We've got a 03 FS-65 CAT 3126 w/Allison 2000 series trans, with around 85K on the odo, showing a check trans light. The prolink is showing an active code of U2105 Can Bus Error ECM and an inactive code of U2104 Can Bus Rest Counter Overrun. The bus still runs fine around town but things get interesting out on the highway. Anyone else run into this before? What should I be looking for, broken wires or parts gone bad in need of replacement? Any help appreciated, thanks
In the allison manual U2104=U0073 and U2105=U0100 bothe codes point to the J1939 data communications link between engine and trans. If you can read ecm data from the trans the code is inactive. Disconnect the batteries and check the ohms across the nine pin diagnostic connector @ pins c to d 60ohms c to e open and d to e open also check c&d to ground should be open as well. code is set on these wires yellow+ and dk green- and wire shield being grounded or open,also commonly known as the J1939 Can backbone harness. There is a 120 ohm resistor at each end of the harness, if you have more than 60 ohms on the pins one of these may be bad but most likely there is a wire rubbed through or rubbing on something causing the problem.
03 FS-65 check trans light
Posted - 10/19/2010 : 06:48:02 AM
