Not the ecm

[Rawze]

(04-11-2024 )Mrkentee Wrote:  I have a J1939 connection problem that won’t let the truck start.
I’ve checked fuses and wiring, etc.
Put new ecm in, started right up. Ran for 10 minutes. Hooked up my trailer, drove 8 minutes to truck stop.

..While being reprogrammed lost connection. Now won’t start again.

...

Did you manage to finish re-flashing it after the lost connection?. If not then the ecm will not run the truck at all. Only a completed flash to 100% will allow it to run again.

(if you are able to re-flash it) ... What happens if you flash the factory file back into it?.

Has anyone checked to see if there is a proper 50-ohms on the J1939 network?.

Does is stop acting up when you unplug your e-log device?.

Does your truck has a factory clock?. Most factory/dash clocks are not tied to the J1939 network, but on some model trucks they actually are. If this is the case, it is possible for the clock to act up and interrupt J1939 communications and give problems. It would be extremely rare, but it has happened to a couple people on the forum here in the past.