4x4 shift on the fly
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Elder User
Joined: Jul 2005
Posts: 659
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From: Berthoud, CO
4x4 shift on the fly
Gents,
My truck wont lock into 4x4 anymore. The other day, with just the key on, I flipped the 4x4 switch and listened. I heard a neeer click, neeeer click, it just kept repeating that sound. The vaccum pump didnt come on, but I have felt the air switch to the defrost when I have switched the 4x4 switch to 4x4 in the past. This sound like a vaccum pump issue, or more twoards the vaccum lines? The truck has 165k miles on it.
Thanks for any input.
My truck wont lock into 4x4 anymore. The other day, with just the key on, I flipped the 4x4 switch and listened. I heard a neeer click, neeeer click, it just kept repeating that sound. The vaccum pump didnt come on, but I have felt the air switch to the defrost when I have switched the 4x4 switch to 4x4 in the past. This sound like a vaccum pump issue, or more twoards the vaccum lines? The truck has 165k miles on it.
Thanks for any input.
Posting Guru
Joined: Mar 2007
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I had a similar problem happen to my trcuk. It ended up being the vaccum hoses on the top of the Ft steering knuckles. They dry rotted and where just hanging there. In case you are not sure where this is,you will find them by the FT shocks. If you apply pressure to the hoses,the one that collapses as you pinch them with your fingers is the vaccum hose you will want to inspect and replace if you find it damaged. I didn't see any damage to my hoses, but to the touch they were literaly falling apart in my hand. Well I replaced them both and I've never had anymore problems with my truck locking into 4x4. Hope this helps yah out. I do have pictures of the hoses in question, I just dont know how to post them here. I can send them via e-mail if you still need them. countrycar@hotmail.com Take care.Country
More Turbo
Joined: May 2006
Posts: 603
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From: Plano Texas
I'm having the same problem. Did you relace the lines all the way to the vacuum pump? I ordered two new steel braded lines that go about that connect into the other line but still have the problem of the air switching to defrost. I replaced the vacuum pump as well. I think im going to bypass the other lines as a test one at a time.
Posting Guru
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Elder User
Joined: Jun 2006
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From: Connecticut
Originally Posted by whitesdford
Gents,
My truck wont lock into 4x4 anymore. The other day, with just the key on, I flipped the 4x4 switch and listened. I heard a neeer click, neeeer click, it just kept repeating that sound. The vaccum pump didnt come on, but I have felt the air switch to the defrost when I have switched the 4x4 switch to 4x4 in the past. This sound like a vaccum pump issue, or more twoards the vaccum lines? The truck has 165k miles on it.
Thanks for any input.
My truck wont lock into 4x4 anymore. The other day, with just the key on, I flipped the 4x4 switch and listened. I heard a neeer click, neeeer click, it just kept repeating that sound. The vaccum pump didnt come on, but I have felt the air switch to the defrost when I have switched the 4x4 switch to 4x4 in the past. This sound like a vaccum pump issue, or more twoards the vaccum lines? The truck has 165k miles on it.
Thanks for any input.
You might want to check out the hub lock solenoid.I had this happen to me a few weeks ago.It cost me 40 bucks,but its fixed.I was not getting vac to the hubs either,but hvac system was also defaulting back to defrost.But its because mine was working,but not holding the vacuum.
Hope this helps.....
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More Turbo
Joined: May 2006
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From: Plano Texas
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Posting Guru
Joined: Mar 2007
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The mysterious source of vacuum for the 4x4 hubs and the HVAC dampers is a little pump located on the passenger side fender liner. There's a big plastic oval tank that sits just inboard of it with some tubes connecting the two. You can see the vacuum pump at the bottom of THIS PICTURE and the tank is at the lower left.Here's a picture of it:
PVH soleniod
PVH soleniod
Not a liberal...
Joined: Jul 2006
Posts: 6,635
Likes: 4
From: Cut & Shoot, Texas
If it is the leaking hoses then you should check this out. I replaced mine with these and everything works great now.
http://www.dieselsite.com/index.asp?...ROD&ProdID=348
http://www.dieselsite.com/index.asp?...ROD&ProdID=348
Posting Guru
Joined: Mar 2007
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Very Nice Scott. I wish I would have know about these before I did my hose replacement. I used a Silicone vaccum hose I found at Track Auto. Zip tied the ends and life is good. I still like the SS hose kit better though. AHH well I am only out about 4 bucks. Yeah I think I will spring for the SS Hose kit. Man I'm a laydown!! Thanks Scott. Take Care, Country.
Elder User
Joined: Jun 2006
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From: Connecticut
Originally Posted by Chance_Thomas
Is that above the vacuum pump?
Its on the inner fender,right behind the battery on the passenger side.Its bolted to the wall.It has 2 hoses and on connector with 3 wires going to it.
Elder User
Joined: Jun 2006
Posts: 613
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From: Connecticut
Originally Posted by Chance_Thomas
I'm having the same problem. Did you relace the lines all the way to the vacuum pump? I ordered two new steel braded lines that go about that connect into the other line but still have the problem of the air switching to defrost. I replaced the vacuum pump as well. I think im going to bypass the other lines as a test one at a time.
What i did,is pull both lines going to the hub off,not at the hub,but near the shock tower.I plugged them (don't remember with what).Then did the defrost test again.With the truck in 4x4.Happened again.So i pulled one of the hoses off at the hub solenoid,(The one that goes to the hubs)pluged that hose.Still went to the defrost and the pump kept on running.So i pulled the feed hose off of the solenoid and held the end of it with my thumb,pump turned off.
Thats when i figured out what the problem was.
Junior User
Joined: Dec 2003
Posts: 88
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Well to bring up a older thread. I am having the 4x4 issue as well. I have tried:
Turning the switch on the dash to both 4wd high and low. I can hear the transfer case switch into 4wd, plus the case does switch into low.
My A/C does not switch to defrost when the 4wd switch is engaged.
Where too now?
Turning the switch on the dash to both 4wd high and low. I can hear the transfer case switch into 4wd, plus the case does switch into low.
My A/C does not switch to defrost when the 4wd switch is engaged.
Where too now?