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Is there somewhere I can get a wiring diagram for the Matsushita unit?

It is best to use a Wiring Adapter for a fool proof Install......

Here is what I show for wire colors

Constant 12V+ Blue/Yellow or Blue/Black
Switched 12V+ Gray
Ground Brown
Illumination Green
Antenna Trigger Black/Red
Front Speakers;
Left Front (+) Pink
Left Front (-) Purple
Right Front (+) Light Green
Right Front (-) Blue
Rear Speakers ;
Left Rear (+) Black
Left Rear (-) Yellow
Right Rear (+) Red
Right Rear (-) White

That's the same info I have that led to my problem. Seems that the stereo color codes are different than the Toyota codes

sorry.........I can only go by the info you posted........

The Toyota harness doesn't have the blue/yellow or blue/black for constant - it's blue and the acc isn't gray, it's white/black

That is from the Service Manual

That is why a Wiring Adapter is best, XXXXX XXXXX is color for color

Schematic:

B = Black
BR = Brown
G = Green
GR = Gray
L = Blue
LG = Light Green
0 = Orange
P = Pink
R = Red
V = Violet
W = White
Y = Yellow