Wouldn't the flashing top switch light while driving (before I replaced the CLP) indicate the PTCM is working? It was trying to notify me that something was wrong when it couldn't communicate with the CLP...? I'll still try out grounding the switch wiring to see if that does anything, but the PTCM is also above the trunk deck and there was only an inch or two of water in the right well of the trunk where the CLP is located (left well was dry as was the carpeted deck floor).