I am experiencing an intermittent audio issue with my PCM. It's a Bose system on my 06 CS. No audio whatsoever from the speakers - no sound from radio, CD, or LA Bluetooth adapter. It happens mainly in the AM when I leave the house for work, and then sometimes it fixes itself by the time I start it in the afternoon. I have reset the system several times by pulling the fuses and it comes back for a few days, only to go bad again. First I thought the LA Bluetooth adapter was failing but after some searching here I see that it may be a known issue with the Bose amp. And it may require a new/repaired amp.

So can ask for recommendations here? I am thinking maybe it is time to upgrade to an aftermarket system, but not sure if that will anyways require a new/repaired Bose amp. If it does then it makes sense to just get a working used amp. I see several for sale on Ebay are for sale but cautious that maybe they are for sale because they started to fail and were replaced with aftermarket units.

If anyone here has a Bose amp in good working order I would be glad to purchase it.

Thanks in advance for any help solving this issue. Its my daily driver and I do need the music to get me to work everyday.

 

Mine does the same thing. Related to colder temps in the morning. Has gotten worse. Used to only go out when very cold, now maybe 60 degrees. Intermittent. Also has made loud screechy poltergeist sounds.
Its unusual to lots of common problems here. Their audio goes out with heat, not comes back on with heat. I live in AL and it may be related to elevated interior temps in the summer deterioration the components.
If I remember, if you have no sound at all, its prolly the head unit.. Else, its the amp.
Would love to know how to fix it. Hate to replace the head unit and thats not it. On my list.
A few good threads on the issues.

 

I had this problem as well. Generally the subwoofer would put out muddy sounds if the volume was turned high. Sometimes nothing. Generally the failure would occur upon a restart after a 30 plus minute drive. But it did happen once at first start in a cool garage. The problem was very intermittent, gradually becoming more frequent. Sometimes cycling on and off fixed things. Sometimes I just had to wait for it to self heal over time.

Nothing is worse to fix than an intermittent problem. You can make changes but there is always a nagging concern that the problem remains under the surface. So everything that follows is provisional.

There was one report on this Forum that replacing the PCM with a different system fixed it, but there was no long term confirmation (that I saw). Another member here reported putting a different amp in to fix this. Again, no long term confirmation.

I installed an add on board (to extend cables out of the PCM) that attached to another box for Carplay / AA. This bypassed the bottom two thirds of the PCM but not the top third.

The problem persisted. So the PCM was not isolated as the problem, but also not eliminated.

I then decided to dig deeper based upon the reports of others, but focus on the amp only. The PCM is different between .1 and .2 cars while the amp is the same. So attack the common component. Possible problems ...

1. Connections. The connections at the PCM were cleaned when the PCM was updated. All plugs were cycled multiple times to clean the pins. So I was only concerned with connections at the amp.

2. Cold solder joints.

3. Compromised power caps.

4. Heat sink thermal compound that might be dried out and inadequately conducting.

So I pulled the amp, replaced the caps, resoldered components, and renewed the thermal paste. Then I cycled the plugs as I reinstalled the amp.

The result? So far so good.

The conclusion? I threw away the one fix at a time process so I can't say what the actual fix is. But it looks good (so far). So one of the above appears to be the culprit.

Note: The amp is a multi layer board. Things don't desolder well on these boards. You will need to heat the cap legs and gradually rock each cap until it is released. Then add solder to suck the remaining solder from each hole. If you are not experienced with PCB repair I would advise you to not replace the caps.

So I believe the problem is in the amp, at least in my case. And it appears this is an easy fix, although getting the amp out was a bit difficult ... I hate pulling on connectors. There is a latch on one connector that needs to be levered to the side to release the plug.

Anyway, if you opt to do the above it isn't too difficult to figure the details on the fly.

Good luck and please keep everyone updated on your findings.

 

Thanks for the detailed post. You really DIY'd this. I am not good with electronic repairs like soldering etc so probably will not go as deep as you did. I have a couple of weeks off coming during the holidays and will look into the amp connections etc. Its been working fine the last two days on its own.

 

There's a real frustration in intermittent failures.

Jameco is a good source for hobbyists to pick up things like transistor paste (also known as thermal compound or grease) as well as caps and soldering supplies

 

Update on PCM issue FYI ....

All is good and back to normal 1 week after replacing the Bose amp. No more weird screechy sounds from the speakers when entering the car, and no more intermittent audio cut-offs.

Question if and when the replacement amp will have similar issues since it came for same year car. I picked it up from a dismantler on Ebay for a very reasonable price. It took some searching to find one with a matching part number but after a couple of weeks this one popped up.

Hope this helps others with this problem. Cheers.

 

Thanks for the update. Might try this. Sounds like not very expensive and easy to swap out.