1999 rear defroster wiring

[sparky19692]

I just installed a remote Starter in our 1999 Grand Caravan sport.
I was able to get everything working. however there is a PCB behind the heater controls,
and I can not find a wiring diagam for the momentary push button of the rear defroster on the PCB.
Does anyone know what wire color it would be leaving the PCB and if so can I simply splice
in a momentary (-) or 0 vdc to this wire.
Thanks in advance.