Security relay
Good idea but me thinks you can't get there from here. The RKE or remote keyless entry transmitter sends a signal to the CTM or central timer module which activates the headlight relay (also called the security relay) and the horn relay. And since it results in an on off on off sequence it wouldn't work anyway. I guess you could trigger a relay off the headlight circuit after the relay with a hold in feature and do it but you would need another switch to disable the circuit when you didn't need the heater and your neighbors would probably raise H@#%&* with you for honking the horn at 4:00 in the morning. bg