Assuming you do have a separate power amp, the output from the OEM head unit is line level (ie very low power, not suitable to drive a speaker direct) and this feeds a big power amp elsewhere in the car. You therefore use the line level outputs from the D3 (RCA jacks) and ignore the speaker outputs. Since the original power amp is driving the original speakers, you don’t care about their impedance.

When I installed the D3 I suspected this was the case. Here’s how I tested it:

1. Put an ohm meter across one channel. If there’s a speaker on the other end of the wire, you’ll get 2 or 4 ohms. If it’s the input to an amplifier it will be much higher.

2. Take a line output from a boom box or something old/cheap. Feed this into one channel in the car. If it comes through the car it’s a line level input. If it doesn’t it might be speaker after all - check impedence again. Note: for this to work you need to make sure the power amp is on. Per the wiring above, apply 12v to pin 5 Blue/White Pwr Amp per the above wiring, or leave the OEM head unit in place, powered on, and just disconnect the audio connector to test line level inputs.

Note that Benz does not use a shielded/coax cable for the line level. It’s twisted pair. My installed picked up alternator whine which at first I blamed on the twisted pair, but I did some research and found that coax is no more immune to interference. I solved the whine with a pair of isloating transformers.

I just read something that put me at a screaching halt. I was told that I should not run the D3 or Z2 with the 2ohm wire and speakers that are stock in the car. Do you agree with that? If this is true, can I just purchase 4ohm speakers and wire and install?

I recall that Mercedes has long used CANBus ( http://en.wikipedia.org/wiki/Controller_Area_Network ) to link various components, and I am fairly sure the steering wheel stuff uses it. FYI Mercedes from 2003 onwards also uses a fiberoptic network for other purposes, and this is not to be confused with CANBus.

Since CANBus is standard I’m fairly sure you can get an adapter. I don’t have easy access to my D3 manuals but some Googling on ‘pioneer canbus’ and similar gets me to:

http://www.pioneer.eu/files/pdf/HardWiredAdaptersChart.pdf

Pioneer says that third part adapters are available, and they point to soundgate.com.

That site might have the right thing (and it’s definitely useful in that it decodes VSS, reverse and parking brake signals from CANBus, so it would ease installation) but it doesn’t specifically mention audio controls.

A little further digging gets me to http://www.service.pioneer-eur.com/peeservice/instrmanuals.nsf/0/98C26B508040CC4FC1256FA40031F72F/$File/CA-R-PI.131.pdf

which perhaps is the right thing, though might be available in Europe only. I’m sure you can find someone who will ship it.

This seems to confirm my theory:

http://avic411.com/forum/viewtopic.php?t=6562&highlight=carpi+131

Find someone selling a CA-R-PI.131 and you should be OK.

Note: I know nothing of this adapter except what I culled from Google over the past 15 minutes. If you buy one and it gives you cancer, I’m not to blame.

Thanks,

Howard

any differences installing the Z2 in a clk320?

I think indeed it’s a Seavo.

Lisa and I have decided to try an upright tandem. We have upright road bikes and have no problems with comfort, so we’ll see how that goes.

BTW, I’m actually a Brit. Lived in California since ‘92

However, given your transport problem you might want to look at the Barcroft Columbia which was where I was heading until recently because it’s very compact (even more so with the S&S couplings) You can Google both Rans and Barcroft.

But recently we’ve seen the Rans Feet forward bikes including their Dynamik Duo tandem and that opens up a completely new horizon. Our priority is comfort (especially in the hands and crotch) and equalising our strength rather than performance.

You have the good fortune to live in the USA where there is a good choice of such bikes, in Europe they are less common and less well developed.

best wishes from Sheffield England
Chris