ABS Sensor / Sluggish Transmission C0900 & C0899

[UDKingo]

Hey everyone, did some searching but couldn't find exactly my issue.

First, my 2010 Tahoe Flex RWD (185k) is overall running well. However, during a recent 500 mile road trip, shifting gears was mostly okay but seemed a bit sluggish at times almost like revs and gears aren't matching. Fluid is red and at the right level and I just don't think its a physical transmission issue.

I do not have a CEL light, but when I run a full system scan, I get 2 "Anti-Lock Brake system codes":

-C0900: Device #1 voltage high
-C0899: Device #1 voltage low

I figured this was unrelated, but then I found this video:

and this site that says this sensor could cause transmission issues. https://autocareaids.com/can-abs-sensor-cause-transmission-issues/

Therefore, before I get ABS sensors and try that, are there any other sensors, relays, connections etc I should try first? Has anyone else had something like this?

Thanks!!

 

[davidavidd]

Oil isn't always the best indicator (unless you send it to a lab to find out what's floating around), your transmission may be at the death line and the oil still looks perfect: a stuck valve, a sprag about to break , a broken internal piston. Scan the transmission module and do basic tests on different gears to rule out other faults. Temporarily remove the fuses from the ABS system and drive the truck (in a safe place) to see if you notice any difference.

 

[UDKingo]

Oil isn't always the best indicator (unless you send it to a lab to find out what's floating around), your transmission may be at the death line and the oil still looks perfect: a stuck valve, a sprag about to break , a broken internal piston. Scan the transmission module and do basic tests on different gears to rule out other faults. Temporarily remove the fuses from the ABS system and drive the truck (in a safe place) to see if you notice any difference.

I did scan all modules and did not get anything specific to the tranny, but got the following as mentioned.
-C0900: Device #1 voltage high
-C0899: Device #1 voltage low

I have dropped the pan and changed the fluid twice in the last few years. Again, it's shifting mostly fine, just more of a lag sometimes.

At this point I am really just wanting to see if its worth swapping the ABS sensor or if that's a waste of time.