Hey guys, not a Cummins but I gotta talk to someone. I inherited a mess. Another tech installed a used engine in this Cascadia and it wouldn't crank. Turns out it's got some delete and also he cut some communication and other wires. I've for the wires all put back together and it starts but there's no throttle and it sets a 625 FMI 14 right away. I went down the diag tree and got to the end where it said to replace the MCM. The used engine came with a controller so I swapped that on but no change. Then I talked to a guy at the dealership who sold me on a reman CPC. Well that didn't fix it either. Any help would be awesome.
what year ? if it been demandated that means the acm and the engine ecm from the original truck have been modified.
if you have a modified file in the engine but not in the truck acm then you will have issues.
2012 is the year. the mcm is the same, we just swapped it with the controller that the used engine came with, so it should be the same file. ACM and MCM are the original pair. Yesterday I tried a new CPC and got the same code. I tried using the used engines mcm just to see if that changed anything but it didn't. Same code.
Check the harness by the air compressor, they are notorious for rubbing through there. Also that code is a communication code for loss of communication to the mcm if I’m not mistaken, may wanna double check and make sure the j1939 was repaired properly.
ive run though the normal stuff. everything is insulated, powered and grounded. unless my shopkey information isnt accurate its wired correctly. thats why im here, im out of ideas. is it possible that the mcm could have lost its ehemm "tune"?
I’ve never seen an mcm loose a tune or programming unless it’s been re flashed for one reason or another. You may need to check your star point connector behind where the dog house cover is, also something else to check is water intrusion from the cab lights or the visor. I’ve seen the Tps sensor get water in them and the Sam cab module is notorious for water damaging them from this.
check your cpc modules , got white or yellow labels , some have 250k and 500k baud rate, so truck will start but not work correctly, i would bet on bad cpc as i had replaced around 50 of them, truck is manual or auto? if truck starts your can line should be ok, ohm diagnostic port on can bus with key of to see if you have 60ohms, maybe missing resistor,
or with dddl at cylinder cutout you can adjust rpm manually see if this works , it would confirm you can command mcm to raise rpm
What year was the original engine and what is is the new one installed ? What was the failure of the old engine? Something isnt adding up here. This seems like a software issues because of the communication issues. The other issue is the de mandate. If both the mcm and acm from the original engine are not used you will have the communication issues.
Are you able to reflash the mcm and acm back to a stock file ?
Another question can you idle the truck up with the cruise ship to fast idle switch?
thanks guys. to answer the questions, the cruise will not raise idle, the original engine locked up, I dont have the capabilities to flash modules(we have the issue of the shmedeleteshmesh to deal with too), I dont know the year of the replacement engine (customer provided) I could find out but dont know right now, I am using the trucks MCM and ACM Ive got a reman CPC but it didnt make any difference so I plugged the old one back in, it is a manual trans.
I checked the DLC connector for resistance readings this morning. H to J I have 60 ohms but the C to D I have 134 ohms. Im guessing this is the problem? I looked at the diagram and I cant say weve disturbed anything on that circuit but something must be off. Also I checked voltage from pin A to pin C 2.45v, spec says 2.6v. Pin A to pin D is 2.15v, spec says 2.3v. Enough of a difference to make a difference? My battery voltage was a little low so I put the charger on it battery voltage at 13.2v didnt change my readings.
Im guessing I need to chase down the resistance on the 1939? Most of the time I work on cars but this seems like it would be considered the "high speed" network? Im not sure if its the same terminology but engine, trans, ABS, air bag, and cluster run on high speed and HVAC, door modules, rear view camera,ect run on low speed. Can one network affect the other on these trucks?
also my gauges arent working except for the volt meter and I cant communicate with them either