I pulled the R3 and R4 plugs from the stereo. The first thing I noticed is that they are on the left side of the stereo with R3 to the far left. The diagram of the locations in the wiring diagram I downloaded from TIS show them on the right side with R3 on the far right. But here is the important question. R4 has an extra wire not shown on the diagram. It is in pin position 5 and is White/Black. Pin 6 next to it is Yellow and matches the diagram for RL- speaker... What does it do? I may have to remake my harness now as I did not include it in my Y harness for my stereo upgrade. P.S. According to the replacement "Y" harness from Metra part # 71-1761 it is a "grounding dimmer". P.S.S. Found another wire not on the diagram. It is on R3 and is pin #10 and is Dark Green (not the Light Green pin #1 which is FR+ speaker). On the metra cable replacement it is marked "Dimmer" Any idea what these two wires actually are and if they are needed as part of the harness? [Broken External Image]:http://www.scubadivervideo.com/images/Prius/wireda.gif
R4-5 and R3-10 are both labled as Illumination (Rheostat) signal and with parking lights or headlights on it should measure 10 -14v to body ground
