986 Speedometer Signal for the Radio
 

On the Becker CDR-220 Radio, the Pin1 of the Plug A receive a signal from the Instrument Cluster to say the Radio what speed the car goes so it can adapt the volume..

Does anyone know what kind of signal is received by the Radio? is it a voltage? is it a resistance?.. and between what values is it travelling?

Thanks :)

You could just put a volt meter (DMM) on it and find out exactly. Could also be a pulse though...post the results?

Regards, PK

Yes, I could 'just'.. if I had the car.. :P I just have the Radio.. I'm wirring a CDR-220 radio in my Sched.. ;)
No point of trying this on my 987, the radio system is completely different. and I don't feel like taking the dash appart.. :P

But I asked to a buddy who is specialised in Car Electronic, and he told me that usually the VSS (Vehicule speed signal) is Digital (Hall Effect), he din't know if there was a standard. Unfortunally, he's specialised in Toyota/Nissan/hyunday, not Porsches.. so he could'nt help me more than that :P

I was thinking I could 'fake' the Vehicule Speed Signal input of the radio (if it was a voltage with a reostat) to add myself a 'remote volume control', but I guess I'm gonna pass my turn on that one.. ;)

I wish my headunit did this. I would pay for a unit that knows when the top is up or down, when the windows are up or down and my speed and took this all into consideration for the volume.

The Stock radio headunit of your boxster did this, the CDR-220 and the CR-210 had a volume auto-adjustement to match the speed of the car.. but Honestly, for what I remember of the tree years with my 99 Boxster. Its not doing it very well.. the sound was changing randomly it was very weird and unplesant.. and I just ended up preferring disabling that feature and controlling it manually...

But, in the 987, they REALLY improved that.. I have the boss Sound System in my 06 Boxster S, and It does it very well.. It adapt itself to the speed, and the noise in the car (yes there is a microphone to help the radio to auto-adjust), it also got a different mapping when you got the top up/down (you can hear the radio switch when you clip/unclip the soft top), I need to say, it's a very nice feature.. :)