A/C Signal: Testing and Inspection

PREPARATION
Connect the special service tools (SST) to the powertrain control module engine (PCME).

SST Engine Signal Monitor-49 9200 162 And Harness Adapter-49 G018 903:

1. Connect the SST engine signal monitor between the PCME and the vehicle's PCME connector by using the SST adapter harness.

SST Sheet Overlay-49 G018 904:

2. Place the SST engine signal sheet overlay on the SST engine signal monitor.
3. Turn ignition switch ON. Turn blower switch ON.
4. Measure voltage at terminal 1Q.

Condition:--Air Conditioning Sensor (A/C switch) ON.
Voltage:--Below 2.5 Volts.

Condition:--Air Conditioning Sensor (A/C switch) OFF.
Voltage:--Battery voltage.

View: A/C Signal Path Diagram:

If readings are not as shown then inspect refrigerant pressure switch, thermoswitch, and wiring between PCME terminal 1Q (BR wire) and heater control unit terminal (G wire) from Air Conditioning Sensor.