Operation CHARM: Car repair manuals for everyone.
Manuals through 2025 now available!

Our trusted friends have launched a new website named LEMON, which has newer manuals. It also contains all the CHARM manuals.

LEMON is the spiritual successor to CHARM, I recommend you try it!

Link: lemon-manuals.la or lemon-manuals.org.ua

(Some people have issue connecting. LEMON is investigating. For now, use Firefox or change your DNS server)

Or, hide this message: temporarily or permanently

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.