Electrical problem 940

[Laird Scooby]

Originally Posted by Ammorack

That blue lead from the alternator. That grounding there. I have cleaned where the lead contact the block.

RENEW THAT LEAD!!!!!!!

Seriously, the lead fries itself where you can't see it, the only cure is to renew it, cleaning the ends won't make any difference!

[Laird Scooby]

Originally Posted by Ammorack

I’m here to find help and support. And hopefully someone is kind enough to do so. Not to be harassed.

We're trying to help and support you but when you blatantly ignore our advice and suggestions, it's understandable we get a bit upset.

Ash is a highly qualified auto-electrician, as am i and if both of us are suggesting the same thing then it's a fair bet that's likely to be where the fault is.

If you can't renew that short earth strap between the engine and the alternator then seriously take it to a local auto-electrician and report a charging fault - NOTHING ELSE!

They will find it from there!

[aardvarkash10]

Originally Posted by Ammorack

That blue lead from the alternator. That grounding there. I have cleaned where the lead contact the block.

I have had this issue for some months now, and I can’t find the solution.

It feels like the alternator charge after 3000rpm and under that it almost stalls

The symptoms you describe are inconsistent.

You obviously have not checked for a voltage drop as Dave advised.

You are making random guesses as to the cause.

You have been attempting to fix the problem for 90 days and still have not.

When advised to seek local assistance, you discard that advice. This is the second piece of advice you have been given and not acted on.

All these are indications that assistance by remote control is unlikely to work.

What you see in the outline I have written is a process of diagnosis. You should try that.

[Laird Scooby]

Originally Posted by aardvarkash10

The symptoms you describe are inconsistent.

You obviously have not checked for a voltage drop as Dave advised.

You are making random guesses as to the cause.

You have been attempting to fix the problem for 90 days and still have not.

When advised to seek local assistance, you discard that advice. This is the second piece of advice you have been given and not acted on.

All these are indications that assistance by remote control is unlikely to work.

What you see in the outline I have written is a process of diagnosis. You should try that.

Those symptoms are consistent with a failed earth strap Ash, the voltage reg can't put a decent current through the rotor to exicte it below 3000rpm but it still puts the charge warning light out, especially above 3000rpm as it will self-excite through residual magnetism in the rotor..
Because it can't output all the current it produces because of the duff earth strap, when the revs drop below 3000rpm it basically back-feeds itself and stops charging again.
Sadly we have no idea exactly what load is being pulled when he's dropping that 0.15V somewhere (possibly 0.55V if the reg is cold and should be putting out 14.4V) so it's difficult to make a guess at what resistance is being generated on that link but the resistance will go up as more current goes through because it will get hot.

I know you already know all this - just letting a bit off if you catch my drift.

[940volvoman]

As previously discussed at length in another thread here, I added several additional cables which, together with experts on here, seem to have solved my similar issues:
I bought and fitted a Halfords ready made earth lead from the battery negative to the car chassis. I bought and fitted a Halfords ready made positive lead from the battery to the alternator main + terminal, (and sleeved it), and fitted an additional ground lead from the alternator to the alternator grounding point on the engine, together with an additional ready made Halfords earth lead from the alternator - ve terminal to the same earth terminal on the chassis as the battery. All terminals were cleaned. Together with a replacement voltage regulator and the difference is like night and day....
My existing wiring loom was not replaced, just added to.

[aardvarkash10]

Originally Posted by Laird Scooby

Those symptoms are consistent with a failed earth strap Ash,

bits of it are, yes.

Originally Posted by Laird Scooby

the voltage reg can't put a decent current through the rotor to exicte it below 3000rpm but it still puts the charge warning light out, especially above 3000rpm as it will self-excite through residual magnetism in the rotor..

If you cant get a field excitation current through the earth strap, it will be OBVIOUSLY toast! Output current (if you can get self-exiciting) will be near zero as well and there is no way the battery would maintain a charge either.

Originally Posted by Laird Scooby

Because it can't output all the current it produces because of the duff earth strap, when the revs drop below 3000rpm it basically back-feeds itself and stops charging again.

Once the alternator has excitation and is producing a voltage, the internal field circuit (which is independant of the rest of the vehicle earthing) will be maintained regardless of engine speed. In other words, the alternator will be producing a voltage and supplying its internal needs and regulating to that (its machine sensed after all...), but not a current to the battery because of he toasted earth strap.

Thats where the "below 3,000rpm" bit doesn't make sense if hte fault is ONLY the earth strap. I expect there are at least two problems.

Originally Posted by Laird Scooby

I know you already know all this - just letting a bit off if you catch my drift.

Back at ya!

On a separate issue, stay safe folks - I'm currently trying to figure out how many of 800 staff I still have jobs for... My advice is isolate, and drink only good whiskey.

[Laird Scooby]

Originally Posted by Ammorack

Alternator regulator are new.

Originally Posted by aardvarkash10

Thats where the "below 3,000rpm" bit doesn't make sense if hte fault is ONLY the earth strap. I expect there are at least two problems.

My suspicion is he fried the original alternator and the new one is on its way because of the earth strap. Assuming (dangerous i know) the original fault was simply not charging due to the earth strap and it killing his original alternator, the new one is behaving as i would expect but as you suggest Ash, there could be a second fault which won't show up until the earth strap is fixed.

I'm wondering if the classic mistake has been made of connecting the warning light wire to the "W" terminal.

Either way, we won't have any progress unless and until that alternator earth strap is renewed as any test results will be nonsense.

[TonyS9]

Do you have a multi-meter?

[Ammorack]

Originally Posted by Laird Scooby

We're trying to help and support you but when you blatantly ignore our advice and suggestions, it's understandable we get a bit upset.

Ash is a highly qualified auto-electrician, as am i and if both of us are suggesting the same thing then it's a fair bet that's likely to be where the fault is.

If you can't renew that short earth strap between the engine and the alternator then seriously take it to a local auto-electrician and report a charging fault - NOTHING ELSE!

They will find it from there!

Wow didn’t expect this to blow up. Thanks for helping me out. I’ll do what you guys told me now. And I’ll keep you guys updated.

[nutco]

Originally Posted by Ammorack

Wow didn’t expect this to blow up. Thanks for helping me out. I’ll do what you guys told me now. And I’ll keep you guys updated.

Thats what its like on here sometimes, every one means well tho