Throttle Full Open Switch: Description and Operation

The Variable Load Control Module (VLCM) does not use a separate output circuit for Wide Open A/C Cut-off (WAC). Instead, the A/C clutch control information is included in the two way communication between the VLCM and the Powertrain Control Module (PCM). When A/C is requested the PCM will verify that A/C operation is desirable (example: engine not cranking or overheated, not at WOT, etc.). If A/C operation is desirable, the PCM will send a message to the VLCM to turn on the A/C clutch. The VLCM sends messages to the PCM through the BUS+ and BUS- circuits indicating the A/C status (On or Off), and if any A/C circuit faults are detected.