is this possible? copy and save oem cals

American Delco GM ECUs and PCMs, ALDL, OBD 1.5.
Posts: 16
Joined: Thu Feb 19, 2015 12:54 am

Re: is this possible? copy and save oem cals

Postby dmaxben » Tue Feb 16, 2021 12:41 am

Gatecrasher wrote:It came out of a wrecked 16 Corvette. PN 13510531. Looks like they only ever issued one OS for this thing. 13511493. It's about as crude as you can get for this test, so maybe that's working in my favor? I've got just the BCM on my desk, hooked to an MDI. I'm copying and pasting commands one by one with the DrewTech J2534 software. I set a periodic tester present message at a rate of 4.5 seconds, and sent a mode $28 to disable normal communication, mainly to keep the logging noise down. I could have set a filter instead. Everything else was done in the scratchpad field on the DrewTech software.

Just for fun, I cut power to it since I don't have a way to gracefully shut it down yet. MEC was still at 0x10 after a restart. I guess it didn't decrement to 0x0F because it wasn't a proper ignition cycle. I definitely didn't return to 0 though. The write stuck.

Are you doing this over high speed or low speed CAN? Mine was done on high speed. The BCM will respond to some things on low speed, but doesn't seem to like doing diagnostics on that bus.

Code: Select all
14:28.412109,CAN,0x00000001,00 00 02 41 01 3E
14:28.423638,CAN,0x00000000,00 00 06 41 01 7E A0 00 00 00 00 00
14:32.605241,CAN,0x00000001,00 00 02 41 02 1A A0 00 00 00 00 00      //Check MEC
14:32.613478,CAN,0x00000000,00 00 06 41 03 5A A0 00 00 00 00 00      //MEC at 0
14:32.912563,CAN,0x00000001,00 00 02 41 01 3E
14:32.923454,CAN,0x00000000,00 00 06 41 01 7E A0 00 00 00 00 00
14:37.412543,CAN,0x00000001,00 00 02 41 01 3E
14:37.423278,CAN,0x00000000,00 00 06 41 01 7E A0 00 00 00 00 00
14:41.912521,CAN,0x00000001,00 00 02 41 01 3E
14:41.923064,CAN,0x00000000,00 00 06 41 01 7E A0 00 00 00 00 00
14:46.412504,CAN,0x00000001,00 00 02 41 01 3E
14:46.422880,CAN,0x00000000,00 00 06 41 01 7E A0 00 00 00 00 00
14:47.948231,CAN,0x00000001,00 00 02 41 02 27 01 00 00 00 00 00      //Request seed
14:47.952796,CAN,0x00000000,00 00 06 41 04 67 01 2E 66 00 00 00      //Receive seed
14:50.912555,CAN,0x00000001,00 00 02 41 01 3E
14:50.922688,CAN,0x00000000,00 00 06 41 01 7E 01 2E 66 00 00 00      
14:51.042595,CAN,0x00000001,00 00 02 41 04 27 02 B0 35 00 00 00      //Send key
14:51.052679,CAN,0x00000000,00 00 06 41 02 67 02 2E 66 00 00 00      //Key accepted
14:55.412922,CAN,0x00000001,00 00 02 41 01 3E
14:55.422497,CAN,0x00000000,00 00 06 41 01 7E 02 2E 66 00 00 00
14:59.912831,CAN,0x00000001,00 00 02 41 01 3E
14:59.922297,CAN,0x00000000,00 00 06 41 01 7E 02 2E 66 00 00 00
15:04.412804,CAN,0x00000001,00 00 02 41 01 3E
15:04.422113,CAN,0x00000000,00 00 06 41 01 7E 02 2E 66 00 00 00
15:08.009065,CAN,0x00000001,00 00 02 41 03 3B A0 10 00 00 00 00      //Write to MEC
15:08.011937,CAN,0x00000000,00 00 06 41 02 7B A0 2E 66 00 00 00      //MEC accepted
15:08.912418,CAN,0x00000001,00 00 02 41 01 3E
15:08.921923,CAN,0x00000000,00 00 06 41 01 7E A0 2E 66 00 00 00
15:13.412390,CAN,0x00000001,00 00 02 41 01 3E
15:13.421725,CAN,0x00000000,00 00 06 41 01 7E A0 2E 66 00 00 00
15:17.912372,CAN,0x00000001,00 00 02 41 01 3E
15:17.921513,CAN,0x00000000,00 00 06 41 01 7E A0 2E 66 00 00 00
15:22.412347,CAN,0x00000001,00 00 02 41 01 3E
15:22.421333,CAN,0x00000000,00 00 06 41 01 7E A0 2E 66 00 00 00
15:26.912327,CAN,0x00000001,00 00 02 41 01 3E
15:26.921125,CAN,0x00000000,00 00 06 41 01 7E A0 2E 66 00 00 00
15:27.970045,CAN,0x00000001,00 00 02 41 02 1A A0 00 00 00 00 00      //Re-read MEC
15:27.981105,CAN,0x00000000,00 00 06 41 03 5A A0 10 66 00 00 00      //MEC at 10
15:31.412368,CAN,0x00000001,00 00 02 41 01 3E
15:31.420937,CAN,0x00000000,00 00 06 41 01 7E A0 10 66 00 00 00


Ah. I just tried it on an older 2016 BCM. It worked.

They must have removed the ability to rewrite the MEC on the newer OS's.

Posts: 57
Joined: Sat Apr 25, 2020 6:09 am

Re: is this possible? copy and save oem cals

Postby Gatecrasher » Tue Feb 16, 2021 2:22 am

Maybe something related to the security changes they started implementing in the 2017 model year?

Posts: 16
Joined: Thu Feb 19, 2015 12:54 am

Re: is this possible? copy and save oem cals

Postby dmaxben » Tue Feb 16, 2021 9:25 am

Gatecrasher wrote:Maybe something related to the security changes they started implementing in the 2017 model year?


No doubt...

Just like the MY17+ BCM OS wont allow you use mode AE device control (like command lights on and off, etc) with the engine running. Only works key-on engine-off.

MY16 and older you could send one message and shut off the headlights at night while you're driving down the road if you wanted to lol.

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