alternator and engine running relay question...

[tony811976]

hi what a great find this forum is.

im a mechanic of 20 yrs and learned everything by trial and error. im a fiat man but the wife loves pugs and i must be honest our w reg 2.0l 406 executive is a stunner.

we have had it a few days and there is a problem that came with the car.

revs were going up and down a bit.
my first thought was some sensor.
after an hour or so it turns out the alternator is turning on and off hence the revs up and down.
there was a relay clicking in tune to the revs and this turns out to be the "engine running relay"
i have worked out that the relay detects an alternator charging an knows the engines running, so allows various items to work(interior heater is one)
the alternator is brand new and charging (13.8 to 14v) but only when the little alternator spade is disconnected, but then the engine relay is off and the interior heaters dont work
on a normal relay this little wire needs to be earthed by the alternator to extinguish the charge light, but it seems on the 406 it needs power to work the engine running relay and put the light out.

ok so my question is am i right in assuming this alternators little spade connection should put out 12v to power the running relay????
the alternators brand new and i dont want to change it untill someome can confirm the above.

great site and sorry for the huge first post.
thanks
tony

[tony811976]

bump.

anyone please

[steve_earwig]

Hi there, welcome, sorry about the collective "huh?"

I thought the engine running relay was controlled by the engine ecu rather than the alternator. I presume the small terminal is the charge lamp feed, the other side of which should be the ignition switch. Or the engine running relay. Perhaps if the ecu isn't putting out 12 volts for the relay, the relay is using the 12 volts from the alternator instead, which is overloading it and this is making it turn on and off. Or something...

[tony811976]

hi the wiring diagram in auto data doesn't clear it up either. if i connect the wire to 12v the battery charge fault light goes out and the interior fan starts working as the engine running relay comes on and stays on. so it does need 12v or its a bad circuit elsewhere . ive done the earths on the engine(big black one) and the ones by the battery(yellow green)

any pug specialists near swansea that would know whether this little spade puts out 12v when it starts charging or shoud it b an earth switch like a std alternator.

every alternator seller cant help me on technical items
thanks

[tony811976]

ok. so as far as i managed to work out yesterday with the help of autodata is that the relay needs 12v from the alternator to tell the car its running charging ,it then allows all the power hungry items to work, i suppose so it doesnt flatten the battery really quick if its not running.

the relay also has + and - stamped on it and the + goes to the small terminal . i did think its may be tracking thru somewhere else instead but it works perfect with power inserted.

it may b something to remember if anyone has power issues with the a/c etc if this relay is not working/powered all sorts of systems will be not working.

the alternator is brand new but assume its faulty, it charges fine so i have made a little circuit of my own for the time being just been out and it started thismorning too. so its staying as it is for now.

cheers guys

[poddack]

What engine has yours got. One thing I have noticed with mine is she smokes a lot more if the accessory belt is missing, I'm guessing (because I haven't measured) that the glow plugs are off if the alternator isn't working.