Replacing TCCM on 1999 Yukon looking for pointers

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Smooth_Rider

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Hey guys

I'm still pretty green here but I posted a while back about my shifting issue with my 99 Yuk and want to again thank all of you who responded. I was a wee bit overwhelmed as this is the first major problem I've had with my "first" all electronic transfer case 4wd (I also have a 99 F250 7.3, but has manual TC, manual locking hubs, and manual 6sp...much less to break IMO).

Anyways, I largely took everyone's advice, got a scanner, and think I have it narrowed down to the TCCM. I posted a detailed response in the original thread but that thread is a few weeks old and nobody has responded to my update (here: https://www.tahoeyukonforum.com/threads/update-99-yukon-np8-codes-1-2-shift-scan-tool.143970/ )

I bought a used TCCM off ebay for cheap, just in case I screw something up, or whatever (I suspect) caused the old one to fry repeats, I'm not out a lot of money and can restart from the beginning if necessary. I read that these do not need any programming- just disconnect battery, swap TCCMs, connect battery. My questions: is it that simple? Any other steps? I have the dash half torn apart just to be able to see the part with a flashlight. any tips on removal? From what I can tell the 99 and oddball 2000 OBS are the only years this TCCM was used up under the steering column before being moved behind the light switch on the GMT800. I haven't found much on it. See my other post (link above) on how I diagnosed/why I think it's TCCM.

I also wanted to note that a lot of these problems seem to correlate to ground issues and that my truck has been in the Phoenix AZ valley it's entire life and you rust-belt guys would probably piddle yourselves on just how corrosion free this thing is. Also my truck does NOT have the ground under the drivers door by the frame rail. All the grounds I see look great and so do the wiring harnesses under/on/near the TC and Trans.
 

res02p35

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See my post in this section if you have not figured it out. It's simple
 

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