Alternator wiring query / fault ? MK III 1.7 TD LS (GM block)

[guymark]

Hi.

I have just had my van head gasket sorted and a new pump / cam belt fitted to boot - so far all good.

When the van came back, the fellow said he had to jump start it as the battery (new) was flat. He reckoned when running voltage down to under 11v - and indeed it is. (Battery since re-charged and holding charge fine)

Before the van went in, it was working fine - now not only does it not charge but curiously I no longer have an alternator warning light (I'm fairly sure I did before).

On the back of the alternator - a Delco Remy CA516IR - there is the big stud for the red wire, (which also has a black wire which goes to the the regulator connected here) and two more studs. One which I am sure USED to be used as it has a clean shiny bit part way down the stud - and another one which currently has the blue wire connected to it - with a lucar spaded green wire floating about.

A few questions:-

1) Is the green wire unused (I know this does sometimes happen on looms) - and if not, where does it go - as I cannot see a space connector on the back of the alternator.

2) Of the two studs (other than the big one), which should carry the ring ended blue wire please?

3) If he has indeed used the wrong stud, is this likely to have killed the alternator.

4) On the blue wire, there is a voltage (with key off) of around 7.3v which I am guessing is supposed to be going to the field coil. What limits this voltage from 13v to 7v - as it is not the resistance of the field coil as the voltage was measured with the lead coupler disconnected.

If someone happens to have this alternator and has 5 mins to spare to have a gawp and see which wire goes to which of the thin terminals I would really appreciate it.

Lastly, if the alternator has indeed popped clogs, what is a decent cheapo replacement (new) - there are no extra lights or sound system. Totally bog standard

Thanks a lot to anyone who can spare time to give a bit of info. I have tried several times to take photos but they are no clear enough to help - hence long winded description.


Blue Skies
Mark

 

[ega-estate]

had a quick look and on the top connection is a big red wire ring terminal, another two wires blue/brown and green go into a plastic plug. cant see where those wire go as my alto is covered with a plastic casing. sorry i cant be of any more help

 

[paul.spencer]

Hi Mark,
I rebuilt my alternator (same as yours) a year or so ago and took pictures along the way but it was pretty dirty so not sure if you can see what's what. I'l take a look through them and see if there's one to answer some of your questions...
Cheers, Paul

see if this works - Delco Remy after a bit of a cleanup

 

[guymark]

Thanks very much Ega & Paul.

If it has died a death I shall probably have a go at just refitting one myself - but didn't want to remove the thing if it is just a case of poking some wires in different places!

Of the two smaller posts, one seems to have a big round plastic base and the other doesn't - but is nearer the chunky post for the red wire. Very rare that google cannot help but haven't been able to find a pic at all of the back of one of these things - just "equivalents" with very different back layouts.

Anyway, thanks again to you both and if your pics offer any thoughts Paul, would really like to hear your findings.

Kind Regards
Mark

 

[paul.spencer]

A few questions:-

1) Is the green wire unused (I know this does sometimes happen on looms) - and if not, where does it go - as I cannot see a space connector on the back of the alternator.

2) Of the two studs (other than the big one), which should carry the ring ended blue wire please?

3) If he has indeed used the wrong stud, is this likely to have killed the alternator.

4) On the blue wire, there is a voltage (with key off) of around 7.3v which I am guessing is supposed to be going to the field coil. What limits this voltage from 13v to 7v - as it is not the resistance of the field coil as the voltage was measured with the lead coupler disconnected.

thought I should try to answer a couple of your questions

1) If I'm not mistaken the green wire is for the rev counter and I think should be connected to the inner small post.

2) IIRC mine has a blue/white wire and it looks like its connected to the outer of the small posts.

3) I don't know what damage if any would be done if the blue (or blue/white) wire was connected to the wrong post - possibly no damage as the wrong post might only be rev counter signal

4) haven't a clue about this - I'll go put a meter on mine and report back later...

 

[guymark]

Thank you for all your effort Paul, I really appreciate it.

