4x4 vacuum switch problem?
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Fleet Mechanic
Joined: Apr 2011
Posts: 1,441
Likes: 6
From: Marseilles IL
4x4 vacuum switch problem?
My 2000 auto 4x4 hubs are not locking. I replaced the line going to the driver side wheel. It looked like a soaker hose for watering the lawn. I turn the switch on the dash and the 4x4 light comes on the dash, the driveshaft locks in the transfercase, but no vacuum at the wheels. Checked the vacuum switch on the fender and it has vacuum going in but it is not switching vacuum. Now the questions! Is there a fuse that would control the vacuum switch separately from the 4x4 light? Anyone have a wireing diagram or advice how to test it further? Any help would be great! Thanks all in advance.
9 ECHO 1
Joined: Aug 2009
Posts: 12,467
Likes: 58
From: Missouri
You have a vacuum leak. I have an active thread on it. This thread has many different ways to diagnose it. Read this and see what you find:
https://www.ford-trucks.com/forums/1...-question.html
https://www.ford-trucks.com/forums/1...-question.html
Thread Starter
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Fleet Mechanic
Joined: Apr 2011
Posts: 1,441
Likes: 6
From: Marseilles IL
My vacuum switch is under the hood on the passenger firewall it has plenty of vacuum going into the switch butt nothing coming out. I think the switch is not getting it's signal voltage or ground. Or vacuum switch is bad! Not sure? I may have a vacuum leak after, Aka soaker soaker hose.
9 ECHO 1
Joined: Aug 2009
Posts: 12,467
Likes: 58
From: Missouri
Switch into 4x4 and run over to that side of the engine, if the motor is on, there is a leak after the pump. If the motor is NOT on, then get a test light and find out if there is a signal coming into the pump, if there is a signal coming in then the pump is bad.
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Fleet Mechanic
Joined: Apr 2011
Posts: 1,441
Likes: 6
From: Marseilles IL
I have a Vac Gage and I didn't check what's going into the switch butt it sucks good . I tested what's coming out and it's a big 0 no matter what. Think I need the wiring schematic to b able to test the wiring coming into the switch.
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Senior User
Joined: Mar 2007
Posts: 473
Likes: 3
From: Issaquah, WA
Sounds like the vac switch on the fender is shot. Had the same thing happen to me. $50 at the dealer.
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Junior User
Joined: Apr 2011
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From: Chandler
Wait what? Our trucks have auto locking 4x4 hubs? I thought my 2002 f350 was all manual, I got some rims that cover the hubs and I dread the next time I need 4x4 action I'll have to get out the allen wrench in the snow and go to work...
How do you check if your truck even has these?
How do you check if your truck even has these?
Thread Starter
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Fleet Mechanic
Joined: Apr 2011
Posts: 1,441
Likes: 6
From: Marseilles IL
Bitterbeard u can check by looking at your front wheels . You will have 3 lines instead of two going to each front wheel. One is your brake line, one is your abs line, and the other is the auto hub line. The auto hub line connects to a hose barb on the inside of the knuckle.
Junior User
Joined: Apr 2011
Posts: 52
Likes: 0
From: Chandler
Yep, I've got auto locking hubs. Mine look nowhere near as nice as Trey's, I think the previous owner used them to clean his boots off or something before getting into the truck. I'll need to tear them apart following Guzzle's walk through, once again thanks to FTE for the info!
9 ECHO 1
Joined: Aug 2009
Posts: 12,467
Likes: 58
From: Missouri
I posted an update to my thread.. I fixed the problem on mine. Pics included..
https://www.ford-trucks.com/forums/1...l#post10438226
https://www.ford-trucks.com/forums/1...l#post10438226
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