04 Zafira MW radio band interference

[smcf]

We had our CD stereo unit replaced in our Zafira under warranty as it would switch itself on at will, mostly during the night!!!!

New unit is an updated model, but essentially the same. Works OK, except when we tune to anything on MW band on the M40 between London and the Midlands. On an evening run, we tend to tune to TalkSport or 5Live. Trouble is, reception is fine within the M25. Once you get out of that area, the signal deteriorates, and there is electrical interference that peaks when we drive under motorway bridges. this persists almost the entire way up the M40.

At first I thought it was a problem with the Talksport signal, but when I tuned to Virgin and 5Live, it was a similar story.

This electrical interference is proportional to engine rpm, as when I lift off the accelerator pedal, the pitch gets lower until I put my foot down, when it gets higher once again.

this leads me to think that there is some sort of earthing problem, and we are picking up electrical signals off the alternator.

FM is fine, and before anyone asks, yes the aerial is still fitted!!!!!!

Anyone else experienced this type of thing, or got any ideas as to what it might be??

[glendle]

Having had the joy of running 6 astras, 2 zafiras and 2 vectras i can safely say that it is a common problem ofen caused by the aerial on the rear of the roof. there is some circuitry in there and seems not to weather very well, also the whip aerials aren't too good - so much so on my van that i run for work, i got one of those bee-sting cheapo screw in replacements and all is now well and i pick more fm up as well. I also have ripped out the sometimes appauling VDO unit and replaced with a sony. The wiring harness needs the yellow and red wires swapping (ignition / permanent live feed) and the connector for the remote steering wheel buttons is £30 from halfords. I seemed to get a lot of interference on fm from the stock VDO CDR500 CD model and CAR400 Cassette model.

[welshwizard]

I never had problems with the CDR500 on Vicky or the CAR400 on Peggy

Have you tried both 5live frequencies - 693 and 909?

I get 5live here in the Netherlands in my 9-3...good for saturday afternoons and sports report...

Mind you I have not tried 657 for BBC Radio Wales though..

[smcf]

Tried both 5 Live frequencies, both Talksport frequencies, Virgin etc. The noise is there to different degrees, but definitelt related to engine speed.

[Tony Ennis]

Usual culprit would be the alternator in which case an aftermarket condenser (suppressor) might do the trick for a couple of quid. Could also be a poor earth to the bonnet.

[Richard_C]

First thing to check is earthing problems somewhere (if the unit was swapped and that is the only change, maybe even the earth to the unit itself or the aerial is not plugged in as well as it might be.) It has advantage of being free (except for your time).

Weather and time of day are also influences - dusk often seems a bad time for any amplitude modulated reception.

If you go the suppressor route I think Maplins do a fair selection.

MW reception seems particularly grim in most of the UK whichever car I drive: its only a real problem if I want to listen to a football match on 5 - why the BBC combine the least clear channel with an unintelligible commentator is beyond me.

[smcf]

It's strange because this problem has only arisen since the new radio has been fitted.

I never experienced this with:
my H reg Fiesta,
the wife's F reg Escort,
the wife's 02 reg Rover 25,
my V reg 9-5,
my S reg Escort,
our 04 reg Zafira (pre-radio swap)


Er, so there you have it!! Hopefully, drive Vauxhall in Leamington will sort it on Monday!!