alternator issues

Talk about the 406's electrical system, what wires do what, how to add extra functionality, etc.

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cliffk
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alternator issues

Post by cliffk »

2001 406 diesel estate
Hi All
Had the AA out today as I stopped partway through my journey and when I tried to start the battery was flat.
Great service from the AA the guy got me started and proceeded to fault find as there was no charge, he eventually jumped a cable from the battery + to the small connection on the alternator and the alternator kicked in.

His conclusion is that there is a fault with the small cable going to this connection (he did a reading between the small connection and the battery and the value was 1.6 and it should be 0.2 or less (totally over my head)) Apparently when the ignition is turned on this cable should give a signal to make the alternator charge, he traced the cable as far as he could to look for damage but couldn't easily find any. In my case this cable is red and white.

Presently I can keep myself out of trouble as I have a length of cable and by jumping + to small connection on the alternator every time I start the car it will charge.
I have checked this myself by starting the car and the reading across the battery is just over 12 volts (alternator not charging) jump the terminal briefly and the reading goes to just over 14 volts (alternator charging).

Has anyone had this problem and fixed it?? I am no auto electrician.
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Doggy
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Re: alternator issues

Post by Doggy »

Looks like the alternator auxilliary connection comes from the BSI, (terminal 14 of the 26-way yellow connector if Haynes is to be believed for once).

Maybe one of the BSI relays is faulty or you have a fuse gone, (anything else not working)?

Worth checking all the fuses if you can, I would start with the ones on the outside of the BSI, (5 I think).
Probably try the engine fusebox next, then the one in front of the BSI
(Obiously you can discount any where you know or can work out what they do and those bits still work).

Sorry I can't be more specific but I no longer have access to any diagrams.

Does your alternator warning light come on before you start the engine / with engine running and not charging / after you kick the alternator into life?
2002 HDi 2.2 Exec Estate, (2008-12) (wonderful)
2003 HDi 2.2 6-speed Exec Estate (2012-19) (also a gem)
2009 Citroen C5 2.0 HDi VTR+ Estate (godawful heap)
2008 BMW E91 330i touring (great fun - murdered by a reversing SUV)
2007 BMW E91 325i touring (slower smoother quieter)
cliffk
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Re: alternator issues

Post by cliffk »

thanks for that info being a complete car electrics novice I do not know where to find the BSI or what it is.

Everything else appears to be working EML has been on for ages and flags up a notice particulate filter on start up, it doesn't seem to stop anything working, had this fault before and have pp2000 on an old lap top with windows XP managed to access ECU last time and clear it but now cant get the pp2000 to run so thats annoying.

On ignition Batt light comes on but goes off once engine running even if I dont jump the alternator to the battery.

AA man checked all the fuses in the engine bay and all were good.
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Re: alternator issues

Post by cliffk »

Sorry I gave wrong info there

Battery light is on when engine is started and stays on when Ive jumped the alternator and it is actually charging.
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steve_earwig
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Re: alternator issues

Post by steve_earwig »

So alternator output is controlled by the BSI, I didn't actually think they were that "advanced". Umm, my fuse diagrams for a full-mux say fuse 16 in the engine fuse panel, which the AA man checked. :frown:
Unskilled meddling sin©e 2007

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Doggy
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Re: alternator issues

Post by Doggy »

I'm not sure either - I'm guessing the AA man tested continuity between the alternator aux connection and the battery +ve and found a higher resistance than he expected, (possibly an open relay contact with a snubber/suppressor across it, or maybe just a dirty contact or other poor joint).

The warning light being on when it's charging implies the alternator auxilliary, (a.k.a. 'warning light') terminal is no longer connected to the control unit in the instrument cluster, or whatever that gets its info from - proabably the BSI

(BSI = Body Systems Interface; a computer system that handles all the stuff done by discreet relays etc, on older cars e.g flasher unit, hrw relay/timer, central locking control, low + main beam headlights, interior lights, wipers, washers and a so on).

:idea: I guess a BSI reset would be worth a try. https://www.406oc.co.uk/viewtopic.php?f=10&t=10968

Failing that, I would rig your temporary jumper to a convenient pushbutton or similar in the short term.
2002 HDi 2.2 Exec Estate, (2008-12) (wonderful)
2003 HDi 2.2 6-speed Exec Estate (2012-19) (also a gem)
2009 Citroen C5 2.0 HDi VTR+ Estate (godawful heap)
2008 BMW E91 330i touring (great fun - murdered by a reversing SUV)
2007 BMW E91 325i touring (slower smoother quieter)
cliffk
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Re: alternator issues

Post by cliffk »

Thanks for that doggy you are correct with this (I'm guessing the AA man tested continuity between the alternator aux connection and the battery +ve and found a higher resistance than he expected), I wasn't sure what he was measuring but the reading he got was 1.6 when he was expecting 0.2 or less so that must have been the resistance figure.

