(T) Power Steering & Sound System Electrical Fault

My wife and I own a 2000 (x-reg) Seicento. It has been a great car but over the last few months it has developed this electrical fault and I would like some expect advice if anyone visiting here can offer any help. My wife worries that it might be dangerous and we wondered if anyone else who knows this car well had ever come accross this:
When driving the car, the power-steering light sporadically comes on and the power steering fails. This only lasts a few seconds at most but may occur 5 - 10 times in a twenty minute drive. When this occurs, if we have the music system switched on, there is a loud buzz/crackle from the speakers. This lasts as long as the power steering is out and when the power steering comes back on the radio returns to normal.
We bought the car from a local garage and we always take it back there for repairs and service. They are good mechanics but not auto-electricians, and this problem is beyond them. They replaced the power steering unit for us but the problem did not go away. We have now started running the car with the fuse for the power steering out and this circuit isolated, but (although we are unable to notice anything from the steering which is now constantly un-aided) the radio still sounds out its buzz/crackle, so the fault is still there.
To isolate the radio circuit, this same fault still appeared with the radio off but the power steering fuse in. Therefore it seems to be something unconnected with these two circuits that is interfereing with them.
A friend of our has suggested that it might be a short-circuit somewhere but the job of finding it is one of checking every wire, connection, and earth. This friend has advised us to get a manual and look at the wiring diagrams to see if the radio and power steering circuits meet anywhere, or if another system runs off them. The problem with this is that I have been told that Haynes do not produce a manual for this car.
Can anyone out there offer any suggestions or help for us please? Thank you so much for any advice given.

It probably is an electrical issue of some sort. Someone here mentioned relacing/cleaning a relay in a similar context and that would explain the crackle on the radio.

There is a seicento manual -- the factory one -- available, but not through dealers. It's on a CD and can be found pretty regularly on eBay. One of the guys on the clubcento forum knocks them out very cheaply if you ask him nicely.

But this is a safety related issue of a high order. I'd be inclined to take the car in to a FIAT dealer, explain the issue, point out that the speedo works (I take it it does), the rack has been replaced, and the crackle from the radio. Shouldn't cost you much at all.

Get the car checked by an auto electrician. It sounds like alternator is on its way out.

Cheers

D

Take it to dealer who can monitor the steering sensors,safety above money.Could be alternator as mentioned here,again dealer can extract relevant codes.

Thanks for the advice. It's booked in to an auto-electricians for Thursday.

Fiat dealer would of been better,anyway let us know what happens.

Not neccessarily. Any autospark worthy of the title will have a full version of 'expert' on a handheld.

Will then be able to do the repair without having to wait three days for parts.

Cheers

D

VOR next day delivery on parts...anyway no offence but I agree to disagree