weird problem

[ghost123uk]

Yep, re reading this, the basic over the counter multimeters cannot handle that sort of power , most are 10amps max
You sure it's not 4.5amps you are reading ?

+ 1 on that ^^^

What sort of meter are you using?

[OLD ONE]

Hi all .... Jeff and Boxy ..I am using an auto ammeter, that is normal dash mounted, on heavy wire and crock clips. A bit crude I know, but I know that my little multimeter would not be up to it

Steve...I know I am getting on a bit, but I feel sure I know where a decimal point fits in

Note heading of this post...Now even more weird.

[MGP]

I assumed the alternator before as it's the only thing that I can think of that has heavy enough wiring to carry 45 amps without melting something.
I would have thought that anything pulling that sort of power would generate enough heat that it wouldn't be hard to find.
Have you done anything with your ammeter to check it's accuracy?

Sent from my SM-G920F using Tapatalk

[ghost123uk]

Tis worth noting, as you point out, that a blown diode in the alternator can do this. I had it once on our scirocco. It didn't do it all the time, it depends on where the alternator "stops" when turning the motor off.

Sent from the pub.

[Smiffo]

Tis worth noting, as you point out, that a blown diode in the alternator can do this. I had it once on our scirocco. It didn't do it all the time, it depends on where the alternator "stops" when turning the motor off.

Sent from the pub.

Just a question that could help the OP here - if it were the altenator, wouldn't the problem still be there with ignition off?
It reads as though the OP can switch off the ignition and the fault disappears.
As the starter cable is connected to the altenator and battery irrespective of whether the ignition is on or off - I think - then I assume it can't be that?

Correct me if I am wrong.
I don't want to confuse matters here or hi-jack the thread though.

[Mocki]

So taking the blue wire off the alternator would have the same effect as turning the ignition off if it were the alternator

And taking the main charge wire off while the ignition is on and the drain is showing would also prove or disprove the alternator

[ghost123uk]

a blown diode in the alternator can do this.

if it were the alternator, wouldn't the problem still be there with ignition off?

Yes, you’re right, it would. (thread 2 pages long + "sent from the pub", on a phone)