Originally Posted by theoutbackdream
Do the 08 2.5is have similar connection diagram as the 2012 wrx?
2012-up Imprezas (not WRX or STI) with a non
-nav factory head unit still use the same 20-pin harness for power/speakers/SWCs/etc. as previous years. Crosstrek also. There are a couple of minor differences (which mostly don't matter when installing an aftermarket HU):
* The new Imprezas and Crosstreks dropped the CAN data bus. That only matters if you're trying to transplant OEM HUs across different models/years.
* The new Imprezas and Crosstreks now have a pin for the illumination "bright" mode (night illumination dimness cancellation - 'NIDC'). Pin 11 (formerly one of the CAN pins).
* The new Imprezas and Crosstreks have Vehicle Speed Signal (VSS) on pin 19. That is used for the speed-sensitive volume feature on the OEM HU (as well as locking out functions while you're moving). A few aftermarket navigation HUs can use that signal to improve position tracking. I can include an extra wire for VSS on my harness if you request it.
2011-2013 WRX and STI, and 2011 Impreza/OBS are all still the same (they have CAN bus, and no pins for VSS or bright mode -- they use CAN bus for the speed volume and NIDC features).