Not the ecm

[Mrkentee]

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.
on the dash it shows no faults with key off. Turn key on and it shows J1939 failure, and ABS J1939 failure. So it may well be an ABS module or sensor. Got someone coming in the morning with a scanner. Hopefully they find something. It’s a 2010 PB 386.
         

[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.

[1stepbehind]

ABS RELAY .....ECM RELAY. swap relays around ......no B+ power to mods no talk

check resistors possibly 1 bad or corrosion check ohms on data line like rawze suggested

tunnel vision always gets me

[Mrkentee]

(04-11-2024 )Rawze Wrote:  

(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.

J1939 seems to have 61 ohms

No clock like that

Elog is disconnected from system.

[Mrkentee]

A guy came out and got the file out of the old one and put it in the new one. Truck is running. Probably my lousy hot spot connection was the problem with the programming.