Hi guys,

Currently working on my dads focus due to the battery light being on.

Put it down to a duff alternator due to the lack of voltage coming from it. Changed the alternator with a brand new genuine unit and im now getting voltage...13.5v with 3 pin connector on and 14 with it disconnected!

So far all fuses see fine, earth measuring ok with meter.

Wondering now if it's a smart charge error. stumped

Cheers

Stef

sounds like the old smart charge harness issue where a broken wire causes it to switch to normal mode,in these cases mate ford do know there stuff the wires could be duff anywhere from behind the arch all the way up to the alternator it may be easier to have them test it

Reluctant to let them look at it just now, if it is a wire problem somewhere as you and John have suggested then I will try and locate it myself.

I'm a marine electrical fitter to trade so i should be able to find and repair it - in theory haha

Cheers mate

from what i remember the main smart charge plug about 2 inches down was where it was common to break and behind the drivers front wheel arch good luck

from what i remember the main smart charge plug about 2 inches down was where it was common to break and behind the drivers front wheel arch good luck

the wiring at the alternator looks to be ok but i cant remove the wiring from the ecu to test it so its gonna need to go to ford i think..damn

what a silly place to put the ecu..inside the wheelarch! i noticed the wiring inside the plastic box is wet and covered in crap so thats probably not helping.

well the car has been at ford for 10 days and they have admitted defeat. they have went from one story to another, basically they dont have a clue what the fault is, the have blamed everything they possibly can!

they have advised to just drive the car as the battery is still charging, but my concern is what happens if a fault does develop, theres going to be no warning - hardly great if you are on the outside lane of a motorway...

so im now back to square one.

thats hardly an answer is it? as a last resort perhaps an auto electrician is the next step though remember the smart charge will put less voltage to the battery if the electrolyte is hot the battery is fully charged or the outside air temp dictates have you had the battery checkd for a faulty cell this can cause those issues

thats hardly an answer is it? as a last resort perhaps an auto electrician is the next step though remember the smart charge will put less voltage to the battery if the electrolyte is hot the battery is fully charged or the outside air temp dictates have you had the battery checkd for a faulty cell this can cause those issues

fords finest..

they have had an auto electrician look at it, who pointed at the alternator - so they tried a third one from a different batch.

The battery is fine, responding as it should to load etc.

they have reduced the bill to 1hrs labour, so thats £80 plus vat.

I know an auto spark so i might get in touch with him.

once i get the car back in the morning i can maybe getting on with fitting the new exhaust that i should have done 10 days ago...

well lets look at it from a sherlock holmes way the batteries fine the alternator has been checked and a second one fitted with the same result so it has to be either the wiring the ecu or a sensor linked to the smart charge my dear watson as the alternators all act the same i would suspect its the wires there arent that many things it could be

well lets look at it from a sherlock holmes way the batteries fine the alternator has been checked and a second one fitted with the same result so it has to be either the wiring the ecu or a sensor linked to the smart charge my dear watson as the alternators all act the same i would suspect its the wires there arent that many things it could be

very true, its had 3 alternators - all the same and one of which was from a different batch

battery appears fine.

ECU is fine im told, they cant find anything wrong with this.

The red wire supplying battery voltage to the alternator is fine.

the only thing i cant test is the 2 wires to the ecu from the alternator.

Maybe need to connect up an oscilloscope to these and see if there is a signal and what it looks like

if it was a sensor related to smart charge, a temp sensor for example. i would imagine it would use reading from the engines sensors for air temp etc? there is no running problems of any sort so im thinking this is not the issue.

have to agree doesnt sound like a sensor issue dug this out but you need a scope.

if 13.8 v is measured across the battery with 3pin removed its not a smart charge fault.

the 3pins are

pin1 alternator feedback

pin2 alternator load request

pin3 reference voltage

pin3 should match battery voltage and is fed from a fuse in the engine fuse box a high resistance on the fuse causes a voltage drop and smart charge drops out.

to test pin 1 the waveform should remain constant if it mirrors pin 2 then the alt or smart charge is faulty

pin2 is the request from pcm to alt and it should be a square wave pattern that changes with load if theres no change pcm at fault

well i know we have about 13.8v -14v with the 3 pin connector unplugged.

reference voltage is fine

its back to these 2 wires to the ecu causing grief again. as i cant check the resistance of them, i can only check for a short to earth or between each other im going to assume they are fine and check the signals im getting with the scope.