57 replies to this topic

[ghand]

Are you getting the lovely battery light on the dash on start up?

Better not be as that just tells you the alternator is shagged and we need go no further

Would this light go out after the key is initialy turned (like most of the lights do after around 5 seconds) or would the battery light stay on permanently?!

The light will stay on if not charging as its the voltage from the alternator that keeps it off, hence no alternator output and the battery will power up your warning light all the time till its flat

[VXTyrant]

Quite possibly. Which is why I would check with a meter both the voltage on the battery with the engine running and the resistance between the alternator and battery. Should give a good indication whether there is a break or not.

Where do I connect to on the alternator?

[Sutol]

tried tightening up your battery conns

[VXTyrant]

tried tightening up your battery conns

I'd just changed the battery in the last month because of my issue of losing charge and made sure everything was tight. Same things happened with both batteries so it indicates the problem lies elsewhere..

[turbobob]

Just seen this, sorry. There will be a few wires coming out of the alternator. The two thick wires are the ones you need to be measuring the output on. If they are colour coded (I haven't looked on the VX), but they should be red and black. The black is likely to be short and connecting metalwork / metal bodywork. This will be the ground. The red wire is likely to run to a regulator. But measure the voltage across the red and black. If that's ok, then you need to measure the output of the regulator.

[ghand]

Just seen this, sorry.

There will be a few wires coming out of the alternator. The two thick wires are the ones you need to be measuring the output on. If they are colour coded (I haven't looked on the VX), but they should be red and black. The black is likely to be short and connecting metalwork / metal bodywork. This will be the ground. The red wire is likely to run to a regulator. But measure the voltage across the red and black. If that's ok, then you need to measure the output of the regulator.

Isn't the regulator built into the alternator ? I would think the large red cable from the alternator would go direct to the battery or via a large fuse on some cars

[bbd]

It's not easy to get to the connections on the alternator, just check at the battery. P.S. when attempting to remove the alternator don't try and get out the long bolt, but take the bracket that it bolts through off the block this is much easier Oh, and as usual with the VX prepare for skinned knuckles

[VXTyrant]

It's not easy to get to the connections on the alternator, just check at the battery.
P.S. when attempting to remove the alternator don't try and get out the long bolt, but take the bracket that it bolts through off the block this is much easier

Oh, and as usual with the VX prepare for skinned knuckles

If it is the alternator how best to tackle it? Presume it's via the wheel arch?

[ghand]

Yes wheel arch,but if your ignition light is not on then it must be charging,well should be.You need to get the voltage checked when running.As said 14 ish volts at the battery when running. How long does it take to drain flat ?

[VXTyrant]

How long does it take to drain flat ?

Don't know as I place it on the Ctek trickle charge almost every night. According to Scanguage (I know it may not be too accurate for voltage) it's dropping to 11.5 in about 2 days (just to and from work so only 4 starts). I'll test the voltage at the battery at the weekend when I get a chance. Thinking there may be a connection issue between battery and alternator but I suppose I'll know more once the voltage is measured

[turbobob]

I was thinking this. But I haven't seen the vx alternator. And I was also thinking there may be a fuse. But I've nevertheless come across a fuse between alternator and battery blowing. Personally I would verify the output voltage and if that's ok the link first. You could find you change the alternator and find that wasn't the problem (although it does sound like it is)

[christhegasman]

I know this is a basic check and I await the abuse from those more knowledgeable😃 But with the car ticking over in the dark stick everything electric ion and raise the engine speed the lights should visable brighten at least the alternator is doing something It they progressively get darker after a while alternator is not doing much Not tried this on the vx but worth a try

Edited by christhegasman, 19 April 2012 - 09:59 AM.

[ghand]

I know this is a basic check and I await the abuse from those more knowledgeable��
But with the car ticking over in the dark stick everything electric ion and raise the engine speed the lights should visable brighten at least the alternator is doing something
It they progressively get darker after a while alternator is not doing much
Not tried this on the vx but worth a try

abuse no that works, from not running to a fast tick over you go from 12 v to 14.5 ish and like you say visibly brighter lights

Whats odd is no ignition light should indicate alternator is charging.So its either not suppling the battery ie a bad connection or something is draining the battery.

May be the glove box light again

Edited by ghand, 19 April 2012 - 03:45 PM.

[VXTyrant]

Righteo guys. Thought I'd use the multimeter to test voltage as it was struggling to start when I got out from work. It had been on charge all last night and had only been started twice today and used for around 30 mile. 

It was measuring 12.1 at the terminals with the engine off (must've been drained due to the days trip). When turning the ignition on it dropped to around 11.9 and then wouldn't start up. Got it running using me ma's mini and tested the voltage at the terminals. Again it was 12.1 ish and would rise by .1 at best, when revving, but no further. 

Also tested on the mini to make sure it wasn't the multimeter and that displayed 14.8 with the engine running!

So it doesn't appear to be getting charge from the alternator. As someone suggested earlier I was going to test the alternator, however, I couldn't find the wires necessary to connect to. Are they housed in the black box on the image below? 



Next suggestions would be a huge help guys (will try and test the alternator at the weekend)

[bbd]

Personally I'd take it off and get it refurbished, Have a look in your local yellow pages/internet for Auto electrical repairers. I had mine refurbished last year ( new diode pack ) for £50. Hope this helps.

[ghand]

I may be wrong but I think its imposable to test the thing at the alternator with it running One small wire must have a 12v feed from the battery (to excite the alternator) then the large cable has the 14 v on it which is the High current output feed to the battery, But can you get a meter on them with the thing wizzing round and keep your fingers ? Mine is the na and may be different looking at that pic.

Edited by ghand, 24 April 2012 - 07:21 PM.

[VXTyrant]

Personally I'd take it off and get it refurbished, Have a look in your local yellow pages/internet for Auto electrical repairers.
I had mine refurbished last year ( new diode pack ) for £50.

Hope this helps.

I've heard it a right pita to remove and I'd rather eliminate anything I can before taking that step

[bbd]

I defy anyone getting near those terminals with a test meter, just rip it off and get it tested, 99% sure it's shot.

[VXTyrant]

Is there any decent guide as to how to go about removing it?! Edit: also, does anyone know how much a new unit would cost (from Autovaux or similar)?

Edited by VXTyrant, 24 April 2012 - 07:48 PM.

[bbd]

From what I remember, 1, Disconnect battery. 2, Jack up and remove osr wheel arch liner. 3, Remove aux belt. 4, Undo the bracket onto the alternator, that can be seen from under the arch. 5, I found it far easier to remove the bolts ( I think there was three) that hold the main alternator bracket onto the block( standing at the back of the car and feeling under the alternator inside the bracket you will feel the bolt heads) than trying to remove the long bolt that goes across the bracket. It will help if you have a hand when removing the bracket, ( someone to hold the alternator up) 6, Turn the alternator around and remove the nuts that hold the cables on the back from above. 7, From what I remember it then comes out from underneath. 8, Pour beer. 9, Wipe blood from skinned knuckles.

Edited by bbd, 24 April 2012 - 07:51 PM.