Explanation - ECM detected the leak detection pump swith did change after solenoid was energized
Probable Cause 1 - Leak detection pump defective 2 - Open or shorted circuit condition 3 - Solenoid defective
Its the little round thing near a green valve cover on the passenger fire wall. The FSM doesn't give me any more information on testing other than to replace it.
I would first check the evap lines on the driverside firewall where they change direction and go toward the tank, the 90 degree connecting hoses tend crack and leak. If the hoses are good you need to simply just replace the detection pump.