Allison 1000 & 2000 Gen 4 Fault Codes: U0031 J1850 (Class 2) Serial Data Communication Link Low CIRCUIT DESCRIPTION:Applications that employ J1850 class 2 serial communication use wire 130 to send operational information and commands among the various control modules. Included modules would be Powertrain Control Module (PCM), Antilock Brake System (ABS) Controller, Truck Body Controller (TBC), and Instrument Panel Cluster (IPC). Each controller sends out a state of health (SOH) message approximately once every second. The TCM uses these SOH messages to monitor the condition of the devices on the class 2 serial link. CONDITIONS FOR RUNNING THE DTC:The...

Allison 1000 & 2000 Gen 4 Fault Codes: U0032 J1850 (Class 2) Serial Data Communication Link High CIRCUIT DESCRIPTION:Applications that employ J1850 class 2 serial communication use wire 130 to send operational information and commands among the various control modules. Included modules would be Powertrain Control Module (PCM), Antilock Brake System (ABS) Controller, Truck Body Controller (TBC), and Instrument Panel Cluster (IPC). Each controller sends out a state of health (SOH) message approximately once every second. The TCM uses these SOH messages to monitor the condition of the devices on the class 2 serial link. CONDITIONS FOR RUNNING THE DTC:The...

Allison 1000 & 2000 Gen 4 Fault Codes: U0073 CAN Bus Reset Counter Overrun CIRCUIT DESCRIPTION:J1939 is the protocol currently used in medium duty applications to allow communication between an electronically-controlled engine and the OEM transmission. A signal is sent over a two-wire network harness that incorporates two 120 Ohm resistors in parallel. There are two versions of J1939 currently in use in the medium duty market. Version J1939-11, the most widely used, incorporates a third shield wire. There is also J1939-15, which uses a two-wire connection without shielding. CONDITIONS FOR RUNNING THE DTC:1. The components are powered and ignition...

Allison 1000 & 2000 Gen 4 Fault Codes: U0100 CAN Bus ECM Error CIRCUIT DESCRIPTION:J1939 is the protocol currently used in medium duty applications to allow communication between an electronically-controlled engine and the OEM transmission. A signal is sent over a two-wire network harness that incorporates two 120 Ohm resistors in parallel. There are two versions of J1939 currently in use in the medium duty market. Version J1939-11, the most widely used, incorporates a third shield wire. There is also J1939-15, which uses a two-wire connection without shielding. CONDITIONS FOR RUNNING THE DTC:1. The components are powered and ignition voltage...

Allison 1000 & 2000 Gen 4 Fault Codes: U1000 Class 2 Loss of Serial Data Communication CIRCUIT DESCRIPTION:Applications that employ J1850 class 2 serial communication use wire 130 to send operational information and commands among the various control modules. The control modules included are the Powertrain Control Module (PCM), Antilock Brake System Controller (ABS), Truck Body Controller (TBC) and Instrument Panel Cluster (IPC). Each controller sends out a state of health (SOH) message approximately once every second. The TCM uses these SOH messages to monitor the condition of the devices on the class 2 serial link. The following DTCs identify...