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Strange 4/Low No-Shift Problem

This is a discussion on Strange 4/Low No-Shift Problem within the Mechanic's Corner forums, part of the TMC TECHNICAL category!
Originally Posted by rfdean Good news and bad news... I have confirmed that the reason the transfer case was not ...

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Old 08-20-2016, 09:02 AM
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Originally Posted by rfdean View Post
Good news and bad news... I have confirmed that the reason the transfer case was not shifting into 4low was because the N on the PRND123 would not light. After shaking wires and establishing some kind of connection, N lit up, so I managed to solve my original problem and the problem which is the subject of this post. I shifted into neutral, pressed 4low button, the lights flashed, I felt and heard a slight yet distinctive clunk sound. I pressed on the gas and could feel a distinctive difference in the way the truck felt after a foot or so (a little tighter?) so I thought I was good to go, and that it was in 4 low, but after about 4 or 5 feet, I heard a very loud clunking/grinding like the gears were bouncing around and not fully engaged. I immediately put it back into neutral, it made the grind/clunking noise again for a second but stopped when i got out of drive, and I was fortunately able to switch it back to 2 hi, and the truck drives...

I don't have any experience with 4wd except for what I had just done last night, so I may just be tripping on some normal 4wd noise, but I'm not convinced because it sounds really bad. From what I can tell, it may be the front differential, a wheel bearing?, or something in the transfer case. Not really sure where to go from here except for replacing fluid in the front differential. I already replaced the fluid in the transfer case a few months back with the blue stuff...
Well if it drives fine in 4WH with no noise then it more than likely is the Tcase. So that is where I would start. Changing the fluid in the front diff is easy, pull the fill plug, to make sure you can get it out, then the drain. Put drain plug back in and fill until fluid drips out of fill plug. Make sure you are sitting on a level surface.
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Old 08-20-2016, 07:57 PM
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Have you checked it for any transmission codes?
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Old 08-23-2016, 11:48 AM
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shaking wires

Did you determine the actual location of your bad connection or just left it alone after it started working?
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Old 08-25-2016, 11:23 PM
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I never determined the location of the loose connection. I just left it alone... After reviewing the manual, I think 4 hi is all i will ever really need. I plan to check for codes whenever I change the differential fluid, but at this point I'm not complaining. Thanks for the help.
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