Motor refresh complete, now no crank, no start

[SubSonic]

Good luck with this. I’m really curious as to what the problem is.

Been following along, hope the new BCM does the trick--looking forward to the update. Good luck!

 

[Doubeleive]

sounds a little to wierd to me, I wonder what the life expectancy of the bcm is then and how many people would end up completely stranded if there battery dies, just doesn't seem right to me. I am going to ask my local dealer and see if they have ever heard of that before and what the catch is, seems like there would be a lot of dead bcm's in the junk yard I'm sure plenty have been left with the key on and no battery, same thing if you left your keys on accidently and drained the battery

 

[hagar]

Onstar can read your codes and unlock your doors and stuff, not the weirdest thought that they designed a way to keep communication open during an emergency. Anywho... Just telling you what the dealer told my buddy happened with the exact same problem, guessed that you turned the truck on the move it around while apart the same he did. I dont even know if its a fact, just what the dealers said and knew the fix in minutes. They might have just made it up, who knows. Good luck

 

[hagar]

The only fact i know is they changed the bcm and the problem went away. The rest might have been fiction. It for sure wasnt the ecm they changed, so hopefully yours is a different problem with the same exact symptoms.

 

[Doubeleive]

EDIT: onstar does have a backup battery (on some vehicles) however, there is no battery inside the bcm of any kind, the next most likely scenario if the problem is the bcm then it was somehow damaged by a electrical surge or something of that nature when either disconnecting or reconnecting the battery or other plugs/harness after the battery was hooked back up or something along those lines.
the gm upfitter guide specifies all of the functions of the bcm one of them being yes it will retain RAP beyond the 10 minute timer (or indefinitely) if there is a open onstar call until the call is ended. now this means it runs off of the main battery (or backup battery) if you look at a opened bcm it is a fairly simple board with lots of I/O's and a couple relays and a little "clicker type speaker" or something but no battery.....

so far my conclusion as far as the bcm is concerned is if the radio works, sunroof works, power windows work, door locks work then it may not be the BCM that is causing the problem (just a theory) because all of those things are specific to the bcm. the airbags are also controlled by the bcm so if the airbag light is turning off properly and not giving you a service airbag error this would also lead me to believe the bcm is not the problem. (but again just a theory).

now I haven't personally ran into a issue with the nnbs and the gm security system, but on the nbs if the security system was a problem the engine would start and die within a second and the security light would flash until you did the 10.35 minute relearn procedure, but I seem to recall when I bought my spare key and tried to just start it without doing the key learn first it didn't even try to start.
do you think it's possible the security lockout is causing your problem? is the security light lit up or blinking or anything when you try to start?

 

[Doubeleive]

just for reference in case this is the problem (30 min relearn)
GM Vehicle Theft Deterrent (VTD) Relearn Procedures
To perform a relearn for Passkey III system, make sure there is a fully charged battery in the vehicle. The battery will be used for 30 minutes without the alternator available for charging. Connect a battery charger to the battery to ensure power is available while programming. When performing this relearn, all previously learned keys will be erased. Additional keys may be relearned immediately after the first key has been learned by inserting the additional key and turning the ignition switch to on within 10 seconds of removing the previously learned key.

1. Insert a master key (black head) into the ignition switch.
2. Turn key to the “ON” position without starting the engine. Security light should turn on and stay on.
3. Wait for 10 minutes or until the security light turns off.
4. Turn key to the “OFF” position for 5 seconds.
5. Turn key to the “ON” position without starting the engine. Security light should turn on and stay on.
6. Wait for 10 minutes or until the security light turns off.
7. Turn key to the “OFF” position for 5 seconds.
8. Turn key to the “ON” position without starting the engine. Security light should turn on and stay on.
9. Wait for 10 minutes or until the security light turns off.
10. Turn key to the “OFF” position. The key transponder information will be learned on the next start cycle.
11. Start the vehicle. If the vehicle starts and runs normally, the relearn is complete. If additional keys need to be relearned:
12. Turn the key to the “OFF” position.
13. Insert the next key to be learned. Turn the key to the “ON” position within 10 seconds of removing the previously used key.
14. Wait for security light to turn off. It should happen fairly quickly. You may not notice the lamp, as the transponder value will be learned immediately
15. Repeat steps 12 through 14 for any additional keys.

 

[hagar]

I just googled "onstar battery dead" and it came up with all kinds of info about backup power sources installed in onstar vehicles to keep the system alive during an emergency where power is lost.
I am simply stating the info that the gm dealership told buddy, but if you are arguing that the onstar system doesnt have a back up power source it appears you are wrong

 

[hagar]

Gm even lists one of the features of the onstar button is to send help for a dead vehicle battery.

 

[Doubeleive]

Gm even lists one of the features of the onstar button is to send help for a dead vehicle battery.

ok, I did a little looking and apparently the onstar does have a backup battery (on some vehicles), however this battery is not contained in the bcm. it is either under the passenger seat or attached to the side of the onstar module, I looked under my seat and there isn't one there just the backup sensor module. on these trucks the onstar module is under the radio behind the dash, not sure if they have a backup battery the part is not listed anywhere only the module, only onstar batterys I can find are for impala, saturn.
even gm parts direct which does list a backup battery for the impala does not list one for any of the 07-14 Tahoe, Yukon, suburban, escalade

 

[RST Dana]

just for reference in case this is the problem (30 min relearn)
GM Vehicle Theft Deterrent (VTD) Relearn Procedures
To perform a relearn for Passkey III system, make sure there is a fully charged battery in the vehicle. The battery will be used for 30 minutes without the alternator available for charging. Connect a battery charger to the battery to ensure power is available while programming. When performing this relearn, all previously learned keys will be erased. Additional keys may be relearned immediately after the first key has been learned by inserting the additional key and turning the ignition switch to on within 10 seconds of removing the previously learned key.

1. Insert a master key (black head) into the ignition switch.
2. Turn key to the “ON” position without starting the engine. Security light should turn on and stay on.
3. Wait for 10 minutes or until the security light turns off.
4. Turn key to the “OFF” position for 5 seconds.
5. Turn key to the “ON” position without starting the engine. Security light should turn on and stay on.
6. Wait for 10 minutes or until the security light turns off.
7. Turn key to the “OFF” position for 5 seconds.
8. Turn key to the “ON” position without starting the engine. Security light should turn on and stay on.
9. Wait for 10 minutes or until the security light turns off.
10. Turn key to the “OFF” position. The key transponder information will be learned on the next start cycle.
11. Start the vehicle. If the vehicle starts and runs normally, the relearn is complete. If additional keys need to be relearned:
12. Turn the key to the “OFF” position.
13. Insert the next key to be learned. Turn the key to the “ON” position within 10 seconds of removing the previously used key.
14. Wait for security light to turn off. It should happen fairly quickly. You may not notice the lamp, as the transponder value will be learned immediately
15. Repeat steps 12 through 14 for any additional keys.

And if you have push start?