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Manual Override

WARNING: This page is about a different car, the 2012 Ford Pickup, 2012 Ford F550 Super Duty, 2012 Ford F450 Super Duty, and 2012 Ford Cab & Chassis. However, it is still accessible from the selected car via links, so may be relevant.

The CVHs have a manual override selector dial, which, when turned to the LOCK position, keeps the CVHs locked (via the dial) at all times, regardless of the position of the instrument panel MSS. (Always set both hublock dials to the same position. If the CVH dials are manually turned from the AUTO to the LOCK position, and vacuum is supplied to the CVHs (by switching the MSS from 2H (4X2) to 4H (4X4 high) or 4L (4X4 low), the CVHs are locked through the dial as well as through the internal spring mechanism. In this case, turning the CVH dials back to the AUTO position leaves the CVHs in (spring) locked mode until vacuum is removed from the CVHs (by switching the MSS from 4H or 4L to 2H). (This is not an issue if the CVH dials have been in the AUTO position and the MSS has been switched from 4H or 4L to 2H at least once.) The CVH should be left in the AUTO position for increased fuel economy.

ELECTRONIC SHIFT-ON-THE-FLY (ESOF) CONSTANT VACUUM HUBLOCK (CVH) OPERATION

CVH Operational State CVH Dial Switching Procedure
"Locked" Position - Manual Override Switch the CVH dial to LOCK
"Automatic" Operation via Electronic Shift-On-The-Fly (ESOF) Switch the CVH dial to AUTO