Mr12Volt P800PO installation – 996.2 CDR-23 with Bose/MOST

I thought I’d share my initial experience of fitting a Mr12Volt P800PO module to my 996.2, which has the CDR-23 and Bose/MOST system. The module adds Bluetooth audio streaming and hands-free calling while retaining the original head unit. My car didn’t have a CD changer, but the supplying dealer, RPM Specialist Cars, was able to code the CD-changer function before I fitted the Mr12Volt unit. Installation wasn’t entirely straightforward. There appeared to be a tolerance issue with the power connector: power was reaching the plug, but the terminals weren’t making reliable contact with the module when connected. The module also doesn’t complete the fibre-optic loop unless it has power, which made diagnosing the problem slightly more challenging. Once that was resolved, the CDR-23 initially exhibited some slightly odd behaviour, although it subsequently seemed to sort itself out. Pairing my phone by Bluetooth was easy enough, but it took a little experimentation before music would play consistently through the stereo. The CDR-23 doesn’t display artist or track information; it simply shows Track 1, Track 2 and so on. You can skip backwards and forwards between tracks, and it appears that calls can be answered using the right-hand knob. I still need to spend some time balancing the different volume levels for Bluetooth streaming, calls and the radio/CD. Touch wood, it now seems to be working. Earlier today I briefly had no audio at all, although I’m not convinced that was caused by the Mr12Volt unit. Turning the car off, locking and unlocking it, and then restarting restored everything. I’ll see how it performs over the next few weeks and report back if anything changes. My initial impression is that, much as I like the centre-console delete and retaining the original CDR-23, I do miss CarPlay—and I have very little patience for temperamental interfaces!

How did you hook up the box to power? I installed one of these a couple months back and it was very temperamental using the no solder pin bits which screw onto the existing wiring. In case it’s helpful, after some freestyling my solution was as follows: I removed the positive and ground wires from the connector which fits into the back of the PCM unit. Then I stripped back the sheath on the existing wires around 1.5cm, soldered each Mr12V wire to its corresponding PCM wire, and used heatshrink to re-add the sheath. Also if you haven’t already, make sure you use some 3M Velcro tape to hold the unit in place so it’s not shaking around inside the dash. Imo Mr12Volt has missed a trick by not encouraging buyers to do the soldering themselves. It now works flawlessly with no interference, and I have track info, forward/back functionality as well as the name of the connected device showing up in the head unit (see pic). At some point I might install the mic as well although I don’t tend to make/receive calls while driving. I’m average with a soldering iron and the whole thing took me 45min. The most finicky part is removing the PCM cables from their connector which requires a needle to depress the toggle inside each connector pinhole. Make sure you don’t force them out (I imagine a broken toggle is a royal pain to sort out after).

Hi there, I think your store may have been a little more complicated than mine as I was just working with the CDR 23 rather than a PCCM. Power taken from the back of the fuse box. I think with the CDR-23 I’m limited as to what it will display, so my assumption is that the stereo can only handle “track 1”, “track 2” from the CD Changer inputs. I’ve just popped the microphone on top of the steering column shroud, that bit was very straightforward, fed the wire up from the gap below the steering column, to the area behind the HU, then tidied it up a bit. I have aspirations of trying to use a two wire factory mic, but that’s a future task.