Keyless entry doesn’t work and the rear hatch will not open. What fuse controls these?
Since your Envoy is getting older…I suggest you buy a Haynes Repair Manual for your year Envoy. You will need it in the future. I found this info for resetting your remote entry system:
Turn ignition switch to OFF position.
Remove RADIO fuse 17 from fuse block.
Cycle ignition switch from OFF to RUN three times within five seconds until the door locks and the hatch release cycle, indicating the Body Control Module is in the Programming
Press and hold BOTH LOCK and UNLOCK buttons on remote control door lock transmitter for 16 seconds.
Door locks will cycle once, confirming the transmitter code is programmed. The door locks must cycle completely to unlock before proceeding.
Any transmitter code that was previously programmed has been erased.
Body Control Module is now programmed to remote control door lock transmitter.
When programming the Body Control Module to match remote control door lock transmitters, the first transmitter code matched will be stored in memory unless a second remote control door lock transmitter is matched at the same time. If programming the Body Control Module to match a second transmitter, repeat step 4. This must be done before the RADIO fuse 17 is reinstalled.
Ignition switch to OFF.
Reinstall RADIO fuse 17 to fuse block.
Are you sure the battery in the key fob is not spent? The Autozone near my house has a neat little test station that can tell you if the key fob is sending a signal, either RF or IR. It is plastered with ‘Energizer’ labels, because they sell those batteries for the fobs. Try that first before tearing into the wiring.
Another way to test any remote is to use an AM radio set to the lowest channel white noise. If the remote works then it will cause the radio to buzz. Point directly at the speaker. I’ve used this method for 25 years.