In the FSM, under "diagnostics > Active Height .... > Terminals of ECU" you can find all the voltage values for the different inputs to the ecu. And further on you find the fault finding procedure specific for each sensor or input signal.
Better check the front gate solenoid first then. If you unplug 5-pin plug of the valve assembly, you can measure continuity of each of the four solenoids. Pin # 2, Blue w Yellow, is the common, and each of the other four pins should have continuity (low ohm) to # 2. Front gate is pin 1, Violet.
When you unplug the valve assembly, you might find that the problem is in the plug, although the t0yota plugs normally keep up very well.
You can find the same signals/leads up at the ahc ecu, at plug S9, pin 24 as common, 7 is front gate, the other three at pins 8, 20 and 21. Same colours as in the 5-pin plug at the valve assembly.