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Technical 2004 Scudo 2.0 JTD SX Battery light on.

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Technical 2004 Scudo 2.0 JTD SX Battery light on.

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Zog

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Battery light suddenly came on. I know little of these things.


The alternator seems to be turning.

A multimeter across the battery terminals show no effect from increasing revs.

I can't see, at a cursory examination, loose wires.


I took the connections off the top of the alternator (two eye connectors in a sandwich) and they loook clean.

There's another connector but I can't work out how to undo it... a press-on connector with one wire going up a ribbed duct, and a little green stub thing that looks like another wire broken off, but I don't think is, it seems springy, has that got something to do with how to get the plug off?.


Batter voltage (disconnected) id about 12.6v.


Any useful diagnostics possible?

I'd like to find out if the alternator's shot before just replacing it, I'm on my uppers.
 
Zog said:
Battery light suddenly came on. I know little of these things.


The alternator seems to be turning.

A multimeter across the battery terminals show no effect from increasing revs.

I can't see, at a cursory examination, loose wires.
Click to expand...

Hi .
Battery should tead 12 volts . You have that

With engine running.. the alternator should be pushing out 14v

the battery terminals should show 14v ;)

Main things that happen

Brushes wear out.. so no connection.. no power

Or a wiring fault

Check the wiring 1st..
A photo would help :)
 
Oh, hi again, still here I see.... :) photo of anything in particular? I will go out & grab some.

I was thinking about getting the alternator off, but no idea about de-tensioning/tensioning the belt....
 
Well, that's sussed the little connector, anywhay, whatever it's for. The is a leg on one side that pushes back with a screwdriver from inserted from the right as you look with your head jammed under the bonnet.

https://imgur.com/a/mE4qfkf

The battery voltage does NOT increaase when everything's connected up and a multimeter is applied across the terminals with the engine running.
 
Last edited:
Some rvoltages, engine running...

Battery +ve to big terminal on alternator.... 0.02V.
Battery -ve to alternator casing.... 0.01V.
 
Ok, How about these thoughts for your consideration.

Battery voltage at this time is good and the car starts on the key - good starting point.

The battery light dashboard display is lit up. On older cars - so I think this is how your's will be working - when you turn the ignition key on there is a battery feed wire from the ign switch to the dashboard light and then on to the field excitation wires in the alternator then to earth and so completing the circuit to the battery. When the alternator starts to charge it "balances out" (simplified explanation) the current coming to it through the dashboard light and so the light goes out. As your light is lit up I think it likely this circuit is doing exactly what it should but the alternator is not generating current which is why the light doesn't go out. Worth noticing that with this setup if the dashboard bulb burns out - goes open circuit - you're alternator stops charging because there is no supply to the field in the alternator!

Now it gets more difficult with me not being able to test the car itself, so some educated guessing has to be made. The simplest thing to check is the main charging lead from the alternator to the battery. A visual check should show up any problems and check for loose connections and corroded wires. If you have a voltmeter you can hold one end on the alternator output terminal and the other end on the battery Positive. If the connecting wire is good you should see next to nothing on the meter. If all this checks out I think it likely you've got diode problems in the alternator. Watch out when probing, you could cause a spectacular short circuit!
 
Pugglt Auld Jock said:
If you have a voltmeter you can hold one end on the alternator output terminal and the other end on the battery Positive. If the connecting wire is good you should see next to nothing on the meter. If all this checks out I think it likely you've got diode problems in the alternator. Watch out when probing, you could cause a spectacular short circuit!
Click to expand...

I see

Battery +ve to big terminal on alternator.... 0.02V.
Battery -ve to alternator casing.... 0.01V.

I wish it wasn't so awkward getting at the wretched thing, Morris Minors are much easier.
 
Zog said:
I see

Battery +ve to big terminal on alternator.... 0.02V.
Battery -ve to alternator casing.... 0.01V.

I wish it wasn't so awkward getting at the wretched thing, Morris Minors are much easier.
Click to expand...
This test is what's called a voltage drop test. If the connections and main wire are in good condition then they will form the lowest path of resistance so current/voltage should flow through the wire and not the relatively high resistance which is the voltmeter (never do it with the meter set to amps!) I probably should have said to do it with the engine running for best results as there will be virtually no current flowing/attempting to flow if the alternator is not turning. if your readings are then still very low it would be saying your connections and the cable are in good order.

