Alternator, self excitation voltages.

Greetings all.
A few days ago I had the battery light come up, then disappear, then come up again to stay. (First time this has happened).
I'm sure the battery went almost completely flat while driving but still had enough power for the ECU and steering, however, as expected, the ABS and airbag light started showing.

I pulled up and switched the engine off and went to re-start. Nothing, starter-solenoid clicking, clock reset. The end...

Three days later the car's now at home. Battery charged, engine running, no battery light, Lexia connected, loads of fault codes erased, no new ones...
Alternator self-excitation reading 0.8 Volts, battery read 12Volts. Engine running a little rough...

Just to be 100% sure, do I need a new alternator or does the ECU control when the alternator needs to charge and power the vehicle -- is this was just a Citroen thing...

Car info: C3 1.4 HDi 16v.

Many thanks,


Adam

Adam wrote:Greetings all.

Hello Adam

Adam wrote:Just to be 100% sure, do I need a new alternator or does the ECU control when the alternator needs to charge and power the vehicle -- is this was just a Citroen thing...

I can say that the Haynes manual shows 2 different circuits for petrol and diesel alternator control, but they both end up having a computer connection. The petrol is to the engine ECU and the Diesel has it to the BSI.

It may be worth looking in lexia to see if there is a load-shedding restriction on the alternator and if there is an alternator enabled flag to be sure its actually the alternator and not the computer.

Sorry, I can't be 100% at the moment. I may be able to gain some more information on Monday.



The live data screen to capture Alternator excitation voltage and many other power systems on the C3

Load shedding on a Diesel C3
I didn't see any load shedding for the Alternator

Hey Arfur,
As the weather was good this afternoon I really got stuck in.
From my findings it was the alternator.
Look at the top slip ring in the pic...
I'm just going to clean and polish both slip rings and fit new brushes.

I sat in the car with the engine running with every thing on bar the Radio... A/C, all lights on, rear demist.
On Lexia I was in the BSI - Peramitures menu. And basically watched the battery voltage drop till the engine cut out... At 6 Volts!!!!

I'll add in the screen prints below.

Having not removed an alternator from my C3 it was a bit of an ordeal. Something I anticipated would of only taken 20 minutes. Not as the case.
Had to remove the off side wheel arch cover, A/C compressor (hoses left institute), A/C mounting bracket and serpentine belt tensioner.
Now I know the order of the things that need to come off. It shouldn't take as long as I did, an hour of fiddling... To anyone else reading this, I would really recommend as nice set of ratchet spanners as I don't have any, these would really speed things up so much.

Adam.

Worn slip rings on a C3 alternator
Engine Off
Engine Start
Load shedding Engine Off
Load Shedding Engine On
Engine On - Load - Battery Light On
Engine On - Load - Battery Light on - ABS A/C 1
Engine On - Load - Battery Light on - ABS A/C 2
Engine On - Load - Battery Light on - ABS A/C 3
Engine On - Load - Battery Light on - ABS A/C 4

Alternator not charging battery fault on a Citroen C3

I think this one hits the nail on the head, you got your moneys worth out of those slip rings !!

Thanks for all the screen shots from lexia showing all that information. I have annotated your images based on the file names you gave them.

Adam wrote:Having not removed an alternator from my C3 it was a bit of an ordeal. Something I anticipated would of only taken 20 minutes. Not as the case.
Had to remove the off side wheel arch cover, A/C compressor (hoses left institute), A/C mounting bracket and serpentine belt tensioner.
Now I know the order of the things that need to come off. It shouldn't take as long as I did, an hour of fiddling... To anyone else reading this, I would really recommend as nice set of ratchet spanners as I don't have any, these would really speed things up so much.

Thank you for the information

Hey Arfur,
It did indeed, 142K on a 52plate, hats off to Valeo!
Most would give up on the old C3, it still pulls really well. I intend to keep it going for many more years.
Went to clean that top slip ring but it's warn to the plastic, such a shame as new brushes are just over £4

Adam.