Hi people my friends battery light has just come on there 2ltr diesel Ford Kuga.Ive been to have a look at it and when you start the engine the voltage is about 12.50 and rises to 13.50 volts.If the engine is reved the voltage goes to about 14v then drops off.Ive check the voltage from the back of the aternator so I know the wire to the battery is ok.

I take it its a faulty alternator.

 

Do they not have smart alternators that only charge when they need to?

 

Unplug the 3 pin plug on the alternator, it should then revert to working as a standard alternator should.

 

Yeh its a smart charge alternator.

 

Right so I take it the voltage should rise.

 

Yes if you unplug it you should have around 14.5v constant just like a normal alternator would. However if the voltage is currently rising and falling as you rev it, then I would suspect fooked alternator, as smart charge should not do this.

 

as said, pull the 3 pin plug off and it should be 14.5 to 14.9 if either side of that the alternator is fucked.

 

Right thanks for this. I was gonna pull the 3pin plug off too.

Ive changed loads of the small looms on tranny connects cause the wires snap due to them rubbing in the plastic shroud.

 

Im at work so to compare I took the 3 pin connector off a tranny connect alternator and the voltage dropped from 14.45 to 14.05 volts??

 

Shock when these threads arnt in the general car discussion they never get any interest... aaaahhhhhhh rant over lol..

 

Glenn, on the Kuga, is the battery light on all the time once you start it, or does it go off then come back on after a few seconds? If it goes off and comes on after 20-25ish secs , it points to a fault in the smart charge circuit.

On the old Kas they had a fuse for smart charge above the fusebox that was easy to miss.. Might be worth checking all the fuses at least!

Haven't seen any probs with the Kuga ones yet but first time for everything!

 

I fixed it today. I replaced the alternator and the light went out. It was still only reading 13.67 volts on the multi meter.