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Discussion Starter #1
I have a 2002 ML500 with an Alpine MCS head unit with CD drive and NAV. The vehicle is also equipped with TeleAid and a CD changer.

When I purchased the car the head unit would power up but there was no output/sound and it was displaying the error message about TeleAid not working/see workshop. I sent it to an Alpine repair shop in NJ for rebuilding, after which it worked - intermittently. Here's what happens:

Power up the head unit and no sound. It also does not recognize the CD changer, as the icon for the internal drive shows up on the screen but the icon for the changer does not. If I remove power and the fiber connection from the head unit, reconnect the power harness, then the fiber, it will recognize the CD changer and I'll get sound. It might take 2-3 tries to get this to happen, but it will eventually. Everything will work fine for a day or two, then the issue returns - no sound, no recognition of the CD changer.

I have an SDS system, so I can "see" the fiber loop and run diagnostics. Because the TeleAid is no longer functional, I had reprogrammed the system to take it out and bypassed the fiber with the proper fiber splice connector. However, the issue was the same prior to making this change, so I don't see it being the culprit.

Interestingly, when I run the diagnostics in DAS, it "sees" the head unit but not the amplifier or CD changer. This despite everything working properly. I can add them in through reprogramming, but when I scan after doing so they're not there.

In a nutshell, it appears that the system is randomly not recognizing the sound system or CD changer upon power up. Connections, both hardwired and fiber, have been checked and tested OK. I'm not quite sure where to go to at this point.
 

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This reads as if the problem is a disruption of the fiber optic loop, either by a bad connection or a malfunction in one of the components on the loop. Since you have checked connections, I would suspect that one of the components is not passing the signals on. You can check this by using the same type of splice connector you did for tele-aid, at eacg successive component prior to the HU.
 

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Discussion Starter #3
Thanks, Skylaw, I knew you would weigh in...

That was my next step, that is, going through and bypassing each component and just using it that way for a bit. The only issue I see with this is if I attempt to bypass the amplifier, as doing so would eliminate any sound. However, I could do it just from a testing standpoint to see if it acts up.

If I change adaptations to eliminate the TeleAid, I found that I can bypass the fiber but I can't disconnect the harness to the TeleAid device under the passenger seat, as this creates issues with the ABS system as it's wanting to "talk" to the TeleAid in the event of an accident. I went in and changed adaptations to eliminate the TeleAid, but then I get an SRS light as the ABS still wants to see a signal from it, even though I've eliminated it in the adaptations for both systems.

I'm wondering if there is a damaged fiber somewhere in the vehicle that's causing the problem?

Dan
 

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The order in which the D2B ring is coded can affect the performance of the components on some models. For example, when adding a CD Changer and CTEL to a W210, you must code the fiber ring order a static way - not the way your vehicle is physically connected.

Make sure that your D2B ring is configured as in this diagram.

2002_W163_D2B_Configuration.pdf
 
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