So with the switch in and measuring at the connection
Tan?W 2.7 Volts Depress button 1.24 Volts
Red/Yellow 1.2 Volts Depress button no change
White/Green 12 volt Depress 0 Volt Depress back to 12 Volts
This was with out the 17 fuse which metered .5 volts on what should be the dead side.
Measured at the switch with out the switch or fuse
White/Green no volts
Red/Yellow 1.18 Volts
Tan/White 2.7 Volts
It seems to me that the PCM could be supplying voltage through the check engine light circuit to Red/Yellow and, am I wrong, but there should be no voltage at the Tan/White at all.