TRANSMISSION

This might or might not be a transmission issue. The quickest and cheapest thing to check is the Transmission fluid If it is red and to the proper fill line it is fine if it is too low or discolored like brown or black you have a problem there. There are other things to check as you could have fuel feeding problems, spark problems, without seeing the car I wouldn't know.

it could just be a bad sensor on the outside of tranny,or the lockout in the tourk converter has gone bad,I would have sensors checked first.

My truck did the same thing. Did you ever figure out what it was that caused the problem?

Hi, did you ever find out the issue? I have an 06 Envoy that did the SAME thing to me tonight, I just bought this truck a month ago and I pray it is just the sensors. Please let me know ASAP, thanks

I replaced the whole transmission with a heavy duty rebuilt one from a transmission shop. The GM tranny was shot. Check your fluid color, if its black in color it is probably not a sensor. Good luck!

Oh that sucks....ok thanks. My fluid is still red tho so hopefully it is just the sensors. I guess I have to figure it out...

Replace the tranny. Gmc had a bad torque clutch slip solenoids amoung the other 3. The problem is the design of the lower portion of the tranny not enough flow... I have a 05 Envoy Xl.. I sold it this morning, but as i drove it to their house the transmission went completely out. Unfortunately i gave their money back. But thats me..Now i need to go buy a transmission, install it and resell it. Cuz i dont sell junk.. So if you have an issue with yours, take it apart and replace the seals,all 4 solenoids and replace pump..cheaper go get another transmission for $300