3Js

Up till now the trans has been shifting normally. 2006 Burb LS, 2wh drive, 5.3, Auto trans (4L60E? ). Approx. 178K miles
This started yesterday.
The transmission won't shift out of first gear unless I let off the accelerator. So far it will shift and drive normally after the initial shift. If it downshifts I need to repeat the let off pedal.

Fluid is a tad overfull but has been like that since purchased in 2020. I have not yet scanned it. No CEL light.

I've read a few things. Some say VSS, TPS, trans solenoids and some say rebuild.

Any experiences?

mountainmanjoe

I wouldn't expect much more than that out of a 4L60e. Especially if you don't know the full service history.
Did you ever do a tranny fluid+filter change on it?

3Js

The fluid looked decent so it hasn't been changed. I'll check with our master tech Monday to see if he's run across this before.
I'll drive it or have it towed by AAA and have it scanned and/or diagnosed. I'll go from there.

3Js

So, more info. It drives fine once in gear but it seems I need to lift for each shift. Get the tach to 2500-3000, let up, feel it shift, resume driving.

Some research says replace the TPS. Still no CEL light and no code present. I will try to get the guy at the shop to check the signal from the TPS and see what that says.

VSS seems to be a NO because the speedo is still operating normally.

3Js

No input??....Oh well. I guess in reponse to no info I won't post the resolution.

mountainmanjoe

I already gave you input. You killed it by not changing the fluid.
And I already know the resolution ... it's a new transmission or vehicle.

Rednucleus

I was patiently waiting for your report from your tech!!

3Js

Well, Scanned for codes with the big shop scanner. No transmission codes.
Only codes stored were P0172 and P0175. These are more than likely from the CAI. Over the years they have popped up prior to this situation a handful of times in colder weather and harder acceleration/deceleration
Still no CEL light.
Checked fuses. All good.
Checked Iginition and PCM voltage. Good at 14.7V. running.
ECU/ECM/PCM was replaced this year. VIN programmed with most recent updates. Replacement was a bad diagnosis from a different place for an A/C issue. A/C issue was in the high side wiring and pigtail. I still have the OE ECU and a lifetime warranty on the replacement it it turns out to be this.
Cleared all stored codes, test drove. Still has problem.drives normal once I get it to shift into each gear, 1-4

I will try to suck out the overfill this weekend. It's only about 1/2 a quart. Fluid isn't burnt and is still quite pink. Slight smell. I'm also going to go ahead and replace the TPS even though there is no code. Dang TPS is riveted on so I need to drill the rivets and install new hardware when changing TPS.

3Js

just an update after 6-7 months.

I didn't think it was the problem but, my wife said to try anyway. Replaced the TPS. No change. No codes. No check engine light.
I've gotten quite good at the manual automatic. First to second shift is pretty smooth. The other shifts are easier. Drives normal otherwise.

I will try and talk to a transmission guy I know if I can ever make it over on a weekday. Either that or I continue to drive till it dies....