Cm 870 turbo actuator control module

[Slappy]

I have the 2006 engine model cm870 Cummins. Running down the road I noticed my volt gauge would drop and cycle between a normal 13.6 to 12 volts then run fine and start to do it again. Then the turbo control box started popping off air,I thought the turbo module may be going out and dropping voltage trying to adjust pressures. I’ve replaced the module and the same thing is happening. Beginning to think I’ve got a short/grounding issue. Anyone know the wiring schematic for turbo module as I do not have insight. Thanks

[Rawze]

could also be the alternator or a battery going bad?.

[Slappy]

So,little update..I’ve checked out and load tested all the batteries,checked out all my grounds and alternator. Everything is good and voltages are normal. I’ve tested 3 turbo control boxes on unit and the same thing is happening every time. I have torn the wiring harness apart and found nothing…completely stumped. Truck ran great til this starting happening and has a 2 year old Cummins recon ecm with no codes.

[Rawze]

(12-26-2025 )Slappy Wrote:  So,little update..I’ve checked out and load tested all the batteries,checked out all my grounds and alternator. Everything is good and voltages are normal. I’ve tested 3 turbo control boxes on unit and the same thing is happening every time. I have torn the wiring harness apart and found nothing…completely stumped. Truck ran great til this starting happening and has a 2 year old Cummins recon ecm with no codes.

what are the actual turbo-specific related symptoms?.. your first post was a bit vague. Boost spiking and dropping back?>,. or what?.

and has anyone moved the control arm for the turbo to ensure its not hanging up and operates smoothly?.


Is the programming completely factory?... or is it a de-mandate program?.

[Slappy]

To start over. 07 international 9400 with a 06 cm870. Truck is completely factory, set at 475 hp with all systems operating and no modifications. Truck has ran great for the most part with exception to cleaning some egr stuff through the years. Driving along truck would drop voltage from 13.8 to 12 and less,cough out a huge plume of smoke til the volts climbed back up and run fine. It’s done this a few times the past month but would be intermittent and run fine after. However two or so weeks ago running along interstate empty it started to loose voltage then return to normal constantly but then the turbo control box started popping off air making me think it was it causing problems. Put a new reman turbo box on and same thing,tried another good used box and same. Use to be intermittent but now is constant even at idle. Thought it maybe egr valve and pulled plug but no change. Truck hasn’t thrown any codes for anything . I’ve been tearing apart wire harness and found 1 small rub through but it didn’t change anything. Something is not right and I’m pulling my hair out. I checked the wiring for turbo control box leads and it shares a ground with the pick up fuel pump which is all good so it’s not that. Something has to crossings over somewhere that effects that circuit along with egr circuit is my guess…only a guess which is terrible.

[Rawze]

Corroded or bad wiring from alternator to starter?.

Bad/corroded wiring from alternator (or starter) to batteries?.

Bad battery disconnect switch?.

The main voltage in the vehicle jumping from 13.6 to 12 (or below) is NOT going to be some turbo wiring, but a power cable issue somewhere.

and if you did not get faults for disconnecting the egr valve, etc... then you have a delete file in it. - Put the latest factory programming back in it and straighten out any faults that come up before trying to find ghost issues with boost, turbo, etc. - For all anyone knows, associated fault(s) very well could have been surpressed by crappy delete programming, making it exponentially more difficult to find an issue.

[DVT873]

International likes to use the hot post on the starter as a junction point. Take the nut off and remove all the wires, and inspect them. The ring terminals like to break, or the nut gets loose. You have to take it apart to get a good look.
Also look for a 3 wire flat connector body. Probably around the starter. usually has 2 12G red wires and a 12G white wires. Take it apart. Often the terminals are messed up. If they are the connector body can be cut out and the wires spliced together. See problems there all the time on the medium duty Cornbinders.      

[Slappy]

Thanks for all the replies and help. Ended up running new power supply line to ecm and so far it corrected the problem. I had replaced those lines and plug 3 years ago when I replaced the ecm . The old wires look great but don’t mean jack. Thanks again