chicagoandy Posted January 4, 2012 Report Share Posted January 4, 2012 During my install, I couldn't find the speed wire on my 2007 Highlander, so I skipped it - leaving it unconnected. Everything seems to work just fine. What's the purpose of the vss speed wire? _Am Quote Link to post Share on other sites
steve6534 Posted January 5, 2012 Report Share Posted January 5, 2012 During my install, I couldn't find the speed wire on my 2007 Highlander, so I skipped it - leaving it unconnected. Everything seems to work just fine. What's the purpose of the vss speed wire? _Am As long as you always have GPS signal it doesn't serve a purpose. If you do lose GPS (tall buildings, tunnels, etc) the VSS is used in conjunction with the internal gyro and compass to perform dead reckoning navigation. Quote Link to post Share on other sites
zx6rrdan Posted January 5, 2012 Report Share Posted January 5, 2012 The unit is 3D GPS and is always using the GPS, VSS/Backup wire signal plus accelerometer to do extremely accurate mapping. Look on here and you'll find people that didn't connect vss and backup wire saying the GPS isn't accurate which sorta makes sense if one of the signals is always saying the speed is 0. Quote Link to post Share on other sites
LS3 MN6 Posted April 17, 2012 Report Share Posted April 17, 2012 VSS is needed for dead rekoning and is used as a plausability check for the GPS. Quote Link to post Share on other sites
Elemino Posted April 18, 2012 Report Share Posted April 18, 2012 The unit is 3D GPS and is always using the GPS, VSS/Backup wire signal plus accelerometer to do extremely accurate mapping. Look on here and you'll find people that didn't connect vss and backup wire saying the GPS isn't accurate which sorta makes sense if one of the signals is always saying the speed is 0. So you're saying not having the reverse signal is why my Navigation is always off a bit, and why it hasn't made any progress on 3D calibration? I thought the wire was only for the reverse camera. I haven't installed one yet, so I never connected the wire. Quote Link to post Share on other sites
RonS Posted April 18, 2012 Report Share Posted April 18, 2012 No, the backup signal is also used in conjunction with VSS and rotation sensor, to dead-recon compute all motion. Without a B/U signal, all VSS tics are interpreted by the HU as forward motion, which doubles the error. However, I also didn't install the B/U wire, and I don't think it changes much (unless you drive in reverse a lot). Once you get a good GPS fix, i doubt it matters. Quote Link to post Share on other sites
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