Transmission not working

Tiny
ALL4FAMILY
  • MEMBER
  • 2004 GMC ENVOY
  • 6 CYL
  • AUTOMATIC
  • 18,000,000 MILES
My transmission went out. I changed the gears to 4wd to get over the snow without putting it in park first. It was in drive and my foot was on the brake 5 days ago. Is that why it's out now?
Monday, February 22nd, 2021 AT 6:28 AM

1 Reply

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,885 POSTS
Hi,

That shouldn't have hurt anything. You should be able to shift "on the fly" meaning while moving.

Also, based on how it happened, it sounds more related to the transfer case and not the transmission. Are you able to select a different option on the 4wd system? For example, when stopped, place the shifter in neutral and select 4lo. Does it shift?

Next, if it doesn't work, we need to scan the can bus on the vehicle. CAN stands for controller area network. All the modules/computers are tied together via a couple of wires. This type of scan would identify any problems with one of the modules.

Here is a video that shows how it is done:

https://youtu.be/InIlnsjOVFA

Try shifting the way I suggested and see if anything happens. Also, when doing it, listen closely to see if you can hear the actuator moving on the transfer case. It is an electric motor that makes it shift. You should hear something.

Let me know what you find or if you have other questions.

Take care and God Bless,

Joe
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Monday, February 22nd, 2021 AT 5:23 PM

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