Vauxhall Alternator on Series

[nitro_warrior]

I have fitted a "new" alternator to my lightweight with a 2.25 diesel engine. Previously it had a alty from a Nissan of some sort. But I wasn't having much luck finding one so have aquired and fitted a Vauxhall one from a 1.7D engine.

So everything is fitted and it looks ok but I can't work out what should plug to what. Previously there was only a positive and an earth.

The new alternator has 3 wires going to a multiconnector, green, black and yellow. And a screw terminal on the back.

With nothing connected I measured the voltage at each terminal and they all read 0V except one which reads about 0.5V.

I suspect it will need a battery connection to start charging but don't want to start plug stuff in in case i break it.

Here are some pictures I would appreciate any thoughts!







Single terminal on the back

[nitro_warrior]

Not had much time to look at it as I was at work today but I had a closer look at the terminal and sure enough it says BAT next to it.



The multiconnector doesn't have any markings on it and the three cables (green yellow and black) all look the same gauge. I don't know the vehicle but it's probably a vauxhall van not sure the age but there are a huge number of 1.7d vauxhall vans about. I do have a wiring diagram in an old Cavalier Haynes manual, doesn't seem quite right though.

[nitro_warrior]

Really appreciate your help Dennis. Starting to make a bit more sense!

The label's a bit tricky to get a look at with the alty installed but I managed to get my camera down the side and snap a couple of pictures to get the info.





Valeo
VA241
VP

Mean anything to you?

[nitro_warrior]

I've been doing a bit of research. I've heard from a few places the green lead is the output to the tachometer so I can probably discount that.

I was also told the wiring for a 1.7 Isuzu diesel which will probably be pretty similar as it's the same GM family was

[nitro_warrior]

The curious thing is the old alternator was only wired up with two leads.

So I connected the big cable from battery +ve to the screw terminal labeled BAT. And I connected the other lead, that goes from 0v to 12v when the ignition is on, to the black wire.

There's no tach, and the charge lamp wasn't wired in before.

But after starting it and revving it there was no voltage change on my multimeter. So does the charge light need to be connected for the alternator to start charging?

There is a spare lead nearby which might be the one for the charge light but it was getting dark and I had a bicycle to fix so I had to stop for the night!

Maybe I was too quick to assume the old alternator was faulty?

[nitro_warrior]

Well thanks once again for your advice! But I'm starting to think there may be something else that’s not quite right.

I followed your advice and checked the lead from the charge lamp and the light came on when it went to ground. Good.

The resistance on the Black and Green wire both showed a broken circuit and the yellow wire read 0.0 Ohms. As the advice I had got said the green is tacho and the black is excitation I plugged the lead from the charge lamp into the black lead.
(which is how it was wired last night)

With the ignition on the charge light came on, all good.

So I start it up and rev it a bit but the voltage across the battery stays the same ~12.5v and the charge light stays on. Then randomly it decides to work, the charge light goes of and the voltage jumps to ~13.5v. Good I think and play with the lights and rev it to see what the reading does then randomly it stops charging. Then just as randomly it starts charging again, and I leave it idling and the voltage slowly builds to 15.4v, I play with the throttle a bit then it stops again, and this time doesn’t start charging again, and i've not been able to get it charging again.

What would make it intermittent?
Is the there a regulator on the excitation charge light line that’s playing up? Or do I need to put the F–ve yellow terminal with 0.0 Ohms to ground? I was starting to wonder if 15.5v was getting a bit high for the alternator to outputing?

Donald

[blanche_90]

dont know, just a guess this is, wait for dennis to give you a proper answer, but it sounds to me like the dioed pack has packed up.

not much help to you i know, as when they get like that, i just get another, but in your case it's not so easy as it's not a like for like swop!
sorry

[nitro_warrior]

Thanks again, really appreciate your help. I'll get an opertunity to through this tomorrow.

As for it being coupled to the ECM module, I think the alternator is probably from a mid 1990s GM vauxhall. I wouldn't of thought an alternator from then would have been bothered by any control so advanced?!

As some further info i'm pretty sure it's like this one here.

http://www.vauxcentre.co.uk/index.php?product_id=707999&option=Prod_detail

[nitro_warrior]

Well I measured what I could, I don't know where the regulator bits are to measure.

However the voltage difference between the alty output and at the other end was only 0.1v and there is very little resistance between the casing and the body so the earth connection looks ok.

Again it started chaging when I started it this morning but stopped when I revved it and now refuses to charge.

I checked the wiring back to the charge bulb and it all seems fine goes to a brown wire with yellow tracer.

I also took a panel off the alternator where the wires go in but didn't help me, (not sure what I was hoping to find!) there are 2 screws and 2 big solder tabs.


I'm reluctant to try yet another alternator but can't see what else to do. Can anyone recomend an alternator with vacuum pump that should work and fit easily?

[nitro_warrior]

Well in my last blast of tinkering I decided to add a voltage regulator I ahd lying around to the charge light wire. It didn't work, and the voltage on the line drop to 4V so I took it off...

Also been thinking about what could be wrong, when I first connected it I put the charge light excitation wire on the output +ve terminal. Could I have broken the regulator doing that?

[nitro_warrior]

Time for an update.

I decided to set-up a bench test for a Nissan Serena alternator which I got orignally (It was huge and I would have needed a longer belt).
It seemed to work ok so i decided to try the original alternator (a smaller nissan one) that wasn't charging. Turns out I should have checked my brothers wiring more carefuly in the begining. It worked fine with the excitation line plugged in to the right socket...

Next i took the vauxhall unit off the land rover and tested it. It seemed to charge when running off a drill on a bench but, whereas the other alterators would put out a steady 14.5v or there abouts, the vauxhall unit put out about 15.7v and fluctuated alot with different drill speeds.

I concluded that the vauxhall alternator was knackered (probably from when i wired it backwards at the start), and refitted the original alternator, and wired it up correctly.

Hey presto it works! Moral of the story, check it's wired up right.

Nevermind, went for some celebratory off roading and it worked fine, and I didn't break anything so all is good with the world onece more!

[nitro_warrior]