JTT

Ok, so here is the story. I purchased a 2003 996 C2 Cab with CDR23 BOSE system in the summer. The previous owner installed an aftermarket head unit as he said the battery died and when he replaced it the stereo stopped working, so being a long way from a dealer, he installed an aftermarket head unit. He gave me the original amp and head unit with the car in case I wanted to put it back in.

Well, I decided to do just that. So I removed the aftermarket one and the additional wiring harness that tapped into the speaker outputs from the amp. I put everything back to stock including hooking up the MOST cable to HU and amp and hooked it all up. I was thrilled when the head unit lit up, tuner worked, CD player whirred and whined! WHOO HOO! ....ah, but no sound

Fuses at panel are fine. Fuse at back of HU fine. I know the speakers are all working as they were with the other HU. There seems to be 12V getting to the amp. Obviously power to the HU as it all lights up, etc.

Is there a way to test the output from the HU or to test the amp to see if it is dead? This MOST stuff seems to really have me hamstrung. Any help appreciated.

12v Nick

Sorry I didn't see this earlier JTT.

With MOST, there is unfortunately no way to test the integrity of the signal being sent down the chain. One thing I would do is pull the fiber optic plug from the amplifier while the system is powered up and look at the ends of the cable. One side should have a red blinking light. This is indicating that some signal is being sent to the amplifier from the head unit.

Also, keep in mind that things like CD Changers and Phone kits were also on that original MOST loop. If there is a break in the chain, the system will not fire up. The two MOST wires are "send" and "receive" so both are needed to function.

Let me know if that helps.

JTT

Thanks Nick. I do get the blinking red light at the amp end of the MOST cable. To the best of my knowledge my car didn't have CD changer or phone system. I have dug around and can't find any more MOST connectors hidden away. That said, if a component, say a CD changer, was disconnected, would that break the chain? If I hooked up the amp and unplugged the MOST cable at the HU end, should I see a light at the end of the cable from the amp?

Also along that same line, how does the MOST cable run? Meaning is it from the HU to the CD changer to the amp? If I was to try to trace the MOST cable where would I except to find any additional connections? Wiring diagram really doesn't show how they connect)

12v Nick

The MOST system all starts at the head unit — everything else shoots off from there. If you have a break in the return line from the amp that could cause your issue. It's unfortunate that there is no way to test the amplifier itself, and it sounds like there's a possibility that you have a bad one.

If you wanted to test a break in the loop, you could order a MOST extension cable and connect the head unit directly to the amp. Although they are not cheap cables and it would only be used for testing.

Here's one on Amazon:

JTT

Thanks Nick. Likely not feasible to buy cables to test. Maybe I'll get lucky and find someone local and nice enough to let me plug in their amp to test :thumbs: More likely I'm going shopping for a new head unit. Fortunately HU are cheap these days (been a long time since I shopped car stereos). PIA will be finding another amp to drive the subs. Amp for subs may be a "next year" project.

Any suggestions for a decent, inexpensive bluetooth HU...that would allow future amp addition?

Thanks for your help!

Alan Szelesta

Ok so I have a 2004 Porsche Cayenne turbo. I pulled the radio out and their is a green plug labeled fbas and the wire is cut my question is does anyone know what fbas stands for and does anyone know where it run too? Any help or guide in the right area is much appreciated

Thanks
Alan

32krazy!

i have a cdr23 if you need one