Some more suggestions:
Visit this Link and Download a GM OEM Shop Manual
(courtesy @Mooseman) :
********* Please note that the FireFox browser has issues with the password handling and that these downloads are not under HTTPS, flagging them as security risks. Chrome and Edge work fine once you allow the download. ********* ATSG 4L60E Manual 4L60E Rebuild Manual 2005 GMC Envoy XUV...
gmtnation.com
(1) Using a DMM or a DVOM...
Test the Static Battery Voltage and note the measurement in your next Post. The Modern GM PCM-ECM Powering demands can be VERY Touchy and having a Reliable Battery as Fully Charged as possible is a good place to start...
Sorry for not mentioning this first.
(2)
"...all the wires for the fuel pump have been cut previously so I had to rewire it.."
There is No Doubt About It... Your Next Best Move is to get a Lighted
"Scope on a Rope" and Check the Wiring FROM THE FUSE BOX in the Power Distribution Center leading TO the FUEL PUMP for Continuity... Both in KEY OFF... KEY ON and doing so while performing Before and After checks on ALL Fuses involved to see if any Fuses Burn Out when the Key On "Start/Run" occurs, short of actually starting the Engine. Obviously, any wiring involved that gets
"HOT in RUN" vs. "
HOT AT ALL TIMES" should be identified and checked for any Shorts to Ground.
If your chosen method of Wire Repair involved the Technique of using "Twisted Wires, Acorn Insulator Nuts and Electrician's Tape..." The involved Cut or Damaged Wires should be pre-sleeved with Auto Quality Heat Shrink Tubes and then directly Soldered together and heat Shrink Sealed. This procedure should NOT be done if there are Gasoline Fumes or Fuel Leaks in the immediate vicinity to avoid Fire or an Explosive Ignition and Flame from this technique.
(3) Review Post #5 for
@Mooseman 's suggestion about clicking on the link to the
Security Re-Learn Thread and see if the vehicle Starts after you follow those directions to the letter.
(4) You are not there yet... but you should be able to use a Used PCM to get the SUV to Start and Run if the one in there now is FUBAR. IIANM...
perhaps the same idea with the BCM ...which MAY still need to be programmed via a Tech 2 and SPS to ensure that the Vehicle VIN and Security set up matches the one in the OEM installed BCM.
NOTE:
I Do NOT think that THIS is where the present problem lies... but to Answer your Question about the
Lift Gate Module and to help you to understand more about it ...please read on.
(5) The Question of
"Testing" an LGM (Lift Gate Module) is simply a Binary Problem:
a. Does the Vehicle Start-Run with the LGM CONNECTED to the Class 2 Network?
b. Does the Vehicle Start-Run with the LGM DIS-CONNECTED from the Class 2 Network?
With the GM Class 2 Databus Design operating between 0-7 Volts DC operating on a Single Wire, it means that ALL of the Modules share ONE SINGLE COMMUNICATION Strand. This design is arranged to allow ALL of the Modules on the Network to meet up at only Two Common Communication Junction "Combs"
. These are called "Splice Packs" in the GM Service Manual.
One Comb is under the Driver's Side dashboard and the
Other Comb is under the Carpet Flap beneath the Passenger Side rear Seat. ANY Single Malfunctioning Module is capable of Disabling the Entire Class 2 Network if either Shorted to Ground... or Shorted to Power at 12 Volts DC.
In this way , the LGM CAN be Taken Off Line as a functioning, connected Module WITHOUT having to tear apart the Rear Lift Gate to yank out the Three Connectors to do so.
Please note that with the LGM Dis-Connected, the Remote Key Fob Entry will NOT Function... but trying this out MAY allow you to use the Ignition Key to Start the SUV and go on from there.
(6) Use a Higher End OBD2 Scanner capable of recognizing and reporting UXXXX Codes (Class 2 Network Communications Error Codes) for any Communications problems.
(7) Next, you can locate these two GM Databus Ribbed Steel Network Junction "Combs":
a. Under the Left Side of the Driver's Side Dashboard.
b. Under a Carpet Flap beneath the Passenger Side Rear Seat. (The
LGM is on THIS One).
To help you see this entire Diagnostic Process at play with the correct tools to do so... Please Watch (Entirely) this long... but excellent Video from Robinson Auto showing how this process works: