Found it. Poking around under the car and located it in the rear of the vehicle between the muffler and the differential. Unhooked it and tried car. Same tpms malfunction. Opened the sealed box. Found corrosion present on the circuit board. Seems there is a vent that lets moisture in. Cleaned up the circuit board with alcohol and a toothbrush. Still same fault. Took it for a drive, all other faults cleared but still tpms malfunction.