wcytarga

You are right! I have a 911 996.2 Targa from 2002 (MY2002). From factory it has the following options:
- M662 (PCM 1 Porsche Communication Management screen with navigation, telephone module, radio, cassette player)
- M663 (Telephone handset for PCM 1)
- M680 (Bose sound system (analog))
- M692 (6-disc CD changer Becker Porsche CDC-3)

Regarding I believe M680 includes one.

Please let me know if I can provide more information.

Thanks @ZuffenZeus!

ZuffenZeus

You have one the most complicated of all analog (i.e. pre-MOST) systems - that is, PCM1 and BOSE with CD changer and phone. I'll have to review the schematic in the shop manual to better assist you and this system. The fact that it's blowing fuses is more reason to study the connections more closely. I've very bust at the moment and so if someone else can chime in on this that would be helpful. I'll try to look into this system on Monday.

Question - have you grounded the M680 amplifier pin as noted on page 8-9 in the attached TSB?

ZuffenZeus

wcytarga

Thank you for getting back to me @ZuffenZeus .

I did the installation a while ago but I do remember having issues at that step, i.e. not finding the black 18-pin connector cable in the picture. Could this be the reason the fuse is blowing?

I will look again and see if I can find the cable (by the end of the next week I should have feedback).

ZuffenZeus

At this point in the installation, replace the blown fuses and disconnect the special ISO adapter cable for now.

First things first... you need to follow the steps that Porsche has described or you won't get any sound out of the system. The 18 pin connector supplies power and line level audio to the M680 amplifier. The M680 amp should be located on the passenger side of the car in the frunk. You MUST remove the DSP data line #17 (black/red/yellow) on the connector and then replace with a grounded cable (996.642.587.00) on line#17 on the connector.

wcytarga

Thanks once again for the information. I replaced the fuses, removed the adapter and everything is back to normal.

I do have sound and everything works as expected, other than the sound being too loud at level 5 and some crackling noise.

As soon as I have more information I will let you know.

Thanks!

ZuffenZeus

Yea, that's because you're overdriving the amplifier.

Moehre

Hi, with help of this thread I got aware of the Porsche ISO adapter for the MY2002 Bose PCM1 CD-Changer configuration.

With the adapter in place, the sound works okayish. Low frequencies are way too loud, eben at low EQ settings and also overall volume bandwidth seems reduced. I think that is because the Bose amp was fed a slightly amplified signal from PCM but the pccm+ speaker oit level is too high. So the amp out is used and fed to the normally speaker level plug.

What surprises me in your answer is, that you recommend to ground the amp. I did not do that, since I always thought it only is possible and necessary with the m680 my 98-01 sound package. In my02 M680 was used for Bose analoge and starring with my03 for bose via most.

So my question is: do you have positive results with grounding the Bose analoge amp? I would assume that the adapter then is superficial because the speakers would require amped volume and not line level.

Also I thought the pin 18 action was to override the EQ button for the DSP of the m680, since you remove the control panel.

ZuffenZeus

That is correct. The signal level was not correct for systems with a frunk amplifier. Porsche is all it's marketing wizardry was able to sell lots of different configurations. That makes it's a big challenge to develop new technology with modern features that integrates with older systems and ISO connections. The core problem was the PCCM+ was NOT sending SPEAKER LEVEL audio to the amp when it needed "pre-amp" LINE LEVEL from the YELLOW ISO PLUG. Some configurations worked with overdriven audio, some didn't work at all. The intension of the Porsche adapter cable is not to attenuate the SPEAKER LEVEL output; but instead, route the correct LINE LEVEL audio to the amp.


The TSB was officially released by Porsche after they investigated the problem with the PCCM+ not producing sound on DSP (M680) systems. This TSB came BEFORE the release of the official Porsche ISO adapter cable. Based on reports here on Rennlist, the people affected were the systems with M680 amps. You have PCM1, (DSP)M680, and BOSE, but based on their information, pin17 needs to be grounded.

Again, every person I've helped with the M680 no-sound issue, grounded the cable per Porsche instructions and the PCCM+ worked abet the sound still being overdriven to the amplifier. That was corrected with the new ISO adapter cable. YOU, have a very unique system. Therefore, if you can't get it to your pleasure, then the best course of action would be to contact your nearest dealership and arrange a meeting to discuss resolution of the problem.

ZuffenZeus

Not following you. Are you talking about the 18-pin connector in the TSP?

iso

@wcytarga, the Porsche Loudspeaker ISO Harness 996-642-341-00 is suppose be like this. Plug A (Black / Chassis Side) directly into PCCM A. Plug B (Brown / Chassis Side) into Black Connector (Harness). PLUG C1 (Yellow / Chassis Side) into Red Connector (Harness). PLUG C1 (Yellow / Harness) into PCCM C1. I plugged C2 (Green) and C3 (Blue) into Red Connector (Harness) since I am not planning on using the CD changer.

