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View Full Version : another LB7 locked ECM


jeeper
May 30th, 2022, 09:07 AM
Hello. I recently (within the last 2 months) bought a 2004 Silverado LB7 that needed new injectors. I have since replaced the injectors and the truck runs ok now. My problem is I now have a security light on in the dash and the serial number is corrupted. Not only that, I cannot read the ECU with EFILive to even flash the computer. I'm not sure the security light was on when I bought the truck but I'm sure it is now. The truck sat for almost two years before I got it and I know it sat for at least two weeks with no batteries connected.

I have tried using my V2 to cal flash the ECU but it says the computer is locked with a custom key. It tried over 3200 something keys and it took several hours.

Also it seems to lose it's prime when it sits overnight. I seem to have to prime the fuel before I start it or it cranks a long time before it will start. But if I prime it it will start quickly and after it runs a few minutes it will fire off immediately when I try to start it after short period shut downs.

My main concern is the security light. I need to get that sorted first.

Any suggestions?
killerbee
May 31st, 2022, 02:24 AM
My main concern is the security light. I need to get that sorted first.

Any suggestions?

I have about a dozen or so LB7 ecms with the same problem. I usually have to replace the ecm for the customer. The first gen has an unknown spontaneous loss of identity issue, and I am not clear what the main cause is. I happy to put it on the bench if you want to ship it off.
In-Tech
May 31st, 2022, 05:57 AM
I'm not too familiar with the diesel stuff. Yeah, for some reason these LB7's fubar the parameters section which corrupts the seed/key, serial # and vin too, basically the entire "block". I can repair them on the bench with my BDM. I'm not sure about the security light. Do you guys have to do a VATS relearn for that when replacing the ecm?

See also https://service.efilive.com/kb/articles/nvram-status-gm-gas-diesel
jeeper
May 31st, 2022, 01:17 PM
See also https://service.efilive.com/kb/articles/nvram-status-gm-gas-diesel

Thanks. I was afraid of that. I'll call Wait4ME Performance tomorrow to see what they can tell me.

I appreciate the help. And thanks killerbee for the offer to put it on the bench. I'll probably try Wait4Me because they are much closer to home for me.

I will update this thread as I learn more.