Just tried the BSI reset as per the instructions and unfortunately no improvement so I do have a plan as per your post to rig a cable between the small connection and the battery, I don't have a push button which would be ideal but do have a toggle switch to insert into the cable so plan to use that so a quick on off of the switch will kick the alternator in, if I can run with that for a few days it should get me to the stage where either I will have more time to get in depth or find someone cleverer than me to sort it.

Out of interest where would I find the BSI?

Thanks for your time and information
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Doggy
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Re: alternator issues

Post by Doggy »

For BSI location, have a look at this video https://www.youtube.com/watch?v=HvZLewcIGtA

You can briefly see the fuse holders on the outside of the unit just as he yanks it out.

To be clear, I'm not trying to say your BSI is at fault, all we really know is:

1. The aux terminal on the alternator is not getting the 12V supply it needs to start charging, (alternators don't have residual magnetism / need to have the rotor coils energised to produce an output from the stator windings, but once it's producing power a separate internal rectifier feeds the rotor directly, so it will keep working until the engine stops).

2. The 12V output from the aux terminal isn't being detected by the car, hence the warning light staying on.

This is why the AA man suspected a break in that wire.
2002 HDi 2.2 Exec Estate, (2008-12) (wonderful)
2003 HDi 2.2 6-speed Exec Estate (2012-19) (also a gem)
2009 Citroen C5 2.0 HDi VTR+ Estate (godawful heap)
2008 BMW E91 330i touring (great fun - murdered by a reversing SUV)
2007 BMW E91 325i touring (slower smoother quieter)
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Re: alternator issues

Post by steve_earwig »

The AA guy was probably measuring volt drop, so it's not completely borked, just borked enough to stop it working. I presume he'll have tried reseating the fuse. I suspect you'll be looking for a green and crusty connector, er, somewhere.
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cliffk
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Re: alternator issues

Post by cliffk »

thanks again guys and thanks for the explanation on how the alternator works which makes me understand why jumping to the battery kicks it in and it keeps going.
Yes Steve I probably expect its a crusty joint somewhere, a few years ago I had the connector under the carpet issues and removed it completely soldering the respective cables together and covering with heat shrink, at that time I only did the big connector there were a couple of smaller ones there if I remember right that seemed OK I suspect this area is still getting wet and my problem only really started after the heavy downpours we had at the weekend so I plan to lift the carpet again and see if there's a problem there.

Meanwhile I've rigged a cable with a toggle switch between the alternator and battery +ve so a flick of the switch kicks the alternator in, bit of a pain lifting the bonnet every time I start the car but it keeps me going.
cliffk
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Re: alternator issues

Post by cliffk »

just watched the video on BSI removal that looks like a last resort :( :(
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Doggy
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Re: alternator issues

Post by Doggy »

I was really just trying to answer your question on where it lives.
2002 HDi 2.2 Exec Estate, (2008-12) (wonderful)
2003 HDi 2.2 6-speed Exec Estate (2012-19) (also a gem)
2009 Citroen C5 2.0 HDi VTR+ Estate (godawful heap)
2008 BMW E91 330i touring (great fun - murdered by a reversing SUV)
2007 BMW E91 325i touring (slower smoother quieter)
cliffk
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Re: alternator issues

Post by cliffk »

Ha yes I appreciate that I see it lives in a very difficult place I assume the fuses are accessible at the bottom of the fuse panel.
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Doggy
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Re: alternator issues

Post by Doggy »

To be honest, I have never changed one of those fuses so don't really know.
It may be possible to move the some sections of the passenger cabin fusebox in front of it - think I saw the lower section moving in the video.

Obviously a good idea to disconnect the battery before trying, observing the process to let all the ecus shut down first as in the BSI reset procedure
2002 HDi 2.2 Exec Estate, (2008-12) (wonderful)
2003 HDi 2.2 6-speed Exec Estate (2012-19) (also a gem)
2009 Citroen C5 2.0 HDi VTR+ Estate (godawful heap)
2008 BMW E91 330i touring (great fun - murdered by a reversing SUV)
2007 BMW E91 325i touring (slower smoother quieter)
cliffk
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Re: alternator issues

Post by cliffk »

Yes sure first though I'm going to see how the cables under the carpet look had a couple of other errors pop up today and then disappear (air bag and abs) notice on the screen and warning light then they went off again and didn't reappear. So gremlins somewhere, which may well be related.
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