Alternator wire / Alternator problem

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kelv

Alternator wire / Alternator problem

Post by kelv » Mon Jul 27, 2009 8:54 pm

There is a wire coming off a small conector at the side of my alternator.
This travels up into the Bongo, and behind the dash.
The charging and sediment lights do not appear at all if this wire is left disconnected.
When the wire is put to earth, the charging and sediment light come on at ignition and do not go off.
The battery is gong flat.
Am I correct in thinking that the wire should be going to earth, and that the lights are on beause the alternator needs replacing.
Or, is there something I am missing ?
Thanks.
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Re: Alternator wire

Post by g8dhe » Mon Jul 27, 2009 9:43 pm

The wire comes from the Alternator electronics and sends out an earth to the two lamps on the dashboard (via diodes) hence why both lamps come on when there is an alternator problem. If you would like to see the diagram shout and I'll put them up tomorrow.
Geoff
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kelv

Re: Alternator wire

Post by kelv » Mon Jul 27, 2009 9:52 pm

g8dhe wrote:The wire comes from the Alternator electronics and sends out an earth to the two lamps on the dashboard (via diodes) hence why both lamps come on when there is an alternator problem. If you would like to see the diagram shout and I'll put them up tomorrow.
Diagram would be very useful indeed thanks
kelv

Re: Alternator wire

Post by kelv » Mon Jul 27, 2009 9:53 pm

Why does the earth wire go behind the dashboard and pick up an earth ? ( my one goes in that direction anyway).
I got the lamps on by just putting it to earth so could it go to any close earth on the body etc ?
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Re: Alternator wire

Post by g8dhe » Mon Jul 27, 2009 10:28 pm

No the alternator sends out an earth on that wire presumably under fault conditions to light the lamps up. Normally I would expect that wire to be at +12v or floating if disconnected from the lamps. I'll put the diagrams up shortly.
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Re: Alternator wire

Post by g8dhe » Mon Jul 27, 2009 10:49 pm

OK two diagrams one for the Alternator and Starter and the other for part of the Dashboard which includes the Charge and Sediment lamps. The link between the diagrams is on connector 3.
ImageImage

In operation I would expect that the alternator, if working OK would send out either +12v or disconnect the wire. But under fault conditions it will earth it which will then turn on both lamps together.

Click the thumbnails for full size diagrams (or right click and open in new Tab/Window if you prefer).
Geoff
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kelv

Re: Alternator wire

Post by kelv » Mon Jul 27, 2009 11:07 pm

Thanks.
I can't read the diagram very acuratly sorry, ( thick)
Does the earth wire from the alternator attach to a black and red wire in the loom behind the dash ?
That's where I have connected my alternator wire which has resulted in the lamps coming on,there were no lamps on before, presumably because the earth was not being sent.
Does that sound right ?
:?
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Re: Alternator wire

Post by g8dhe » Tue Jul 28, 2009 12:09 am

Its not an Earth wire coming from the alternator, its a signal wire, which is connected to earth if there is a fault by the electronics, or is connected either to +12v or not to anything at all, when its working OK.
The wiring colours are always a bit of a guess its marked as being L/O which might mean Light Orange or something totally different :?
If you have connected an earth to the wire without disconnecting it from the alternator then you might possibly do some damage ( not possible to be sure as the electronics in the box is not shown!), as a general rule its better to disconnect things and measure the voltage first before connecting unknown wires to any other point :!: :roll: However alternators are generally built on a rugged scale so I would not get to worried :)
Geoff
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Re: Alternator wire

Post by madmile » Tue Jul 28, 2009 12:12 am

Is this an original wire or one that looks recently added?
A few people have tried usingthe 'no charge' indicator as a relay signal for a split charge relay.
When used, this additional load seems to cause the charge and sediment lights to glow slightly.
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Re: Alternator wire

Post by Yamaha » Tue Jul 28, 2009 12:59 am

Geoff - the way I've always understood the ignition light works is by having a live feed to one side of the lamp when the ignition is switched on. The other side of the lamp is earthed through the alternator when at rest. As soon as the alternator energizes, the wire becomes positive - so the lamp has positive on both sides, therefore extinguishing.

I have successfully used the charging light circuit wire to switch the split-charge relay by using a transistor in circuit to switch the relay - thereby only putting about a 125mA load on the charging circuit. Works well.

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Re: Alternator wire

Post by g8dhe » Tue Jul 28, 2009 10:25 am

The trouble is there are several different methods used these days, at one time the Charge light was actually part of the exciter circuit but these days most are fed via logic and are nothing more than fault indicators, you can only assume that if its high or open circuit then the alternator thinks things are happy. There is a bit more detail on Toyota circuit here. I don't have any more info as to what's in a Bongo alternator.
Geoff
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kelv

Re: Alternator wire

Post by kelv » Tue Jul 28, 2009 3:18 pm

Thanks for the helps guys.

I have now changed the alternator, which was certified faulty by Nippon in Bham ( New one cost £138 )
I have also changed the split charge relay for a more robust unit and had the system checked by an auto electrician.
The random wire out the side of the alternator was part of an old split charge relay presumably, and has been chopped.

All is now well.

Could be worth noting that if you rcharge light disappears altogether, it could mean the alternator is faulty, just as if they stay on it does.
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Re: Alternator wire

Post by francophile1947 » Tue Jul 28, 2009 3:48 pm

Oh well, it's a result - just a pity it wasn't a cheaper one :roll:
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kelv

Re: Alternator wire

Post by kelv » Tue Jul 28, 2009 4:00 pm

Alternator looked like the original one, probably not bad for a 12 year old part.
Nippon were £50 cheaper than the coventry place and Bongo bits, so worth shopping around.

Now only got to sort out the brakes and the aircon, and the width :lol:
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Re: Alternator wire

Post by Hippotastic » Tue Jul 28, 2009 5:19 pm

kelv wrote:Thanks for the helps guys.

I have now changed the alternator, which was certified faulty by Nippon in Bham ( New one cost £138 )
I have also changed the split charge relay for a more robust unit and had the system checked by an auto electrician.
The random wire out the side of the alternator was part of an old split charge relay presumably, and has been chopped.

All is now well.

Could be worth noting that if you rcharge light disappears altogether, it could mean the alternator is faulty, just as if they stay on it does.
I might have the same issue as you, my batteries are not being charged.

Bongobits want £135 inc for an alternator, I guess with P&P on top.

Where is Nippon in b'ham?
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