ESOF question???
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Freshman User
Joined: Dec 2007
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From: Toccoa, GA
ESOF question???
My ESOF doesn't automatically shift to 4WD when I engage it. I have to get out and lock the hubs for it to work. Would this be due to the vacuum lines and if so, how do I check/repair?
Freshman User
Joined: Apr 2006
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From: South Chicago Burbs
Pull the line off the hubs one at a time and verify with a vac gauge that you are getting vacuum to the hubs. If you are, it's inside the hub. If you're not, backtrack up the system. This time of year we see a lot of ice in lines.
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Joined: Mar 2007
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From: ct
I checked my vacuum lines to my hubs and one was rotted. So I took the nipple off the hub and cleaned it with PB blaster hooked up a new vacuum line and Still there was no vacuum. I then did a search on this forum and found out the PVH solenoid likes to crap the bed allot. I did the test they recommended but mine passed. So said hell with it and bought a PVH solenoid and it fixed my problem.
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Freshman User
Joined: Dec 2007
Posts: 29
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From: Toccoa, GA
I had my heater blowing out of the panel vent and when I shifted to 4Hi, the air started blowing from the defrost. It wouldn't change back even when I turned the 4WD off and switch the air flow. I had to turn off my truck before it went back to normal. Would this have something to do with the vacuum lines?
Posting Guru
Joined: Dec 2006
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From: NorCal
Yes, if you have a vacuum leak somewhere it will cause the heater to only blow out the defrost vents.
The hub seals are a common place for a vacuum leak to happen. You can test for a hub seal leak by pulling off the vacuum line that goes into the backside of each hub and plugging it off, then try putting the truck in 4wd to see if your heater vents still revert to the defrost setting.
The hub seals are a common place for a vacuum leak to happen. You can test for a hub seal leak by pulling off the vacuum line that goes into the backside of each hub and plugging it off, then try putting the truck in 4wd to see if your heater vents still revert to the defrost setting.
