hi guys

i've just picked my fiesta turbo up from the bodyshop and i've got a strange problem with it when the ignition is turned off the battery light on the dash is staying lit and draining the battery when the car is running it seems fine.

i've checked the battery voltage, and checked the voltage at the starter motor and the alternator and the alternator seems to be charging ok

i'm sure it's something really simple but i've checked everything i can think of

SOMEONE PLEASE HELP!!!!!!!!!

PAUL

 

I'd say the alternator's knackered m8!

disconnect the thin wire that goes into the back of the unit and see if the light goes out.

 

even if alternator is charging when it's running

 

yes

 

what's the wire at the back of the alternator your talking about

you have the thick red wire which is the main live and a thin blue wire and a black wire. which one do you mean

 

is the light trigger wire IIRC

 

what colour is that one then

what does IIRC stand for

 

IIRC=If I Remember Correctly

Blue wire to light

As above alt could still be dodgy even if charging
Did you have welding done at bodyshop???????

 

yes

new rear pannel

 

Could be that if they didn't disconnect your battery they have fried your alternator m8

 

is there any way i can tell one way or another if it's had it or if it's just a bad connection

 

The best way is to take it off and have a look at the connections,then if they look ok take the alt to a local auto-electrics place and get it tested on the bench

Before you take it off though just disconnect both the small wires off the back and see if the light goes out,the battery light should have an ignition live feed going to it,then before the engine/alternator are turning the alternator earths the light which is how it lights up when you switch ignition on
Then when alternator starts to turn as engine turns the wire from the back of the alternator becomes live,so you then have two lives going to the light,so the light goes off then

Can't really see why your light stays on with no ignition though

Could be a problem with ignition switch on the barrel

 

I'd disagree there, all the bulb does is connect to the alternator to derive either earth or 12v. For the bulb to be on with the car switched off, there has to be a 12v supply to the ignition circuit.......the alternator is simply resting at ground.

Have you had the dash put or anything wiring related while its been in the bodyshop?

 

Looks like i wasted my breath ive just repeated what you said

This is right though

 

Wasted your breath?????You've got a clever keyboard if it works off your breath!

Just wondering if this prob could be the alt,if the alternator is supplying a permanent live(because of a fault inside alt etc),and the ign live is then the earth when the ign is switched off

Confused myself

 

Well you know, chavs steal all sorts of interesting electrical equipment

Funny you should say that...............that was the exact thought i had, thats one hell of a fault though. I suppose the diode pack could have a short and be back-feeding 12v from the battery and using the dead ignition circuits as a earth as you say.

Easy way to tell would be for him to unplug the blue and touch to earth with the ignition off, if the bulbs lights then its ignition circuits staying live, if not the its gota be the diode pack shorted

 

as my 1st post I'D say the alternator's knackered

ps I've even seen them correct themselves after a while also

 

I'm sorry

 

thanks guys for all your suggestions, thoughts and ideas

hopfully it's sorted, i've gone out and bought a new alternator and fitted in this evening

i'll have to wait untill morning to see if it's drained the battery but the light on the dash has gone out and all is looking good

thanks again

PAUL

 

Nice one

A tip for next time though, 99% of the time you dont need to buy a new alternator, can fix them for about £20