Because the car starts Ok the earth leads and connections would seem to be Ok too. (the earth return from the alternator is through the metal of the engine to the same earth lead that goes back to the battery.)

I think it very likely you have an internal alternator problem, most likely to do with diodes. If you know someone with an oscilloscope or good quality diagnostic equipment you can display the alternator output as a graph and see immediately if this is the problem without having to dismantle anything.

Oh yes, I'd like to go back to the simple life too. Morris Minor, my old Mk1 Cortina, or even a Hillman Imp would be preferable. Not so nice to drive though. By the way, I haven't looked at your pictures because I don't like to click on links unless I absolutely have to. Perhaps Charlie will see something in the pictures?
 
Pugglt Auld Jock said:
I think it very likely you have an internal alternator problem
Click to expand...

That's what I'm thinking (might be brushes, if these things have brushes, 'cos the van's done 250k+). I'll have to get under it & see if I can work out how to get the alternator off.

Edit: Those voltages were obtained with the engine running.
 
I think all alternators have brushes - haven't come across one without yet. Mind you I've never taken a really modern one to pieces and probably won't because the Factors will refuse to exchange it if they see/suspect it's been dismantled. You may find at the sort of mileages you're mentioning there that the slip rings (alternators don't have segmented commutators like dynamos) are deeply grooved and that renewing just the brushes will be a short term "cure".

In my old age and with the advantages of hindsight I would just go for a service exchange/rebuilt unit if the car is a daily driver where reliability is important. On an older "toy" I would enjoy dismantling and "fettling" it.

Do please let us know how it all turns out won't you? and good luck.
 
Well, I goth the alternator off, which wasn't too bad:

https://www.fiatforum.com/scudo/486311-removing-alternator-2004-2-0-jtd-sx.html

I had a look at the innards of the alternator.

Remove the black plastic cover (3 small bolts).
Remove the controller/brush assemply (3 small nuts).

Pull, jiggle, work off the controller/brush unit.


I saw that the brushes barely protuded at all from their housing:


https://imgur.com/a/y8AREWj


One of the slip rings was black, and rather worn:

https://imgur.com/a/uY2G3Gj


The face of the corresponding brush was black and covered in carbon particles (you can see bright marks where I touched the face of the brush with the end of a screwdriver, and the end of my finger smeared with black dust):

https://imgur.com/a/OD5Je7w


So despite that slip[ ring being very worn, I'm going to buy another brush pack/controller and bolt the whole thing back together & see if it fixes it... my guess is that is the problem.

It looks to me as though to re-fit the new component, which will have longer brushes sticking out, the brushes need to be pushed back into their housings, and the plastic cover pulling back, to stop the brushes from springing back out, then the component is bolted on, then the plastic cover is pushed back down, letting the brushes spring out and press onto the slip rings.
 
Last edited:
Yep

Worn out brushes always sounded likely

You can buy just the brushes..
But there may well be enough braidrd cable left .. that you can unsolder and let another 5mm of brush through..then resolder

I did this on my old FIAT td

Did another few years of running around
 
varesecrazy said:
You can buy just the brushes..
But there may well be enough braidrd cable left .. that you can unsolder and let another 5mm of brush through..then resolder
Click to expand...
Nice!

There's a video here: https://www.youtube.com/watch?v=aVvPzwtxdrM

which is pretty good. Same bloke does "how to change the slip rings". Brushes are abour £3 (ebay, online motor factors cheaper but postage seems exorbitant making total more).
 
I bought a pair of brushes (eBay, £2.79).

The braided leads to the brushes are thinner than on the originals. I hope that won't b a problem, but I might get another pair with thicker leads anyway. I guess these alternators can throw out a lot of current! Any comment?

Refitting the auxiliary belt is a bit of a pain. I did it from the top, and eventually used a 2'/600mm piece of batten to stop the belt slipping sideways off the back (engine) pulley while I manipulated the belt ont the other pulleys.

Another short piece of batten was useful to jam between the end of the socket handle on the tensioning pulley and the metal part of the front of the van near where the headlamp is to keep the tension off the belt. Mind your fingers!

The battery light no longer shows, so I assume this was in fact the problem.
 
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