Is that the Impala one? I'm somewhat sure that's not the layout on my son's GTP.

Credit to Bizz on the STL board for this:

switch connections:

Pin
Wire Color
Circuit No.
Function

A
BRN
165
Power Window Motor Left Front Down

B
TAN
167
Power Window Master Switch Right Front Down Signal

C
--
--
Not Used

D
GRY
8
Instrument Panel Lamp Supply Voltage - 1

E
DK BLU
164
Power Window Motor Left Front Up

F
LT BLU
166
Power Window Master Switch Right Front Up Signal

G
BLK
750
Ground

H
YEL
143
Accessory Voltage


As I recall, the A-D ones seem to follow with the one I was looking at last night.