4x4 engages by itself!?!?!?!
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Freshman User
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4x4 engages by itself!?!?!?!
First of all thanks for all the help on my previous posts.
Now, originally my HVAC controls were not working and my 4x4 was not engaging. I replace the vac lined from the hubs (quite rotted) to the hard line in the wheel well. Did not fix problem. By the way the vac pump was running and not turning off. I pulled the vac line off of the PVH solenoid and I pinched off the line coming from the pump and the HVAC controls started to work and the pump would turn off after a couple of minutes. I replaced the PVH solenoid (it had a pretty bad crack) and the HVAC controls continue to work but the 4x4 is engaging and disengaging all by itself.
What am I missing?
Now, originally my HVAC controls were not working and my 4x4 was not engaging. I replace the vac lined from the hubs (quite rotted) to the hard line in the wheel well. Did not fix problem. By the way the vac pump was running and not turning off. I pulled the vac line off of the PVH solenoid and I pinched off the line coming from the pump and the HVAC controls started to work and the pump would turn off after a couple of minutes. I replaced the PVH solenoid (it had a pretty bad crack) and the HVAC controls continue to work but the 4x4 is engaging and disengaging all by itself.
What am I missing?
Elder User
Joined: Jun 2007
Posts: 705
Likes: 1
From: Sandia Park, NM
Sounds like it might be a short from the switch. Try pulling the dash switch and ringing out the switch and the wiring. Something is sending a false signal that you are selecting 4wd. Are the hubs locking, or the shafts engaging, or both? Are you seeing the 4X4 light or how do you know that it is engaging/disengaging itself?
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Freshman User
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Thanks, I am going the check the switch this week. And it is the 4x4 light in the lower right of the instrument panel that is turning on and off. Also I can feel and hear it engage. I will post back once I check the switch.
Elder User
Joined: Jun 2007
Posts: 705
Likes: 1
From: Sandia Park, NM
Please let me know what you find. My 4X4 light went out this weekend to never come back on. I suspect it may be a bad solenoid or the switch. I would say loose connection on your solenoid, but if the switch is set to 2X you should not see that light come on.
Elder User
Joined: Jun 2007
Posts: 705
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From: Sandia Park, NM
So here's what I found on my truck last night. No 4x4 light on dash in any position of the switch, no vac pump running, no power to selector switch. Checked all fuses, good. Tapped on vac pump and it started working. Got under truck to find that the clip on the "feedback" plug was broken allowing the connector to back out. Pushed the connector in with KOEO and nothing. Pushed the connector in with KOER and I could feel the t-case engage and light illuminated. How often is your light flashing? Is it a quick flash on and off? The t-case takes several seconds to change states so if you have a quick blinky flash I would take a good har look at that feedback wiring. I think you may have a short in there. If you can actually feel the t-case switching in and out of 4x4 than I would look at selector switch wiring and the switch itself. Note that my t-case would not engage/disengage unless the truck was running.
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Freshman User
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aaarrrrggghhh
What I have done so far: removed selector button-problem remains, disconnected plug at PVH solenoid-problem remains, I actually pulled the vac lines off of the hubs sealed them with golf tees and tape, and the 4x4 is still engaging and disengaging by itself?!?!?!?!?!? without any pulse from the PVH. HELP
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Senior User
Joined: Sep 2010
Posts: 201
Likes: 1
From: Ellensburg, Wa
Have you serviced the Auto/Lock hubs, they can get stuck engaged. This would have the running gear engaged but not the transfer case, so no power to the front wheels, thus eliminating any issue with vacuum system and explaining why you are still engaging with no vacuum to hubs. Service procedure here:
Welcome to guzzle's 4x4 Autolock Hub Lubrication Maintenance Web Page
You could try unplugging the transfer case gear motor encoder to keep truck from engaging 4X4 if you need truck until the electronics are sorted out.
Welcome to guzzle's 4x4 Autolock Hub Lubrication Maintenance Web Page
You could try unplugging the transfer case gear motor encoder to keep truck from engaging 4X4 if you need truck until the electronics are sorted out.
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Elder User
Joined: Jun 2007
Posts: 705
Likes: 1
From: Sandia Park, NM
What I have done so far: removed selector button-problem remains, disconnected plug at PVH solenoid-problem remains, I actually pulled the vac lines off of the hubs sealed them with golf tees and tape, and the 4x4 is still engaging and disengaging by itself?!?!?!?!?!? without any pulse from the PVH. HELP
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