Alternator

[rustic]

Ok connected said bulb, +12v from battery one side and excitation terminal the other

IGN Off = bulb lit

Ign on = bulb lit

Eng on (battery is pretty flat) = Bulb on BUT voltage across battery raises to 13.5v

Ign Off / Ign on in your configuration will mean bulb lit.

If the engine is running and rising to 13.5 Volts then it is probably charging, but the lamp should have gone out straight away, provided that you are connected to the excitation terminal.
Check the voltage say when you put the headlamps on, it may go down slightly.

Seems to point to an Alternator fault (regulator) to me.

Now with the later alternators is the voltage regulator part of the Alternator?
if seperate from the alternator then this could be the problem.

The alternators I have looked at have had the regulator as part of the alternator.

 

[rustic]

Looking at the manual the regulator is part of the alternator, so it does point to a faulty alternator or a bad or wrong connection at the alternator.

 

[ShaunAFC]

I see where you are going, but what is causing the second voltage on the panel?

Even with alternator disconnected - excitation wise - I still get those 2 identical voltages either side of the bulb connector.

Thoroughly confused right now

 

[rustic]

I see where you are going, but what is causing the second voltage on the panel?

Even with alternator disconnected - excitation wise - I still get those 2 identical voltages either side of the bulb connector.

Thoroughly confused right now

I just looked at the circuit diagram, is yours an Automatic as there is a back feed from another switch ? this will cause a back voltage also there is
a small resistor across the bulb as well this will feed 12 volts on to the other side.
I assume you are using a digital Voltmeter these have high impeadances and draw very little current, and show voltages even through resistors so caution with these readings. Sometimes the old Avos are better.

I will be off line for a while I will re-look at the diagram later.
Still looks like the alternator to me..

 

[ShaunAFC]

It is indeed an auto.

 

[ShaunAFC]

It is indeed an auto, and yes I am using a multimeter.

I have just checked and get this:



Red arrow has +12v all the time, ign or not

Yellow arrow doesn't show a voltage at all, ign or not.

Now, when I had the lamp on I had it connected to the yellow arrows terminal on the alternator.

 

[rustic]

Apart from earth then is this the only connector on the alternator?
We are dealing with the 2.7 tdi model, not the 3 litre.

If this is the case then:
The top heavy cable in the connector should be the battery feed. Hence 12 Volts
The other should be 12 volts with the ignition on only as far as I am aware.
BUT this is not as simple as the 2.7 TD version.

There is a 10 Amp fuse that feeds this part of the circuit No 12 according to the schematic, have you lost any other indicators?

What a stinker,
In the manual, Page EL 81 it shows power coming through the diode, the ignition warning light ( charge light on the schematic) looks like an LED ( Light emitting diode) with it's curent limiting resistor. There are 2 resistors going around the LED that will be supplying most of the power for the field coil thus giving 12 volts to the alternator on the excitation connector.
You have checked and there is 12 volts on the ignition lamp(LED) but not at the alternator, has the wire at the connector at the alternator broken?

 

[ShaunAFC]

Hi,

It is the 2.7TDi.

Have checked the fuse and all is good in that respect.

It has the following:

Earth, down to chassis
Big mutha of a red cable, this literally bolts on and I assume is the main charge path back to the battery.
I then have the connector pictured which plugs in to the alternator, on the red arrow side it has a permanent 12v, on the yellow arrow side it displays a permanent 0v. (by permanent I mean IGN on / IGN off Engine on or off)

Think my next test is continuity from yellow arrowed connector to dash.

 

[ShaunAFC]

Ok, just did the continuity test and I have from the yellow arrow connector to right side of the bulb 0.02 ohms from the same point to the left side of the bulb is about 9 ohms

Also I am now getting 12v switched from the ignition on this connector.

So it now has on this one connector 12v permanent and 12v switched from battery.

Only thing I have done differently is plugged the S (sport) and * (snow) switch in and the door lock one.

dont understand why it has a switched 12v and a permanent 12v on one connector??

 

[rustic]

I don't know why you have 2 wires on it anyway, must be something else?

I hope others on the site can advise.
The electronic manual doesn't seem to shed any light on this one.

Have I missed something?

 

[ShaunAFC]

If anyone on this site could do me the biggest favour and take the plug from their working alternator and tell me what voltage values they get on each socket on the plug, I would be most grateful!!

 

[ShaunAFC]

Ok, have been studying and it seems that:

One terminal should go to earth - check
One terminal should come from the battery 12v - check
One terminal should be from the IGN - check
One terminal is the feed to the battery - check.

I wonder if I have a loose connection on the ign wire and that is why I only got ign voltage second time of testing!

 

[rustic]

Am I the only member able to help Shaun, other than Timbo?

Ok, have been studying and it seems that:

One terminal should go to earth - check
One terminal should come from the battery 12v - check
One terminal should be from the IGN - check
One terminal is the feed to the battery - check.

I wonder if I have a loose connection on the ign wire and that is why I only got ign voltage second time of testing!

Hi Shaun, this does seem to be the area to check, Is the new alternator showing the same problem as your original?


Am I the only member other than Timbo, on site to help Shaun on this one? :nenau

I knew a bit about the older alternators.
OK about 15 years ago I helped to design the electrical side of an Alternator tester, switched loads, digital and voltage monitoring etc. Some with regulators on board others seperate, but I have never looked at this type before.
So has any body got any other ideas, to me it looks like a wiring fault on the vehicle, but who knows?


Best regards,
Rustic

 

[ShaunAFC]

One more throw of the dice tomorrow, then its going to an auto elec.

Thanks for all the help, I do appreciate it.

 

[rustic]

One more throw of the dice tomorrow, then its going to an auto elec.

Thanks for all the help, I do appreciate it.

No probs, good luck.
best regards,
Richard
(Rustic)

 

[rayf3262]

Looking at the manual in Start/Charge section pages sc-24 (TD27Ti) & sc-25 (ZD30).
From your description it appears you have the ZD30 style of alternator which has the additional battery feed on pin 4 of the connector. Pin3 (L) is the IND connection this should be connected via a small (2W) or similar bulb to the battery via the ign switch.

I would run a separate lamp from this terminal to the battery, it should light when the engine is stopped & when running (alternator charging) extinguish. This will at least eliminate any wiring issues with the ign/ind.

 

[ShaunAFC]

Been done further back fella.

Auto elec is out on Friday, so hopefully we shall see