Hi all.
You recently helped me out in a few probs and hoping that the guru's of the day will be able to save the day.


I have trawled all previous answers to other and can't seem to find what I'm looking for.

The alternator was replaced recently but due to other issues the car has done virtually no mileage at all.

The battery warning light will not go out. The batt has been fully charged overnight and starts at 12.3 volts.
On starting the engine the volts will drop to 11 and then decay slowly. The voltage at the alternator is the same .
I have tested for a good earth connection etc and all seems OK. On removing the signal wire from the alternator I am getting no volts between earth and the central pin. One of the other pins has approx 6 volts continuously and the other pin shows 5 to 6 volts but switches with the ignition. There's no change in the output from the main terminal of the alternator when the engine is running. I desperately want to sort this as I need to get it mot'd and back in the road.

The alternator is brand new.

Any help gratefully appreciated.

Well 12.3 is no good, needs to be 12.7 or above.
I would have the battery tested as it looks like is has had it's day! 2023 P440e SE Dynamic on order -cancelled

2022 HSE Dynamic P400e

2017 Discovery 3.0 HSE Silicon Silver Nimbus interior and a few extra toys SOLD

2013 HSE Black, Orkney Grey, Ebony Seats and Ivory Interior SOLD

2006 HSE

Plus a few other cars inbetween!

Have just recently changed the alternator on mine,,, battery light first showed it's face when the alternator died. When replaced on first start the battery light stayed on for a very short time then went out.
As jimbg said 12.3V is not good,,, but if I'm understanding this correctly you say after starting the voltage drops?. Even if your battery is faulty you should still see 14.7V at the battery and anything up to 60 amps current wise from the alternator,,,,,,, if not your alternator is faulty. What make of alternator did you fit?,, possibly recheck the connections are good including the earth point right next to it. As I said output from mine with a new battery was 14.75V and 60 amps initially,, after a short while the current dropped to 20amps because the battery was new and charged but voltage would always remain at 14.7. 2010 RRS, TDV8
bali Blue / colour coded
side steps / flappy paddles
black perforated leather
22" overfinch
heated everything, TV,fridge ...... now with gold calipers and mud flaps !( black mud flaps that is) !!
Many years ago,,,,, 1955 series 1 landie , sometimes wish I had kept it

Hi.

That's correct. When the engine starts the voltage drops. The engine is effectively running on the battery alone. There is no output from the alternator. I'm not sure if it is getting the signal through the smaller plug to initiate charging.

Did you fit a denso alternator,,, not a reconditioned non branded unit? 2010 RRS, TDV8
bali Blue / colour coded
side steps / flappy paddles
black perforated leather
22" overfinch
heated everything, TV,fridge ...... now with gold calipers and mud flaps !( black mud flaps that is) !!
Many years ago,,,,, 1955 series 1 landie , sometimes wish I had kept it