Pulse Vacuum Hublock Solenoid Problem?
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Pulse Vacuum Hublock Solenoid Problem?
My 4wd stopped working in my 2003 F250 about a month after I took it to the dealership for a Diesel PCM update. I'm trying to figure out if the PCM controls the Pulse Vacuum Hublock Solenoid (PVH) - does anyone know if this is the case?
If the PVH is not controlled by the PCM, do you know what controls it? My 4x4 system doesn't work properly, but I've ruled out a bit of hardware. The following is a short list of things that I know about my problem:
-My Vaccum lines aren't leaking
-All fuses labeled "4x4" are fine (there are 3 of them, one is a fusible link.)
-The Transfer case successfully shifts into 4x4 mode - I know this because I can re-route some vacuum lines, and lock the locking hubs. When I do this, all four wheels will spin in the snow, and I actually have some traction. This tells me that mechanically, everything does actually work, but there is never a vacuum signal sent to the front hubs to lock them.
- Hooking a vacuum line up to the output line of the PVH shows that the PVH does not turn on when 4x4 is selected on the ESOF switch.
- When probing the 3 pin connector from the wiring harness to the PVH, I can find (from left to right when looking at the wiring harness connector) ground, and a constant +12V, switched. The third wire doesn't have any reading, at all. I suspect this is supposed to tell the PVH to turn on and off? The readings on these pins never change. When I have someone flip the 4x4 switch, nothing happens. This goes in line with the no-vacuum reading from the output of the PVH.
Does anyone know how I can bench test the PVH? I don't have a truck manual, but I suspect that pin3 is supposed to carry some momentary signal or something to tell the PVH to turn on. Any help with this issue would be greatly appreciated. Thanks :-)
If the PVH is not controlled by the PCM, do you know what controls it? My 4x4 system doesn't work properly, but I've ruled out a bit of hardware. The following is a short list of things that I know about my problem:
-My Vaccum lines aren't leaking
-All fuses labeled "4x4" are fine (there are 3 of them, one is a fusible link.)
-The Transfer case successfully shifts into 4x4 mode - I know this because I can re-route some vacuum lines, and lock the locking hubs. When I do this, all four wheels will spin in the snow, and I actually have some traction. This tells me that mechanically, everything does actually work, but there is never a vacuum signal sent to the front hubs to lock them.
- Hooking a vacuum line up to the output line of the PVH shows that the PVH does not turn on when 4x4 is selected on the ESOF switch.
- When probing the 3 pin connector from the wiring harness to the PVH, I can find (from left to right when looking at the wiring harness connector) ground, and a constant +12V, switched. The third wire doesn't have any reading, at all. I suspect this is supposed to tell the PVH to turn on and off? The readings on these pins never change. When I have someone flip the 4x4 switch, nothing happens. This goes in line with the no-vacuum reading from the output of the PVH.
Does anyone know how I can bench test the PVH? I don't have a truck manual, but I suspect that pin3 is supposed to carry some momentary signal or something to tell the PVH to turn on. Any help with this issue would be greatly appreciated. Thanks :-)
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