Circuit Description

WARNING: This page is about a different car, the 2003 Lexus IS 300. However, it is still accessible from the selected car via links, so may be relevant.

The pressure switch sends the appropriate signals to the ECM when the A/C refrigerant pressure drops too low or rises too high. When the ECM receives these signals, it outputs signals via the ECM to switch OFF the compressor relay and turns the magnetic clutch OFF.

DTC B1423 TROUBLE DETECTION REFERENCE

DTC No.	Detection Item	Trouble Area
B1423	Open in pressure sensor circuit. Abnormal refrigerant pressure. below 181 kPa (2.0 kg/cm² , 28 psi) over 3,140 kPa (32.0 kgf/cm² , 455 psi)	Pressure switch. Harness or connector between pressure switch and ECM. Harness or connector ECM and A/C amplifier. Refrigerant pipe line. ECM.