STEP 1. Check the circuit at ECM harness side connector.
(1) Disconnect the ECM connectors and measure at the harness side.
(2) Turn the ignition switch to the "ON" position.
(3) Measure the voltage between terminal AC/R and ground.- Voltage should be battery positive voltage.
(4) Using a jumper wire, connect terminal AC/R to ground.- A/C compressor clutch relay should turn "ON".
(5) Turn the ignition switch to the "LOCK" (OFF) position.
Is the voltage and A/C compressor relay condition normal?
Replace the ECM (Refer to Removal and Installation ). Then confirm that the malfunction symptom is eliminated. : Refer to GROUP 55, Automatic A/C Diagnosis - Introduction . Then confirm that the malfunction symptom is eliminated.