2003 LB7 Duramax failure to return to stock program - guidance please

Hi all

I have a 2003 Duramax LB7, original owner so I know the ECM hasn't been touched by any previous programmers and I can't recall the dealer ever having touched it either. About 3 months ago I started working with a diesel performance shop in the pacific NW, they read out and saved my stock tune, saved the .ctz file and emailed me a copy as well. Then they installed a DSP5 tune set from a well known tuner with Flashscan V2 version 8.02.21. Fast forward to today, we are debugging a driveability issue and wanted to flash the ECM back to stock to create a baseline. Today they tried to flash my ECM back to the stock tune that was previously read out, and the truck would crank w/o starting, security light on the dash. Sure enough when we put it on the bench and read with Efilive, the VIN number was incorrect. It wasn't all zeros like the 01/02 ECMs seemed to be prone to doing, but something like mostly zero with only the last 6 digits containing a number.

We're at a loss, he assumed the original tune he had saved was possibly corrupted somehow and suggested programming a clean stock 03 image back into the unit. What is the recommended course of action to proceed to get this ECM back to stock with the correct VIN?

I took a look at the .ctz file and the text headers did contain valid S/N and correct VIN. (I removed some of the actual digits with xxxx) Is there any way to verify validity of a .ctz file and confirm the theory that the stock tune read out of the ECM 3 months ago was somehow corrupted?

Binary=UPLOAD
Software=V8.02.21.404
Bootblock=V2.07.08
BootblockDate=20180704
Firmware=V2.07.138
FirmwareDate=20181025
BootLoader=DLB7_v1.3R
ObjVer=08.04.73
ObjDate=20180515
...

[VEHICLE],19
Stream=E54
StreamID=4
VIN=1GCJK39103E33xxxx
SN=3128CT08xxxx
OS=15189044
BB=0
CVN=$0
CodeVer=0
CodePart=
BootVer=0
BootPart=
PartNumber=0
Code=
ProductID=
Name=
COSOnly=0
SDMKey=0
ManufactId=
Custom=0
[SEGMENTS],11
S00=15189044
S01=15189052
S02=15076379
S03=15076354
S04=15076385
S05=15076392
S06=00000000
S07=00000000
S08=00000000
S09=00000000
S10=11463752
[SECURITY],21
Read=1
Modify=1
AutoLock=0
Serial=0
License=0
Remote=0
Master=0
SN=0
Password=0
Checksum=1
CalFlashOnly=0
FullFlashOnly=0
OverrideOS=0
RemoteKey=
RemoteKeyFrom=
RemoteKeyTo=
TryAltKeys=0
AssumeLockFaulty=0
LowSpeed=0
CMFastCan=0
VIN=0
[INFO],4
CalibratedBy=.
ModifiedBy=.
Created=20190219
Modified=20190219
...binary stuff follows

Unfortunately the LB7 ECM has a habit of locking / corrupting part of itself that causes this issue.
One day it is fine, next day this happens without anyone doing anything abnormal to it. There is nothing you can do to recover it, I can put you in touch with someone that can restore it back to how it was (where are you located?)

Quote:

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Originally Posted by GMPX

Unfortunately the LB7 ECM has a habit of locking / corrupting part of itself that causes this issue.
One day it is fine, next day this happens without anyone doing anything abnormal to it. There is nothing you can do to recover it, I can put you in touch with someone that can restore it back to how it was (where are you located?)

---

Thanks for the insight, that will keep us from wasting more time. I'm located in Oregon. Anyone in the Portland, OR area you would recommend? I have heard Guy at SoCal Diesel can recover these but prefer local if possible.

Also, should we use the stock .ctz file that was read out of the original ECM, or is it safer to start with a known clean stock tune for an 03? (OS build 9044)

Thanks again.

Welcome from Seattle!

SoCal is probably your "local" option here, I believe Jesse at Wait4Me can do them as well but he's in Indiana.

For your base tune, it probably isnt the stock tune that caused the corruption BUT since you have to go through the hassle of sending the ECM out, it may be better to start with a known good base from the DropBox or your tuners' stash.

Quote:

---

Originally Posted by ScarabEpic22

Welcome from Seattle!

SoCal is probably your "local" option here, I believe Jesse at Wait4Me can do them as well but he's in Indiana.

For your base tune, it probably isnt the stock tune that caused the corruption BUT since you have to go through the hassle of sending the ECM out, it may be better to start with a known good base from the DropBox or your tuners' stash.

---

Hi Erik!

Thanks for the pointer. I boxed up the ECU and sent it off to SoCal Diesel today. They were also super helpful answering a few of my questions on the phone today too. :good:

Wanted to follow up on the resolution of this, in case it helps others in a similar situation trying to keep their old LB7 rolling down the road. I sent the ECM off to SoCal Diesel, they put it on the bench, everything seemed to be OK because serial & VIN numbers looked correct with their setup. So after discussion we mutually agreed the best approach would be to just try a full flash of a clean 2003 stock LB7 OS on it (9044) and also do a VATS disable. When I got the ECM and installed it, the truck started and ran fine but the security light stayed on persistently. The well documented 30 min ECM - BCM security learn procedure would not work because the security light would not go out after 10 min. According to the GM manual, the BCM controls the security light in the instrument cluster, so some security related communication protocol between the BCM and the ECM was not working correctly. So I pulled it and sent back to the good Dr. SoCal for their surgery which replaces certain internal components. Just got that unit back with the stock LB7 OS on it (+VATS disable) and installed today. Truck starts, runs fine, and - NO SECURITY LIGHT on the dash. Everything seems perfect. Thanks tons to the guys at SoCal for their expertise, they saved me a bunch of $$$. Highly recommended.

Glad you got it sorted out and thanks for reporting back on the fix!

is the pins on the lb7 and ls1b controller the same for the bench harness? according to everything i have found it is but i cannot get a read on the lb7 computer but tried a spare ls1 computer and found that i could get it right away