I have an '04 MCS equipped with the capricious HK system as well as factory Nav. On a recent trip using the Nav and listening to the radio, the radio got a little louder and went fuzzy and static-y, as if I were out of range of a radio signal (those of you who regularly travel central PA know what I mean). I figured that the amp had finally given up the ghost, but my next audio direction from the Nav lady was also fuzzy and static-y.

I have searched through the posts here and have not found a similar problem. Almost everybody who has complained about the HK amp indicates that there are pops and crackles on one side or the other, and then no sound at all. More than two weeks later I still have the fuzzy radio and Nav (and I still get infrequent pops and crackles on the left channels)

I still have all functions and can hear the radio as if the antenna were disconnected, but the Nav audio suffers the same distortion. If the Nav audio signal is routed through the amp, then I will assume the amp is bad and decide what to do next. But my researches here lead me to believe that the Nav audio goes direct to the HU. If that is the case, then my HU is bad (a much happier problem).

Can anyone help? Does the Nav audio route through the amp or is it wired directly to the HU?

 

According to wiring diagrams, with an HK system, audio is routed from the Nav computer directly to the HK amp. This pretty much narrows the issue to the HK amp.

But in any case, your analysis wasn't correct. Even if the signal went to the HU first, the path would have been Nav==>HU==>amp==>speaker, and the fault would have been either HU or amp.

 

That makes sense. And it is still either the HU or the amp. Has anyone had an amp go bad like this?

 

LOTS of people have had the HK amp go bad. The HU, not so much.

 

No, as I said, the Nav is wired directly to the HK amp (bypasses the HU). All the evidence points to a malfunctioning amp.