VSS wire (SCV) Speed Compensated Volume
 

CORRECTION: The below information that I was told, then posted is incorrect, at least with my 1999 FRC. The SCV wire coming from the existing bose plug is not a VSS wire. I hooked mine all up and when I ran the Nav program it would ask me to "check my speed sensor. So I looked up that message in one of my THREE how to manuals that came with the unit and it said to check my Speed Sensor. To make a long story short, I pulled it back out, took the dash cluster out and hooked it up to the Green/White wire. All works great!!! Now I just have to find time to read all the manuals! Sorry for the mis information!!


I just got back from my local radio tec. The VSS wire that has been eluding me during my Eclipse 5435 install is also in the 20 pin amp Bose plug that I unplugged from the original Bose radio. If your Bose radio is equipped with the (SCV) Speed Compensated Volume control, that is a VSS wire. That is how the Bose radio knows to turn up the volume. It also is green with a white strip. Much easier then the removing the front passenger wheel and inner fender well to get to the ECM or getting under the dash for the instrument cluster plug.

Yep, all Bose systems with automatic volume control (in the C6 GM calls it "Bose Audio Pilot") has the VSS wire going to the back of the HU, dark green with a white stripe. On the C6 w/Bose there are two dark green wires with white stripe on the 12 pin harness. One is at pin H and the other at pin D. The VSS wire is at pin D.
The easiest way to tell if a wire is in fact the VSS, simply put a multimeter to it. The VSS is an AC Pulse so you will notice the meter at a set position while the car is stopped and will "pulse" rapidly between 3 to 8 volts when the car is moving.

According to the pinouts in the C5 sticky, the dark green/white wire(pin 12) on the 20 pin plug is remore radio signal - right hand audio (with UZ6). Would this be the VSS wire???

:lurk:

No, pin 12, right audio signal on the 20 pin harness, is not the VSS wire and I'm not seeing a VSS wire in the schematics shown in the C5 FAQ. A dark green with white stripe wire at circuit 368 is typical for GM to put the right audio signal wire. However, I'm not seeing anything like a circuit 817 where the VSS would be (like in the C6). I know the C5 Bose systems had automatic volume control or Speed Compensated Sound, or whatever GM calls it, because I have it in my C5. However, I have never installed a NAV unit in my C5 so I never had the need to track it down.

I have already described in this thread how to check a wire to see if it is VSS so perhaps if you narrow down the wires you could check them using that method. I would also recommend pulling your HU and checking your harnesses yourself just in case they sneaked in an extra circuit and an extra dark green w/white stripe wire that doesn't show on those schematics. Like, for example, they aren't listing the Denso inputs in that schematic….just a thought.

If all else fails, at least you know you can tap the VSS wire at the instrument cluster harness. :leaving:

According to my notes, the VSS wire for the C5's is the dark/green with white stripe located at the instrument cluster, or at the PCM (passenger control module) located beneath the battery in the passenger side engine compartment area, red plug, pin 50.
Nomad is correct on how to test for the VSS wire. The VSS wire actually is the wire that sends the information picked up from the transmission speed pulse signal transmitted to the PCM and then onto the instrument cluster to show your speed on your speedometer. As far as where it interfaces with the radio for the speed compensated volume, we may be thinking about it the wrong way for the C5's. Without looking at the wiring schematics, many C5 owners have a hidden amp tuner box of some sort near the steering column under the dash. Perhaps the signal is sent from there to the radio via one of the wires in the gm radio harness that in turn activates the volume control in the radio itself. Just a thought... I don't know for sure on the C5... hope this helps!! :thumbs:

C6 Vss
 

Hey guys, your write ups have been great for the Nav systems...I have ordered the AVIC-D2 with the periferial GMCO, and I think I am prepared for the installation when it gets here, but still wanted to clear up the VSS issue. I have a 2006 C6 with the base stereo (not bose) and no on-star. Here are my questions:
1) I know where the ECM is, but there are several references to the Instrument Control Module to more easily acces the VSS...where is this module in the dash, and what pin and wire am I looking for?
2) This appears to be reference by Dave above, but the base system has the Speed Sensitive Volume Control...is there no VSS at the harness, like the Bose? It appears that Audio Dave thinks it is not there on the C5...how about the 2006 C6?
3) Kind of related...in the spot where Nomad installed the additional XM/IPOD adapter, I appear to have a stock amp I am not going to change out right now...Can you think of a good place to stick the IPOD adapter? Under the passenger seat?
Just trying to be prepared when it gets here...Thanks for your help in advance!