Can anyone help diagnose my MOST stereo problem?

[Duncan Frazer]

Hi everyone - I've got an intermittent problem with my PCM2 Bose system in my C4S. Sometimes the system will work fine (like when I bought the car and ran it for 2 weeks!) and then other times I'll get no audio when switching on and an error on the screen that there is a problem with the changer, amplifer, and telephone module. When in the fault condition the radio visually is fine (station name, volume control) but pressing the tel button returns a "no telephone module" error. I've tried a few bits:

* drivers's seat out (UK car) and checked the telephone module MOST connection.

* head unit out and checked connection

* amp out and checked connection

No real improvement from that lot (although 30 minutes later the radio was working ... and then died again :(). I'm hoping that someone can hand out some basics for how MOST works so that I can diagnose the fault. I don't have PIWIS but if there's a genuine way of furthering the debug I'll pick a cable up.

* Red light - when should it be in the cable? When I checked the MOST connections to the telephone module I didn't see any red light in the optical connector. When I removed the amp I did see the light. I don't recall exactly if I'd turned on the ignition before starting the telephone work (but its likely I guess), I'm pretty sure I did after the telephone and before the amp cable check. Does the red optical light come on only when the head unit is active, or is there a timeout that it stays on for after the head unit is off, or maybe its on all of the time (unlikely!).

* What can I do with the PIWIS software? Frankly I've no interest in the telephone module and I've read that its quite high up the list of MOST functions that the radio checks on power up (no way to back this up though). Is it possible to disable and enable the separate MOST bus functions to fault check which item is causing the problem?

I'd be really grateful for any advice!

[mffarrell]

Hi everyone - I've got an intermittent problem with my PCM2 Bose system in my C4S. Sometimes the system will work fine (like when I bought the car and ran it for 2 weeks!) and then other times I'll get no audio when switching on and an error on the screen that there is a problem with the changer, amplifer, and telephone module. When in the fault condition the radio visually is fine (station name, volume control) but pressing the tel button returns a "no telephone module" error. I've tried a few bits:

* drivers's seat out (UK car) and checked the telephone module MOST connection.

* head unit out and checked connection

* amp out and checked connection

No real improvement from that lot (although 30 minutes later the radio was working ... and then died again :(). I'm hoping that someone can hand out some basics for how MOST works so that I can diagnose the fault. I don't have PIWIS but if there's a genuine way of furthering the debug I'll pick a cable up.

* Red light - when should it be in the cable? When I checked the MOST connections to the telephone module I didn't see any red light in the optical connector. When I removed the amp I did see the light. I don't recall exactly if I'd turned on the ignition before starting the telephone work (but its likely I guess), I'm pretty sure I did after the telephone and before the amp cable check. Does the red optical light come on only when the head unit is active, or is there a timeout that it stays on for after the head unit is off, or maybe its on all of the time (unlikely!).

* What can I do with the PIWIS software? Frankly I've no interest in the telephone module and I've read that its quite high up the list of MOST functions that the radio checks on power up (no way to back this up though). Is it possible to disable and enable the separate MOST bus functions to fault check which item is causing the problem?

I'd be really grateful for any advice!

Does the red optical light come on only when the head unit is active, or is there a timeout that it stays on for after the head unit is off, or maybe its on all of the time (unlikely!).

I noticed on my car the FO is lit all the time. Looks like you may need to take a look with a PST2 or PIWIS.