen dealer with proof of purchase or a car audio place with correct software / kit to change stereo code VIN number

All it is coded by is the 17 digit cars VIN number, If the stereo & BSI VIN numbers dont match you get a lovely BEEP out the stereo once a minute, drives you nuts so ive been told lol

JohnD · Post by **JohnD** » 05 Jan 2007, 08:58

PowerLee wrote:If the cars battery is flat / very low & you go & stick a jump box or jump leads on it the sudden surge through the CAN system can cause the BSI unit to have a major & expensive sulk

So, apart from a slow charge of the battery, how do you start?

BonceChops · Post by **BonceChops** » 05 Jan 2007, 09:27

PowerLee wrote:If the cars battery is flat / very low & you go & stick a jump box or jump leads on it the sudden surge through the CAN system can cause the BSI unit to have a major & expensive sulk

Why would that be any different to disconnecting the battery then reconnecting it again?

jeremy · Post by **jeremy** » 05 Jan 2007, 11:15

You start to get into the wonderful world of eddy currents and all sorts of wonderful things here.

The problem is probably due to the difficulty of making good connections with crocodile clips - which as you know will often spark under load - for example when jump starting a car. This will cause a rapid on-off heavy current - which is where the fun starts.

many of the components in an car electrical curcuit can function in other ways - for example coils of wire are can behave in many different ways - for example an ignition coil will produce a very high voltage current. Its basically 2 coils wrapped together round an common iron former - and it produces the spark when the current is turned off in one coil.

Now look at your car - in the starter there is an iron former with a coil wrapped round it - linked to other coils. Now this isn't set up to produce sparks like an ignition coil - but under the right circumstances it could have a damn good try.

There are loads of components in your car - and ECU's are not cheap and difficult to diagnose.

This is just an example but these things can and do happen - just look at the multi-million £ surge protection industry. I've been using computers for 20 years now and never got round to buying one - so the risks must be real and common.