Evening all, My Dad's 406 TDLX has developed a problem. when the key is in and on click1 click 2 and turned over the battery light is on and dim. Turn it off and the battery light goes too (great).
I have made some readings with a Volt meter.
Battery engine off= 12v
Battery engine on= 11.9v
Volt test on alternator D+/D- =6.3v
This points to an alternator right?
Could some one let me know if I should make an alternator sized hole in the garden please? (I don't fancy digging a 406 sized one )
Certainly sounds like no output from the alternator, but the problem may lie elsewhere.
You can get the same behaviour with bad connections between alternator & battery or even a poor engine earth.
If all your wiring was OK, you should get, (almost), the same voltage at the alternator as you have at the battery, regardless of alternator condition.
To eliminate a suspect earth, try connecting a jumper lead from battery negative terminal to alternator casing.
Hope this helps....
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)
Ack, you solve one problem and another crops up. Driving to work this morning my battery light came on. It appeared to be about half the usual brightness.
When I parked up at work I killed the engine. Upon turning the ignition through 1 and 2 the light came on as usual but was dim. When I gunned the starter the battery light diasappeared - as usual - but came back on and stayed on as the engine caught.
I'm just hoping like hell there'll be enough juice to start it again this afternoon. I'm off the rest of the week but it's a long walk home from here.
So, diagnostics: I should check voltage at battery with engine off and then battery and alt with engine on? Also I'll have a look at the Haynes wiring lies later but is there a direct connection betwixt the alt and batt so I can check continuity?
I'm loathe to tell the wife the alternators gone, having just shelled out for a new clutch. She'd probably want me to take the 6 out back and shoot it...
To sumarise: Grrr.
The man with no car
"Close the door on your way out, and don't forget your monkey."
I once shelled out for a new alternator only to have the problem you describe re-appear the following day
Turned out, in this case, to be a bad engine earth connection, so 1/4 turn with a spanner fixed it where £85 at 1986 prices failed.
There should be a very low resistance path from battery -ve to alternator casing and similarly from battery +ve to alternator +ve output connection. I'd always make sure on these before spending any money.
Easy checks include making sure you've got the same voltage across the alternator as the battery with engine running and some electrical load on. As for the earth, put a jumper lead from the battery earth terminal to alternatior casing and see if it makes any difference.
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)
Right, thanks Doggy. Today I checked battery, gave 12.65V steady. There was 0.8 ohm between battery postive terminal and the alternator so that seems ok.
Had a look at the auxi belt and that seemed ok - no cracks and reasonably tense, to my amateur eye.
Tomorrow I can perform the other checks you described and I'll nip up the alternator connections too. Two questions - when you say alternator casing, you refer to the slotted cage surrounding the windings? And would I need to scratch up some bare metal to get a fair test? Secondly, where is the engine earth located and am I going to need triple jointed arms and tiny hands to get a spanner on it? :p
TYIA
The man with no car
"Close the door on your way out, and don't forget your monkey."
Oh, and does this light indicate that the alternator is dodgy or actually fuct? I mean, will it still be charging the battery at all? Cos now I'm wondering how many starts I've got left before I need to tap the wife's car for a kick start ^^
The man with no car
"Close the door on your way out, and don't forget your monkey."
swiss wrote:Two questions - when you say alternator casing, you refer to the slotted cage surrounding the windings? And would I need to scratch up some bare metal to get a fair test? Secondly, where is the engine earth located and am I going to need triple jointed arms and tiny hands to get a spanner on it?
1. Any cleanish bit if the casing will do - you're just trying to make sure the two are definetly connected while you see if there's any significant change in battery volts.
2. I've never looked on a 406, but I think the heavy cable from the battery -ve terminal attaches somewhere near the starter.
With the engine stopped, fully charged you should get 2.2 V / cell (13.2 V). fully discharged = 1.9 Vpc - 11.8V is flat as witch's tit.
With the engine running, you should see about 14 - 15V. AFAIR. The important thing is that the battery is being charged, (i.e. battery terminal volts > 13.2), with a reasonable amount of electrical gear on at say 1500 - 2000 engine RPM.
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)
Hmm. Good continuity between battery negative and alternator casing. Predictably, therefore, jumping them made no difference. Also, switching all the electrics on and revving up the engine produced 11.22V at the battery
Additional factage: there's a buzzing comming from behind my dash cluster and the battery light is flickering in time with the buzz. I was hoping it was the battery bulb shorted and sparking a little, so I pulled the cluster. Everything looked fine back there but now I realised the buzzing was deeper in the driver's console and very possibly a rapdily clicking relay. This only happens when the engine is on, otherwise the battery light is steady, and it's only happened since the battery light first came on yesterday.
The man with no car
"Close the door on your way out, and don't forget your monkey."
Sorry to hear that, Tom. I don't have access to a D8 diagram so can't look for whatever that might be
Did you manage to check the voltage at the alternator under load? If it's the same as the battery an alternator problem is the only reasonable explanation. If it's OK, or varying, bad connections somewhere are probably favourite.
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)
I didn't check the voltage at the alt, only the battery. Will finish tea and cig and go test.
Meanwhile, just in case can you guys please check this and this to confirm they're suitable. 20 quid for a working second hander seems preferable to 100+ for a recon
The man with no car
"Close the door on your way out, and don't forget your monkey."
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