So I did a aftermarket Pioneer AVIC-Z150BH installation on 2003 Acura CL-S 6 MT, tapped into the vehicle speed sensor(VSS) blu/wht wire at the ECU as done in actory GPS installations......... everything seems to work, except sometimes the vss signal goes undetected by the GPS. I know its hook up correctly because sometimes it does works, as demonstrated by the NON-ZERO pulse signal that can be seen as the vehicle move, the accuracy in GPS tracking that ensues, shown under System Setting --->connection menu. Other times, when it does not work(meaning a pulse signal of 0 is depicted while the vehicle is in motion) the map lags and current locations become grossly inaccurate. The speedometer which also receives this vss signal amazingly seems to work 100% of the time with no delayed effects. Has anyone seem to have similar problem...if so can you offer insights and possible solutions...As you can tell this is extremely FRUSTRATING to have a system that works sometimes...

 

sounds like a bad connection or faulty wiring as most intermittent issues are. I would double check you wire connections especially where you tapped in to the PCM harness! Maybe use a volt meter to see the signal coming from VSS and wiggle the wire around to see if there is a bad connection.