OK, I went over there to the My Freightliner first thing this morning and decided to check a few things out with the mechanic working on getting my INOP N14 that should be gone over; I have personally located and checked the ECM fuses, they are good. I checked the battery connections and they seem to be good. Checked condition of wiring harness and connectors, OK. Ground connection seems to be solid and clean.
There is a 3 volt drop between the battery terminal voltage and the two always-hot wires going to the ECM, but the mechanic here says that's not enough of a drop for major concern.
Checked voltage and operation of fuel solenoid; OK
The check valve that is at the entry port of the cooler plate behind the ECM was not functioning, apparently. The replacement valve has not arrived yet, but I suggested we get the plate ready for it, so we pulled the ECM (mounted to the plate) and found a bigger problem; The cooling plate itself is cracked, and there was a considerable amount of fuel that had leaked from this, apparently. The back of the computer had some old dirt and grease on it, and it seems when the last mechanic reinstalled the computer to the cooling plate, this should have been cleaned off, and the pressure from the foreign matter has cracked the cooling plate, and now THAT needs replacing as well; another day now waiting for a danged part...
I'm looking into other things that this could be: Investigating that voltage drop is job 1. it shouldn't be that much of a drop as there is no resister inline. Number two is to make sure the engine sensor is in good shape and not contaminated.
The ECM lights stay on while cranking. that's a good thing, as if it were a low-voltage problem the lights would NOT come on while cranking. Also I have to check to see if the new cooling plate will come with all of its valves and ports pre-installed. YAY.
I'm NOT having fun at this. I feel like my free time is being taken away from me and HAS been taken from me three loads in a row. Sure, I know it's an expense to be getting the truck repaired, but I am ALSO incurring expenses here that apparently I will never be reimbursed for. I don't mind the occasional effort to "help the company out" , but don't you agree, this is getting a bit ridiculous?
Frazzled and frustrated,
Tom

well i am no big truck techie, but i do know that a 3volt drop is bad. if i remember school, its like 1/10th of a volt per foot is ok. another thing is just because it check ok resistence wise, doesnt mean it is ok load wise. try overlaying the power feed first and formost. i have had plenty of 6.0s and 7.3s and many gas jobs crank over perfectly and never start because voltage was to low. 10volts will still spin a starter but when you have numerous feeds on a line, it will drop below 9.6 which is required for a ford pcm to initialize. now, i dont know what your voltage is or any details about it but nowadays, it is always electrical then mechanical in all of my thoughts when diagnosing any issue.

good luck

Thanks... that was what was puzzling me, but the Cummins people swear it will operate down to 6.5 volts. That is STILL a big drop, and I'm looking into new harness sections now!

Yes, No, Maybe...


It has to be one of the above answers. (possibly anyway).

I agree, thats a large drop. If they are going to be content with you doing major work on the truck, they ought to at least supply an electric schematic. Any hidden loads between the battery and the ecm? Remember how the old Chevvy battery cables would corrode internally? If you disconnect the ecm, is there still a drop?

It may run with 6.5 volts but i am guessing it wont run well, and may never start with low voltage.

A 3 Volt drop is huge in a 12Volt system (25%), that large of voltage drop is not good on any electrical appliance and especially not good for a computer. That 3 Volts has to be bleading off somewhere and i am with Vince on this i would definitely look for bad wiring (ie wires with high internal resistance).

Good luck