Aftermarket Radio in harmen Karden

Hi i have a 1998 series 2 with stock Harmen system , i want to replace the stock radio for a Pioneers single din, had a look at the old unit and connectors are standard ISO connectors but i have plugged in the pioneer and nothing, no sound, all powers up ok , finds radio channels but no output.
Guess its to do with the amp? anybody solved a similar problem??
If i get it working i will buy the steering wheel adaptor.

Thanks

I'd love to know the answer here.. I've just pought a disco td5 but the amp under the seatd been removed.. Can I bypass it ?

Connect the Pioneers head unit pre-amplified output to the amp and adjusted the output gain u and should have sound. Assuming the amp has a power supply to it.

Following on from what Discool has already said, in both the Harman Kardon and the high-line ICE systems, the amplifier under the passenger's (left hand) seat drives all of the speakers (3 in each door and two in the tailgate) so a straight bypass might require a bit of working out of the speaker wiring.

The amplifier unit has a main 12 volt supply to it, as does the CD autochanger but there is a +12 volt "enable" signal from the head unit which is used to switch on the audio amp, the CD player and the two aerial amplifiers; medium/long wave and FM. The enable voltage leaves the head unit on pin 5 of the "power" ISO plug.

In after-market equipment documentation this connection is sometimes referred to as accessory wiring and suggest that it's used for automaticlly extending telescopic aerials.
Without that voltage the amp won't switch on.

What great replies, sounds to me like this is the solution and thanks for your efforts.

David