Cm870 ecm went into read only mode

[Rawze]

CM870 ecm's are tricky and have quirks. They are unlike any newer ecm's, and are actually more quirky than older ones.

I have never had to resort to removing one and putting it on a bench harness. Not even in a worse case scenario where a failed or bad flash puts it in rom-boot or some other mode. It can be recovered by changing its mode back and going again. Sometimes a person has to do this though on the engine harness network and not the truck one though.

Makes me wonder who was helping you with that, as I have already helped forum member 'running rough' solve and/or prevent most of these type of tricks and traps of the CM870 ecm's and their quirks these past few years.

-= Did you try to put back in a a program that had previously been copied out? -=- that is a no-no for a CM870.

Only clean incal files can be used to flash one properly.. and then hand edit about 12 or so settings after it is installed to get the aux.emissions systems to not derate it. And even then, only certain versions of CT can be used to not corrupt the incal file if it is edited so that you don't end up in that situation.

the modes it can end up in are...

0x1D0A - rom-boot. (blank ecm with no program).

0x600D - run mode (its normal mode).

0x5EED - engineering mode (allows editing ram parameters and manual control of VG turbo, etc.).

0x2B16 - (First boot mode. Clears out old data, re-aligns the ecm to the engine again, and takes about 8 minutes to do all of its background tasks. Incal files will trigger this mode when they are flashed in.).