2009 Cummins ISX CM871 communication error? or not?

[Rawze]

What you describe is typically one of 2 things.

A known wiring issue that Pete and KW trucks suffer. read this post...
ref: http://rawze.com/forums/showthread.php?t...05#pid3505

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OR.. a bad/flaky ecm.

If that ECM was not purchased form a stealers#$it and from some place that does repair etc. or online.. then you very well could have another bad ecm on your hands. - i know of one person on that went thru 4 of them, 3 of which were NOT from OEM .. before they got a certified one from a stealeres$it and all his issues went away.

And even if you got one from a stealers$it there is still a chance you got a bad one.. though it is far more rare.

The CM871 ecm's are notorious for getting flaky like that and cutting out .. but there is a way to test them.. By hitting it with screwdriver of socket extension bar. here is some detail...
ref: http://rawze.com/forums/showthread.php?t...7#pid76607