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Transmission Mods for Reliability and 4WD Fix and AFM Removal Question

Eneerge
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Eneerge Enthusiast

Eneerge

Posted
Posted

Evening. I've had the pleasure of driving a 2015 Silverado 1500 High Country 6.2L (8-speed) since 2016. Along with that, I've had the whole transmission replaced once, torque converter thrice, and a few transfer case issues (...and door locks have stopped working twice and repaired for $700 a pop, roof leaking near the SiriusXM antenna, couple dead batteries, and the never ending shudder). I have ~72,000 miles on it.

 

Anyways, now my truck is stuck in 4-wheel drive, which makes me think there's an issue with the transfer case (again) or the Transfer Case Control Module. I'm taking it to the dealer again next week. In the meantime:

  1. is there anyway to get the truck out of 4wd?
    I have tried pulling the 4wd TREK fuse in the fuse box and also leaving the battery unplugged for ~6 hours to see if it would reset the TCCM, but that did not do anything.
  2. I'm driving as little as possible, but would running it in this 4wd (high) for an extended period potentially cause other issues?

 

Additionally, I've been reading up about the new transmission by pass valve which is supposed to reduce the temperature of the transmission fluid and make the transmission last longer and produce a smoother shift. I'm considering flipping the pill or buying a Sure Cool, because I have transmission issues at least once a year. But I had a few questions:

  1. Has anyone run a flipped pill for several years without issue? I'm a little skeptical of the longevity of that fix.
  2. The Sure Cool system (https://superiortransmission.com/product/superior-stl010/ says it "fits all 2015 up 6L80/90E and now fits 8L80/90E 2016-up". Well, my truck is a 2015 with an 8-speed. Would this Sure Cool system work in my truck?
  3. Why isn't there a bulletin for the 8-speed? I was under the impression the 8-speeds were the ones having the most problems.

 

And finally, I talked to a shop that recommends that I get the AFM removed and that that may also increase the reliability. Apparently AFM puts more stress on the torque converter and could cause engine issues?

  1. Would anyone recommend against doing the AFM removal?

 

Gagliano7 Enthusiast

Gagliano7

Posted
Posted

I tuned out the AFM with 40 miles on the truck. Before i did it coming to a stop it would shutter slightly. Since i have had it turned off the trans is perfect. I now have 25000 miles on my 2018 Sierra 6.2 8 speed.

sk Senior Enthusiast

sk

Posted
Posted

There is a TSB for trucks getting stuck in 4WD.  Unfortunately I don't know the number off the top of my head but it is posted somewhere in these forums.  Running in 4-HIGH can DEFINITELY cause problems since the front differential never disengages (but if you happen to be stuck in AUTO you will be fine).

 

I replaced the trans thermostat (mine is a 2015 5.3/6-speed).  Found the part online for $38 and it took me all of 15 minutes to do.  Well worth it -- my temps while pulling a loaded landscape trailer on the hottest days are running about 40 degrees cooler.

 

I haven't done anything to AFM so I can't help there ...

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