Hublock Engagement/Disengagement Time

WARNING: This page is about a different car, the 2005 Ford Pickup, 2005 Ford F550 Super Duty, 2005 Ford F450 Super Duty, and 2005 Ford Cab & Chassis. However, it is still accessible from the selected car via links, so may be relevant.

With the hublock dials in the AUTO position, switching the instrument panel mode selector switch (MSS) to 4x4 HIGH or 4x4 LOW results in the high vacuum level being applied to the hublocks, which lasts for at least 51 seconds (including a venting cycle). The hublocks should engage during this time through the spring mechanism. Switching the MSS to 4x2 less than 51 seconds after the MSS had been switched to 4x4 HIGH or 4x4 LOW will not interrupt the high vacuum level; instead, the lower vacuum level will be applied after the high vacuum level cycle is completed.

With the hublock dials in the AUTO position, switching the MSS to 2WD results in the lower vacuum level being applied to the hublocks, which lasts for about 15 seconds. However, the actual time required for the hublocks to disengage by spring force can vary considerably due to the effects of driveline wind-up; road bumps, vehicle speed, acceleration cycles or momentary reversal of direction can assist this process. Switching the MSS to 4x4 HIGH or 4x4 LOW always overrides the lower vacuum level cycle and results in a immediate high vacuum level and in locking of the hublocks.