U2103

Can Link Diagnostic Codes (Start Here For U2100 THRU U2107)

Diagnostic Chart:

Schematic:

The engine control module (ECM), transaxle control module (TCM) and the body control module (BCM) communicate with each other over the controller area network (CAN) bus circuit 2501 and circuit 2500. The CAN bus is a communication link similar to Class II.

State of health (SOH) messages are sent from all the CAN controllers when the ignition is turned On and during vehicle operation. These messages tell the BCM, TCM and ECM that all are working correctly. The BCM and ECM have an internal reset counter to monitor the status of the CAN bus. When the counter reaches a defined value and no CAN messages have been received from either the ECM. BCM or TCM, the ECM or ECM sets DTC 2104.

DTC U2100 - Can Bus Communications Malfunction
This DTC is only implemented in the ECM and is used to detect CAN Link Hardware Faults such as CAN High or CAN Low Link.
^ Shorted to ground
^ Shorted to a voltage source
^ Shorted together

DTC U2103 - FEWER Controllers On Bus Then Programmed
This DTC is only implemented in the ECM and will always be set along with a specific controller missing DTC.

DTC U2104 - Can Bus Reset Counter Overrun
This DTC can be set by any module connected to the CAN Link and is set when no CAN messages are being received by a module.

DTC Parameters
^ Ignition in RUN or START position.
^ CAN bus reset counter has reached a defined value.
^ This code will always set along with with a specific module missing code. U2105, U2106 or U2107.

DTC U2105 - Lost Communications With Engine Control Module (ECM)

DTC Parameters
^ Ignition in RUN or START position.
^ Loss of communications with ECM.
^ This code can be set by the TCM and BCM.

DTC U2106 - Lost Communications With Transaxle Control Module (TCM)

DTC Parameters

IMPORTANT: Engine must be running or cranking for greater than 5 seconds for the ECM to set this code.
^ Ignition in RUN or START position.
^ Loss of communications with the TCM.
^ This code can be set by the BCM and ECM.

DTC U2107 - Lost Communication With Body Control Module (BCM)

DTC PARAMETERS

IMPORTANT: Engine must be running or cranking for greater than 5 seconds for the ECM to set this code.
^ Ignition in RUN or START position.
^ Loss of communication with the BCM.
^ This code can be set by the ECM and TCM.