Where does the output wire go from the alternator?

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Shotage
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Where does the output wire go from the alternator?

Post by Shotage »

Hi.

My Dad has just replaced brushes and electrode on my alternator as it had stopped charging. The alternator is definitely working now, but it's not charging the battery.

On inspection it seems there is a wire that should be going somewhere but isn't, it's the output apparently. Does anyone know where this goes or a wiring diagram for it please?

Many thanks,
Andy
1988 VW T25 Auto Sleeper
1.9 petrol / watercooled

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Shotage
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Re: Where does the output wire go from the alternator?

Post by Shotage »

Should have said it's a 1988 VW T25 1.9 petrol DG.

Thank you.
Andy
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Re: Where does the output wire go from the alternator?

Post by Oldiebut goodie »

I think you had better put up a pic so that we can see exactly what you have there otherwise we will have to ask numerous questions to build up a mental picture.
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Re: Where does the output wire go from the alternator?

Post by Shotage »

Thank you. The van is at my parent's house but will go there tomorrow morning and get a pic.

Andy
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Re: Where does the output wire go from the alternator?

Post by itchyfeet »

Late dg has a red wire from alt to the starter ( which in turn joins to the batt) and another red to the black box both from an m8 ring terminal on the alt.
There is also a small blue wire which is the charge light, it goes via the black box and fuse box to the dash, without it the alternator won't produce the approx 14v
What volts do you have with engine running on the alt main terminal and on batt?
If you dont get the approx 14v try revving the engine to 3k revs and see if it starts making the voltage?

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Last edited by itchyfeet on 15 Oct 2014, 20:14, edited 1 time in total.
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Re: Where does the output wire go from the alternator?

Post by Oldiebut goodie »

I was trying to avoid the guessing games!
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Re: Where does the output wire go from the alternator?

Post by itchyfeet »

Oldiebut goodie wrote:I was trying to avoid the guessing games!

:D back to your old self then :ok
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Re: Where does the output wire go from the alternator?

Post by Oldiebut goodie »

We all know that there are numerous previous bodges in the last 20+ years so telling a 'new to him' van owner to put the red/black/whatever wire to y point could lead to disaster which I was trying to avoid. I know that some wires in my engine bay don't correspond to the original vw colours like a lot of others.
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Re: Where does the output wire go from the alternator?

Post by CovKid »

As Itchyfeet says, on some years, that wire goes over into the black box on the left in engine bay, then on to starter.

http://wiki.club8090.co.uk/index.php/VW ... ain_cables" onclick="window.open(this.href);return false;

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Re: Where does the output wire go from the alternator?

Post by Shotage »

Thank you very much. Going to pass this info on to my Dad and go and have a look myself. Fingers crossed we can get the old girl going again :-)

Andy
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Re: Where does the output wire go from the alternator?

Post by Shotage »

Guys, please can you help again?

This is all a bit above my head, but my Dad would like to know where does the red cable go after the black box? Apparently this is somehow drawing 30amps! If we can find out where it goes after the black box maybe we can fix the problem.

Thank you.
Andy
1988 VW T25 Auto Sleeper
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Re: Where does the output wire go from the alternator?

Post by Oldiebut goodie »

It should go to the battery. Do you mean it is drawing 30A with the engine running or without? With the engine running it will be the normal charging from the alternator to a somewhat discharged battery or some other high current drain. Without the engine running - something or several things are switched on taking high current.
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Re: Where does the output wire go from the alternator?

Post by itchyfeet »

In my 88 DG pic above and below the smaller red from alt to the black box is used to power the engine manifold and carb heaters only via a relay, it does not connect from the black box to the starter or battery. Try pulling the relay out of the socket in the black box.

The second larger red from the alt goes to the starter motor.

As said your wiring may have been changed over the years so pictures will say a lot.

There is loads of space around these engines, just follow the wires between alt black box and starter.

These cables are not fused and connect even when engine is off so if you have concern about a short or heavy current draw disconnect the battery when you leave it, you don't want a fire.

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Re: Where does the output wire go from the alternator?

Post by Oldiebut goodie »

That's the trouble - no one can be sure without seeing. I doubt that there are many vans with completely original wiring. 30A draw is one heck of a lot if the engine isn't running!
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Re: Where does the output wire go from the alternator?

Post by Shotage »

I haven't been able to get round there today. 30amps draw when running I believe.

Will catch up with my Dad tomorrow and see where we're at and take photos too.

Thanks very much for all of your help, I really appreciate it.

Andy
1988 VW T25 Auto Sleeper
1.9 petrol / watercooled

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