Fiesta alternator wiring help

peter212693 · 4 Feb 2010 at 23:25

Hi all,

My mums car seems to be having chargin problems still as you of you may know. Now after a couple of alternators it will wouldnt get above 12.2v when the car was running.

Now poking around tonight checking the earth points I found a plug that wasnt plugged in. It seemed to have the blue/black and blue/white wires that come from the alternator along with the main red cable in this plug. I take it this need to be plugged in lol

What do these other wires do? I know one is for the battery light on the dash as without it plugged in we get no battery dash light and we do when its plugged in, what about the other wire? Have I finaly got to the bottom of this problem?

Thanks
pete

Dandle · 4 Feb 2010 at 23:37

They are there to excite the alternator. Without the coil being excited the alternator won't produce any power.

peter212693 · 4 Feb 2010 at 23:40

Dandle said:
They are there to excite the alternator. Without the coil being excited the alternator won't produce any power.

Thus not giving enough volts to charge the battery properly? ie 12v ish rather and 14v?

Dandle · 5 Feb 2010 at 00:57

Yes you wouldnt see any charge as the alternator isnt supplying any power. So you would just be reading the battery voltage of 12v rather than 13.8v the alternator should be putting out.

peter212693 · 5 Feb 2010 at 08:14

Im bringing the multimeter home from work tonight to test it. I feel like such a **** if this works and i never noticed this being unplugged before after all the trouble we have had with it

Thanks for your help mate