Inspection Procedure

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.

Check voltage between terminal PRE of ECM and body ground.
PREPARATION:

Install the manifold gauge set.

CHECK:
1. Turn ignition switch to ON.
2. Check voltage between terminal PRE of ECM connector and body ground when refrigerant pressure is changed.
OK:

The voltage changes with refrigerant pressure, as shown in the diagram below.

Fig 1: Checking Voltage Between Terminal PRE Of ECM Connector And Body Ground
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

Fig 2: Refrigerant Pressure Voltage Changes Diagram
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
1. OK: Proceed to next circuit inspection shown on problem symptoms table (See PROBLEM SYMPTOMS TABLE ).
2. NG: Go to next step.
Check pressure switch.
PREPARATION:

Disconnect pressure switch connector.

CHECK:
1. Turn ignition switch to ON.
2. Check continuity between terminals 1 and 4 of pressure switch when refrigerant pressure is changed.
OK:

The continuity changes with refrigerant pressure as shown below.

Fig 3: Checking Pressure Switch
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

Fig 4: Refrigerant Pressure Continuity Conditions
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
1. NG: Repair or replace harness or connector
2. OK: Go to next step.
Check harness and connector between ECM and pressure switch, pressure switch and body ground (INSPECTION, Connectors, Terminal pins, Wiring Harness (Open or Short Circuits)).
1. NG: Repair or replace harness or connector.
2. OK: Go to next step.
Check harness and connector between ECM and A/C amplifier. (INSPECTION, Connectors, Terminal pins, Wiring Harness (Open or Short Circuits))
1. NG: Repair or replace harness or connector.
2. OK: Check and replace ECM.