I don't have a tachometer on mine, so unless the ECU (is there one?) needs the signal, I am guessing it is perhaps "spare" - certainly seems just fine without it.

Yep mine is also on the outer of the studs - just puzzled as the other stud has a very clean/shiny bit as if something WAS there until recently.

It may just be that the unit is as dead-as-flares in which case I will have to buy a new one - just seems a bit of a coincidence that it died after it has been at the mechanics for a few days with head off. I have found a company called Hillmar which are offering a new one for £69 +4.95 carriage so I guess if I DIY, the worst case scenario isn't too horrible! I am considering a local scrapyard but if I buy a second hand one for £30 and it goes belly-up in a few months time I will kick myself

Again, thanks very much for helping me with your findings - also only just spotted the photo above. that is the same as my one and it is the innermost stud of the three on mine which has no wire going to it (as the wire ends in a spade connector). It looks as though that means the wires are going where they should - in which case I suspect it has died.

Kind Regards
Mark

 

[paul.spencer]

hey I meant to ask whether you had put a meter on your battery terminals when the engine is idling - it should read 14 volts or thereabouts. If not then the alternator isn't charging the battery....

 

[guymark]

Nope, the alternator is not charging - If it was charging I would be a happy bunny. I just was trying to work out why it might not be charging.

I know it is not some humping great fuse from the alternator as with engine on or off, I get the same reading on the battery + as I do on the alternator + - so at least there is continuity there.

Then I have a dissused green wire (might be green/black hard to see) and the blue wire which has seen better days but is still intact according to the meter

One thing that I wondered was the battery warning light (which doesn't work now) on some cars is also how the field coil is woken up. This presumably is the blue wire which I find 7.3 volts on with the ignition OFF. Alas when the engine is running, this goes to whatever voltage the battery is at (care of battery charger) - eg: 12.9 earlier on when battery still charging so whether through a bleeder resistor over the bulb or some other way, the field coil is at least offered some power I think.

I might try and see if I can get to the charge warning light tomorrow to see if it has blown - most of the dash bulbs have but they were gone when I bought the van - I just didn't really have "dash removal" on my list of Sunday pleasures!

As someone naughty once said, if it has Wheels or Ti*s it'll cause you hassle in the end

Have fun

Mark

 

[paul.spencer]

blue/white wire on mine reads 0 volts with ignition off.

don't know why yours would read 7.3 volts but doesn't sound right...

 

[guymark]

Your a grand fellow - thank you for going and testing that for me.

Agreed. It does sound strange. I am going to see if I can find a wiring diagram and see where the wire goes en-route to the dashboard charge light - and where the charge light gets a feed from. If I can find the feed, I might be able to test the bulb without dismantling the dashboard - it would be a bit galling to pull it all to bits only to find the bulb was alive and well - but not being given any power for another reason.

I guess bottom line is probably to apply 12v direct to the field coil on the alternator and see if it makes it work - if so - just stick a feed via a 10w bulb and a push button in the short term. If it DOESN'T generate when the field coil is powered then I am guessing it has died and needs replacing - irrespective of why the charge light has died too.

Again thanks for getting the meter out and going to check on your car, that certainly helps to confirm something is definately not quite right on mine.

Mark

 

[guymark]

Just to close this one off. I found the solution today.

The shiny stud was somehow a red herring - why it stayed shiny I know not.

The problem was that despite the humping great bolts fastening the alternator to the engine, because of the rubber bushings, it is vital that the earth strap is in place - which it was.

However the strap had been put back on all oily and amazingly failed to make contact with the engine frame at all. The alternator was not grounded at all. There was this huge block of metal completely isolated from the rest of the engine electrically.

Plonking a length of copper from engine to alternator body immediately made everything come alive - engine warning light works again when engine off and ignition on.

I knew this sort of thing could happen in theory, but never seen it actually happen in practice.

Tomorrow I will do some bolt removing, contact cleaning and replacing - lost the daylight today.

Mark

 

[paul.spencer]

well spotted - thanks for the update...

 

[ega-estate]

yeah nice one, glad its sorted and alot cheeper that a new alto!