It has 94,000 miles on it, dropped the pan about 88,000 miles and changed the filter and Fluid and didn't see anything of concern. Shifting it to manual seems to get it into gear then it shifts fine. It doesn't do it every time but a few times in the last couple days. No check engine light either. Any suggestions on where to start?
17 tahoe transmission popping out of gear at stop light
- Thread starter tim crow
- Start date
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What transmission and what gear(s) are neutralizing?
What gears are neutralizing?
See post 4.
Scan the pcm for codes, sometimes the CEL won't illuminate for non-emissions related problems. Falling out of gear is what we refer to as "neutralizing" or "a false neutral condition". It happens when either there's a loss of line pressure in one or more clutch apply hydraulic ciruits inside the transmission or when one or more applied elements (clutch packs) are burnt and no longer able to hold when compressed.
If your problem is due to a loss of line pressure then id test the TEHCM (clutch pressure control solenoids, pressure switches) corresponding to the gears that you're losing for function.
If presssures are good but your neutralizing trans is likely in need of overhaul.
1st gear only
Ok - trans likely has to come out...sounds like rear sprag is beginning to roll over. You may or may not have a gear ratio error code but neutral in first is usually sprag or cracking 1-2-3-4 piston.
ETA: Can also be #1 check ball getting stuck in the spacer plate. Check the valve body for this first. If that CB is not worn, sticking in the plate or migrating then the problem is in the case.
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Would something mechanical like that be an intermittent issue? Thanks for your help.
Yep. That is usually how it starts, regardless of what's failing. The sprag usually fails more quickly than the other parts mentioned.
Not sure if you saw my edits above so will put here also but put a bi directional scan tool on it to see if its electronic/electrical - if no electronic faults are noted then drop the valve body, split the halves and look at the check balls for wear. If worn then replace the spacer plate and install a Sonnax zip kit. Then once everything is back together, do a fast adapt relearn before test driving.
You still may have the condition if there are multiple areas with problems; in that case yank and overhaul the transmission; replace the TC with an upgraded one...see my sig for the "6L80 Info Thread" - it has all the pertinent details.
