Would unknown driver light on cause envoy not to shift in to second gear

There could be several issues that could cause your GMC Envoy's transmission to not shift gears properly and the RPMs to rev high. Here are a few potential problems that you may want to consider:

1. Low transmission fluid: If the transmission fluid is low, it could cause problems with the shifting mechanism. You'll want to check the transmission fluid level and add more if needed.
2. Faulty shift solenoid: The shift solenoid is responsible for directing transmission fluid to the appropriate gear. If the solenoid is faulty, it could cause shifting problems.
3. Worn transmission bands or gears: If the transmission bands or gears are worn, it could cause the transmission to not shift properly and the RPMs to rev high.
4. Clogged transmission filter: A clogged transmission filter can restrict the flow of transmission fluid, causing shifting issues.
5. Faulty transmission control module (TCM): The TCM is responsible for controlling the transmission. If it's not functioning properly, it could cause shifting problems.

I would recommend having a mechanic diagnose and fix the problem for you. It's important to address transmission issues promptly, as they can lead to further damage if left unchecked.

https://www.cargurus.com/Cars/Discussion-t5264_ds50616

Hi, I exactly I have a gmc 2002 envoy and I have exactly this problem and we just change the oil and all transmission sensor and is still doing it so what problem can be thank you

There is a linkage hooked to the indicator that may be broken

Lots of possibilities, but based on the information you've given, the most likely scenario is that the battery voltage has dropped too low to engage the starter. It may still be strong enough to turn on dash lights, interior lights or even headlights, but those draw far less power than the starter. That is assuming it is not 'turning over' based on you saying it will not start. If it turns over (cranks the engine) normally, but still will not start, then that is different. The gear shift on most vehicles will move if you have the key turned to the on position, but I cannot be positive about a 2004 Envoy, so that part seems a bit odd. The steering wheel should be unlocked when the key is in the on position, so that part is normal. If it is a battery problem, that could have been caused by some other issue (failed alternator, for example), or could have been as simple as lights being left on. I hope that helps.

have code retrieve it is normal for transmission won't shift if there is no speed to pcm
ABS light on there is no speed for him too and brake light
look for wire at transmission for speed sensor or why no speed sensor not working

either the transmission bands need to be adjusted or the solenoid is bad and needs to be replaced. The first thing would be to change tranny fluid and filter.

sounds like you have a broken shifter cable.Go under the rig and shift the transmision manually.Put on the parking brake and on the drivers side of the trany should be the lever to move.Look for the broken part while you are there it will also help to locate the shift lever on the trany.

Try putting your transmission in neutral and slowly shifting the 4wd selector to each position but you have to wait a few seconds between selsctions as it has to go through your vehicles computer, shifting to fast will cause your symptoms. I hope this helped you out. Roger

This sounds like your alternator maybe going bad. When your alternator starts to go bad lights such as headlights, radio lights will go dim wipers will start to move slower but if you cut one of the things off such as the wipers the lights will get brighter for a few minutes then not long the car will shut completely down. Hope this helps.