I have a 2006 6.0L F250. I was pulling a trailer today with a small excavator on it down the highway at 70 mph and the wrench light came on. I have had this happen one other time hauling a trailer. I lerft the truck on this time and ran the DTC and got the U1900. What does this mean? What can i do to fix it? The truck misses at times at WOT, but does it randomly. But even when that hapens, the light doesnt come on and it doesnt go into limp mode. If you shut the truck off and start it again, it'll be back to normal... If that helps any

 

Possible Causes
CAN circuit 1908 (WH) open, short to ground, or short to voltage.
CAN circuit 1909 (BK) open, short to ground, or short to voltage.
DLC C251
ABS module
ABS module C135
instrument cluster
instrument cluster C220b
PCM
PCM C175b or C1381b
trailer brake controller
trailer brake controller C2142b

Things to check first:
You could have a bad ground on your trailer.
Your cable on your trailer could be too short and causing it to pull out of the plug
You could have a short in the factory trailer harness wiring
The plug could be gunked up

Also, check for loose fuses:
#11, 10 amp: Speedo bounce, ABS light, Cruise control inop; Codes U1900, U2023, P0500-P0503
#12, 2 amp: Cruise control inop, TBC Fault displayed, chime; Code C2803

 

u1900 more thenk likly means what your reading codes with is not see what the real code is.
u1900 is a network falt.
you need a scan tool with the latist dtc files to read those codes that kick the wrench light. then its still iffy if you can.

 

so next time im hauling and it comes on, just take it to the dealer? Thats the only time iever see the darn thing is while pulling a trailer

 

yup once it kicls on again it will store the code. just dont clear any codes. dont need a trailer.

 

cheezit -

Why couldn't bad trailer wiring (ground issue, etc) cause this code?? Or is it more likely to be a false code?

 

heheh will I guess it in theory could but.... wait for it..
a u1900 should not produce a wrench light

 

also the u1900 is useless with out the added info of what module has produced the network fault.

 

Makes sense - THANKS!

 

Thing is, is that i never gotten the wrench light just driving. Its been with a trailer the only 2 times its ever come on

 

Sorry to undig a dead thread... since the beginning, I have gone through the top end with studs, and cleaned the turbo. The wrench light no longer comes on but on long hauls with a trailer, she sometimes likes to miss on the top end. Sometimes. Almost like it starves for fuel. Others, its perfectly fine. Fuel pressure is at 68 psi and stays there even at WOT and an sct tuner. Also have a AD2 and blue spring. Code is still there and my a/c no longer works... wonder if they are related in a way

 

I have a 2006 F250 6.0l lariat when i start it cold it smokes white until the engine is at operating temp. I just purchased this truck and it had a bully dog tuner on it. the truck would start but run very rough for a couple minutes and smoke white. I flashed the ecm back to stock and its only runs rough for a couple secs now but the smoke has gotten way worse. i am concerned that its a head gasket as i had to put 2, 4L jugs of antifreeze in it since i got it, it has a stored code u1900 i think many an ficm issue from the bully dog