@Graham Butcher interesting that you’ve worked in refurbishment. In your experience would they change the diodes ? Or just refurbish the mechanical parts, bearings etc. I assume they would just spin it up and check an output voltage is present.

11 minutes ago, trickyskoda said:

@Graham Butcher interesting that you’ve worked in refurbishment. In your experience would they change the diodes ? Or just refurbish the mechanical parts, bearings etc. I assume they would just spin it up and check an output voltage is present.

Generally they would do the same as anybody involved with electronics would do, check the diodes with a test meter in forward and backwards bias and if they read OK and don't show any signs of being bashed up etc, just leave them alone. Generally it is a case of fitting new bearings, skimming the slip rings, and fitting new brushes and sometimes new stators and or rotors.

Edited 1 June, 20251 yr by Graham Butcher

The alternator is off the car again. Taking it back to be tested tomorrow so let’s see how that goes! Will update.

1 minute ago, trickyskoda said:

The alternator is off the car again. Taking it back to be tested tomorrow so let’s see how that goes! Will update.

Good luck. When you think about it logically it just has to be the alternator, there is quite literally nothing else it could be. That wire only goes to the alternator and the parasitic current disappears when you disconnect the wire.

Update: Wigan alternators tested the alternator this morning and conceded a diode must be leaking. The unit was replaced and I've just put the alternator back on the car and so far so good! the alternator is not causing any unwanted current drain. So it would appear that I was unlucky enough to have two faulty replacement units.

Out of interest, there is a 5A fuse for the "Phone" circuit in the engine bay fuse box. This now seems to be drawing 200mA when the car is asleep... it may turn off after a while but what is the actually powering ? Since there is not a phone in the car.

Thanks again,

1 hour ago, trickyskoda said:

Update: Wigan alternators tested the alternator this morning and conceded a diode must be leaking. The unit was replaced and I've just put the alternator back on the car and so far so good! the alternator is not causing any unwanted current drain. So it would appear that I was unlucky enough to have two faulty replacement units.

Out of interest, there is a 5A fuse for the "Phone" circuit in the engine bay fuse box. This now seems to be drawing 200mA when the car is asleep... it may turn off after a while but what is the actually powering ? Since there is not a phone in the car.

Thanks again,

That sounds like a great result. The "phone" might be an emergency SOS system that will alert the authorities to your location if it detects that the car has been in a strong enough crash that you may require assistance. Has your car got a dedicated SOS button?

Assuming that is what that 5A fuse is for, it will no doubt be controlled, possibly by the body control module, and the ECU's are typically still active and drawing reasonable power until about 10 minutes after the ignition was switched off, I suspect that @Breezy_Pete might be able to confirm this.

What fuse number is this 5 Amp 'phone' fuse?

Glad they sorted a fully working alt for you. 🙂

Engine bay fuse 9, I suspect.

Seems you do have the telephone preparation package, according to car data.

"Telephone/telematics 9ZG - preperation [sic] for mobile phone with hands-free system"

Not sure how you'd go about uninstalling/deleting that, but you could try simply removing that fuse and seeing if that causes anything else to stay awake.

"Whack-a-mole" springs to mind. 😆

Thanks both for your help 👍🏻👍🏻