1991 Toyota MR2 Car Stereo Radio Wiring Diagram Whether your an expert Toyota electronics installer or a novice Toyota enthusiast with a 1991 Toyota MR2, a car stereo wiring diagram can save yourself a lot of time. One of the most time consuming tasks with installing an after market car stereo, car radio, car speakers, car amplifier, car navigation or any car electronics is identifying the correct color wires for a 1991 Toyota MR2. MKII Toyota MR2 Audio Installation How-To Guide MKII Toyota MR2 Audio Installation How-To Guide . This page gives the details of a DIY aftermarket stereo installation in a MKII Toyota MR2. The installation is performed in a 1991 MR2 with the stock "Premium" system, but a lot of the information here is applicable to all MKIIs.