What P0748 usually means
P0748 is the explicit electrical version of the PCS A cluster. It tells you the transmission controller has lost confidence in the circuit itself, not just in the shift feel that results. That makes the diagnostic order much cleaner: prove the connector, harness, internal wiring, shared feeds, grounds, and solenoid resistance before assuming line pressure is wrong because of mechanical wear alone. It is a strong indexing page because the intent is specific and it connects cleanly into the existing transmission electrical graph.