In the Limo, we hace a Clarion (Denso) Sat Nav unit fitted.
It is connected to the in dash display. It has a satelite sensor on the dash. A VSS is fitted.
We bought it wholesale with no-one to fit it. Worked out pretty good price along with all the other Clarion gear.
It was fitted by an auto elec who followed all of the fitting instructions. It appears to be fitted correctly and sensing the VSS and the unit works,
except for some calibration issues. It wont follow on screen the road you are on, and when you stop it jumps back to the correct position.
The auto elec cannot help, and he said from the start he is not experienced in calibration of Sat Nav units. OK
We've rung a few audio places and they are not really willing to help as they didn't sell or fit the unit.
At the end of the day we want to pay someone money to get it right. Does anyone know of a committed, experienced, knowledgable person who can do the
job?
Any audio forums that you recommend to proceed further with this?
You could try posting your question here:
http://www.caraudioaustralia.com/forums/index.php?s=212670685692c10dcda971d3a...
I've found some very helpful advice on audio questions at these forums. Perhaps you might have some luck with Sat Nav queries too 
Pete, seeing I am a fellow EH lover.. 
I would love to have a look at
the sat nav for you. I cannot gaurantee whether I can fix this (as got out of audio industry before sat nav became big) but I am sure I could ahve a
look at least. do you have some model numbers for me to do some education on. I will try and speak to my clarion contact as well. and see what he
can shead on teh topic for you as well. Do not think the shopping list, of audio stuff is on teh website so if you could give me a list (either here
or email/u2u) I will start the tracing.
Cheers
Any ideas anyone? This thing is still not calibrated. Need help here.
try ringing Jon at auto-fidelity(don't have his no. on me)
he should be able to point you in the right direction.
tell him" mark, who used to work at porsche" ,sent you.