View Full Version : CM871 & CM876 Caution

September 30th, 2018, 11:07 AM
Hi Everyone,

This is just a cautionary warning about these two ECM's (which are essentially of the same design).
Both ECM's have very unstable reading communications, EFILive has through trial and error tried to ensure the ECM can be read all the way through successfully with error detection and handling created specifically for the bugs that exist in the OEM code. Unfortunately we've had a couple of files sent in from these ECM's where the file read out to the end but the ECM still managed to send back data from the wrong location in the ECM (I'm not even sure how such a bug could occur).
To make matters worse on these two ECM's Cummins have effectively shut off the checksums which traditionally are used to verify the validity of the data in the ECM.
So although we've managed to get the ECM to read all the way through we currently cannot ensure the data read out is 100% correct because of the lack of checksum.

The end result is our next update is probably going to disable flashing for these two ECM's until we can figure out a way to ensure the file read was correct (this is going to be very tricky).
If you were to flash in a file that did not read correctly the ECM would have to be recovered in forced ROM Boot mode, easy on the bench, not so easy if dealing with a remote customer.

EFILive suggests for the time being not to use any CM871/CM876 reads for flashing as we cannot ensure the data in there mirrors 100% what is in the ECM.


September 30th, 2018, 11:27 AM
I feel like writing is more important than reading. Personally I could care less about reading out the file that

September 30th, 2018, 12:42 PM
Writing should be fine as the ECM is executing out of bootmode at that stage and they are pretty stable then, the issue is only with the flaky read routines they have.
I understand many people already have a large base of xcal files to use for flashing so we don't want to disable it but having people brick ECM's because it read bad with EFILive isn't ideal either.

Have you had issues with read/write on the CM871 with the OEM offerings?

September 30th, 2018, 10:18 PM
Have you had issues with read/write on the CM871 with the OEM offerings?

Doesn't OEM require a config file to be loaded to read those ecm's?

September 30th, 2018, 11:48 PM
Using oem software yes many people have issues with both reading and writing. Most issues go away if u use the backbone connector (3 pin triangle shaped connector located up by the air compressor.

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September 1st, 2019, 08:21 AM
any updates to the CM871 read/flash ability?

September 1st, 2019, 08:41 AM
Yes, the latest beta has significant improvements in this regard (we bypass the factory routines).

September 1st, 2019, 08:46 AM
is this beta stabile enough to just update? I do not have another laptop available to install seperately.

On a side note, will there be tuning ability for CM871 in the future?

September 1st, 2019, 09:23 AM
The beta did only come out three days ago and it was primarily for the 2019 Dodge Ram update, so we don't really have enough feedback yet for stability assessment.
Yes there will be tuning on the older HD ECM's in the future but not in the V7 software, there will be no new controllers added to V7 from this point on, all the work being done now is for the V8 tune tool.