CM 871 won’t regen

[JimT]

(12-11-2019 )theironoracle Wrote:  I completed the trouble shooting in Insite. It ends at replace harness if that doesn’t fix it replace ECM. The harness is a month out so I installed the ECM and it didn’t change. Fails the heater test every time. I did my own harness testing looking for shorts to power, ground and resistance and really don’t see anything wrong with the harness. I’m think about installing new heaters thinking they may fail when power goes to them even though they pass the ohms tests. Any info would be appreciated!!! Cummins tech support literally laughed at me when I asked for operating peramiters of the system. Thanks TIO

I had the same codes pop up few months back on my 2012 pete cm2250.

not sure about the truck you have there, but on mine there is a small fuse holder and relay in the battery box that powers the DCU. fuse was fine, relay was fine. was about to test the harness when i found one of the pins inside a deutsch connector (just after the relay) was corroded. got replacement pins from dealer, changed the bad pin and all was good.

had to look close for that one. because the corrosion was hidden where the pin and wire met inside the connector, it would sometimes work when i shoved the probe in to test. After a couple tries I figured i'd need to move on to testing the DCU, then the wire pulled out of the back of the connector! Lucky break.

hope this helps.

edit: code 3562 should have caught your attention. note that all 3 line heaters are powered from a single relay which is controlled by a single circuit to the DCU. Even if all 3 line heaters went bad at the exact same time, you still have the short on the control circuit.