Electrical help needed please

hi . can anyone help

we have a 1996 fiat ulysse

1st , the red battery light glows dim from the time u turn the key till you leave the car ( we have changed the alternator for a new one and it still does it )

2nd, while using the car a couple of times we been driving along the radio goes of and the the rev counter dies... but i can still acelorate? and then all of a suddne 30 secs after the stero comes back on and the rev clocks working. it did it to hubby and cut out and then started again?




and this is todays progress

"ok chaps i've been freezing my fingers off with the car.
used my new mutimeter to check a few voltages and i'm just a tad confused. even though i have the wiring diargams.

i think the ingnition light glowing is down to the charging cuircit with seems to have a problem when you first start the car.

right heres a few questions.
1. on the alternator, what does the smaller of the two wires do? the big one i know goes to the battery and the small goes indirectly to the battery light on the dash.
reason:- when you first start the car the voltage across the battery is 12.18v thats lower than the 12.40 it is before starting, and there is no voltage on the little wire. if you rev to 4000rpm the voltage across the battery is 14.45v and you get the same voltage on the little wire.

i've checked the ignition relay and its fine.
i've checked the ignition barrel and its fine ( lots of litte bits)
weve had the battery checked and its fine

just can't understand why the poxy little light is just about glowing.
i think that what ever this fault is, its causing most or all of the probs with the car.

your all going to say its the alternator but thats new *brand new*

Help me

thanks in advance