@Moehre we have figure this out.

I have a MY2002 CR-220 with BOSE ANALOG M680, non-DSP, non-MOST. I have PLUG A (Black), PLUG B (Brown), PLUG C1 (Yellow, only 1 wire connected, BK/RED for amplifier switch On/Off), PLUG C2 (GREEN), PLUG C3 (BLUE). wiring should be similar to yours since we share the BOSE ANALOG M680 regardless of stock headunit.

PCCM+ Version: AP: 20210922 15:21 / OS: 25.0.0.6.1.0.1.1 / Purchased 05/2024

Just received the Porsche Loudspeaker ISO Harness 996-642-341-00, it did lower the gains and reduced the white-noise but it is still there even on mute and PCCM+ EQ had no effect on the subwoofer.

Without the Porsche Loudspeaker ISO Harness, very high gains, high white noise but the bass was manageable with the PCCM+ EQ. I honestly prefer the audio quality without the Porsche Loudspeaker ISO Harness but only if I can get rid of the white noise.

I gained a lot of information from these 996 PCCM+ threads. MY2002 is unique, a transition year. We don't have a DSP so there isn't a PIN 17 (DSP data line) to ground. We do have 2 amplifiers, main one which powers front and rear stage, "additional" amplifier which powers the subwoofer.

I am also wondering if we need to create a more substantial / direct ground for Plug Socket P1 (main amp) - PIN A (BRN) and Plug Socket K12A81 ("additional" amp) PIN A1 (BRN) to eliminate the white noise. This might not do anything for the subwoofer.

I went though all the secret menu settings and there isn't anything related to Subwoofer / Gain / Speaker-level / Line-level. I feel like this issue could be easily solved with software -- like a tune.

I am not sure on what to do next.

A. Direct Ground for both amplifiers -- this might solve the white noise but not the subwoofer issue.
B. Remove the Porsche Loudspeaker ISO Harness, buy 2x SPEAKER-LEVEL to IN-LEVEL ISO Adaptor and run them tandem (I couldn't find the post but this sounds promising)
C. Bypass Bose Amplifiers and run speaker output directly from PCCM+ to speaker by jumping Plug Socket P2 and delete subwoofer. @Body In White since you don't have an amp, have you found a resolution for the white noise?
D. Noise filters?

Body In White

In the time since I installed the PCCM+ in my GT3, I’ve seen a few other 996 GT3s with PCCM+ units and all of them have the white noise problem. For anyone reading this in the future with a GT3… I’m fairly convinced that this unit wasn’t designed with our cars in mind, it works, but… I suspect the PCCM Classic for the air cooled car would likely be a better choice for the 996s without factory amps.

Back to your question, I was going to try and build an appropriate noise filter, but honestly, the white noise is so faint that you can’t hear it once the car is on.

ZuffenZeus

IMHO, the white noise is audible because the signal from the PCCM+ is not being attenuated properly feeding the amplifier. Even the best of electronic sound equipment will have a noise floor (look for signal-to-noise ratio figures when comparing head units) and if the pure signal is not handled correctly, noise could be amplified to the point where you can hear it under super quiet conditions. When I was young, I got involved with installing and running big sound reinforcement systems. We would purchase brand new amps and speakers from all the best brands, connect them together and turn the volumes up all the way up (without an audio signal) just to see how good the amplification was handling noise reduction and filtering. You'd be surprised how much noise you could hear.

I agree with you. Porsche didn't really put a lot of effort in supporting the older analog cars with frunk amplifiers. Seems the MOST - PCM2 folks have the smoothest transition to these units.

philPompili

I also have this issue. That little hiss when the car is quiet. I thought it was a faulty fan somewhere, but when I realized that it was coming out of he speakers. My car is a 996.2, non-Bose, that came with a single DIN radio. The previous owner had a single DIN Alpine deck (I didn't notice any hiss, but I only had it for a week or two before "upgrading")

wcytarga

@ZuffenZeus apologies for the radio silence, life got in the way and couldn't get back to this topic.

Once again I opened the frunk and started looking for the DSP data line (black/red/yellow) and I wasn't able to find it. I took the following pictures to show what I found while taking things apart.




On #1 I stripped it all apart and couldn't find any cable that matched the DSP data line.

On #2 I stripped it all apart and found the following cables, which once again didn't match the DSP data line.








Please let me know your thoughts, and hope the following pictures help provide extra context.

Thanks!