Thank you to everyone who has assisted me.
Vehicle Issue: I have a 2008 Trailblazer. The customer reports intermittent issues with the vehicle not cranking or starting, while sometimes it starts without problems. Additionally, the headlight's center lock does not function.
Actions Taken: I inspected the Body Control Module
(BCM) and found water damage inside. After replacing the BCM and programming the VIN, the lights and center lock started working. I also replaced the Engine Control Module (ECM) E40. However, I encountered issues while attempting to disable the immobilizer using HP Tuner. Despite multiple attempts to read the module and disable the immobilizer, the process was interrupted halfway with a "Timed Out" error. I'm trying to to return the old ECM but same issue all fuse checked ,l want to return Old condition .
Can anyone provide guidance or assistance with this issue?

Hello.  Set the firmware reading speed to slow.

hi remove 2 fuses from fuse box 1 called brake light other 1 i forget fuse box location under rear seats when ever you program trailblazer ecm you have to remove that 2 fuses then program ecm after that fit the fuses again

Liftgate and abs 51 and 19 fuses

On 4/22/2024 at 7:56 AM, abualicrs said:

Thank you to everyone who has assisted me.
Vehicle Issue: I have a 2008 Trailblazer. The customer reports intermittent issues with the vehicle not cranking or starting, while sometimes it starts without problems. Additionally, the headlight's center lock does not function.
Actions Taken: I inspected the Body Control Module
(BCM) and found water damage inside. After replacing the BCM and programming the VIN, the lights and center lock started working. I also replaced the Engine Control Module (ECM) E40. However, I encountered issues while attempting to disable the immobilizer using HP Tuner. Despite multiple attempts to read the module and disable the immobilizer, the process was interrupted halfway with a "Timed Out" error. I'm trying to to return the old ECM but same issue all fuse checked ,l want to return Old condition .
Can anyone provide guidance or assistance with this issue?

Do it on bench ,

I Don’t have pinout for this module( p20 or E40)

11 hours ago, abualicrs said:

I Don’t have pinout for this module( p20 or E40)

https://www.customecm.com/tune-file-repo-and-info-here/bench-harness-pinouts#h.p_lZUp3QhysIUi