MK1 Charging Circuit Fault

[toolapcblack]

I have a 04 Focus with a battery that isnt charging when the car is running, the multi-meter only reads 12.6v with engine running!

could someone please point me in the right direction as to what tests i can run to determine if its the alternator or something else in the circuit that is blown 

Cheers

J

[Luke4efc]

If the alternator has never been replaced I'd say it's certainly due at 16 years.

[toolapcblack]

Thanks 

ok but In the Haynes manual it says the following quote:

"The dashboard warming light should come on when key is turned to pos 2 and 3 & go off immediately when engine starts. If it remains on fault is with the charging system, if the light does not come on when key is turned fault is with the alternator"

light comes on in pos 2 and 3 but stays on when engine does this imply the circuit is faulty not the alternator? any simple checks one can do

thanks

j

[toolapcblack]

so i managed to get a reading off the alternator 13.84v coming out where to look next?

[Carl123]

How come its 12.6v one minute then 13.84v the next?

Are you saying the Alternator is giving up and down readings, whenever you test it?

Also, how old is the battery?

[toolapcblack]

no sorry i get 12.6 at the battery when engine is running(so not charging), i get 13.84v measured at the alternator when car is running(obviously not getting through to battery when idling).

 

car off i also measured earth at alternator is ok and there is continuity from red on alternator to red on battery + all fuses ok

[toolapcblack]

made a schoolboy error doh when measuring voltage at alternator earlier still had jump leads on from other vehicle so was reading 13.84 actually is 12.16 coming out of alt

[TomsFocus]

Continuity is only half the story, all it shows is that one strand out of hundreds is touching the terminal at each end.  You can have a corridor 10 people wide but if the door is only one person wide it's going to hugely restrict the potential flow though it.

[TomsFocus]

10 minutes ago, toolapcblack said:

made a schoolboy error doh when measuring voltage at alternator earlier still had jump leads on from other vehicle so was reading 13.84 actually is 12.16 coming out of alt

Whoops.   Looks like it is the alternator then.  You can have them refurbished if you can't stretch to a brand new one.

[williamweb]

1 hour ago, toolapcblack said:

made a schoolboy error doh when measuring voltage at alternator earlier still had jump leads on from other vehicle so was reading 13.84 actually is 12.16 coming out of alt

You probably know a healthy alternator should be generating about 14.6 volts on the MK1👍