U0140

DTC U0140

CIRCUIT DESCRIPTION
Modules connected to the CAN serial data circuits monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the modules. The modules have prerecorded information about messages exchanged on the serial data circuits. The supervised and periodic messages are used by the receiving module as an availability indicator from the transmitter module. Each message contains the identification number of the transmitting module. When a message indicates availability of the transmitting module is not received, the receiving module sets a DTC Uxxxx; where xxxx is equal to the 4-digit transmitter module identification number.

The control module ID number list below provides a method for determining which module is not communicating. Modules with CAN serial data circuit malfunctions, or which loses power during the current ignition cycle, will set a Loss of Communication DTC by other modules requiring information from the failed module. The modules able to communicate will set a DTC Uxxxx indicating the module not communicating.

CAN ID:

If any of the CAN circuits are shorted to battery voltage, ground or between them, no communication is possible on CAN serial data bus, and a DTC U0073 sets.

CONDITIONS FOR RUNNING THE DTCs
- Voltage supplied to the modules are in the normal operating voltage range.
- The vehicle power mode requires serial data communication to occur.

CONDITIONS FOR SETTING THE DTC
A receiving module did not detect the CAN serial data supervised periodic message from a transmitting module.

ACTION TAKEN WHEN THE DTC SETS
The module uses a default value for the missing parameter.

CONDITIONS FOR CLEARING THE MIL/DTC
- A current DTC and MIL clear when the malfunction is no longer present.
- A history DTC clears when the module ignition cycle counter reaches the reset threshold, without a repeat of the malfunction.

DIAGNOSTIC AIDS
- A poor connection at the inoperative module may cause this code to set.
- A module that loses its connections to battery, ground or switched ignition may set this DTC.

TEST DESCRIPTION

Steps 1-6:

Steps 7-8:

The numbers below refer to the step numbers on the diagnostic table.
1. A total loss of communication on CAN serial data link should be diagnosed first.
8. The modules which can communicate indicate the module which cannot communicate. You must clear the DTC from these modules to avoid future misdiagnosis.