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DTC U0073 or U2100

DTC U0073 or U2100

Diagnostic Instructions


• Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

• Review Strategy Based Diagnosis for an overview of the diagnostic approach.

• Diagnostic Procedure Instructions provides an overview of each diagnostic category.


DTC Descriptors

DTC U0073 00

Control Module Communication Bus Off

DTC U0073 71

ECU HS Bus Off

DTC U0073 72

ECU LS Bus Off

DTC U2100 00

Controller Area Network (CAN) Bus Communication

DTC U2100 47

Controller Area Network (CAN) Bus Communication

Circuit/System Description

The serial data circuits are serial data buses are used to communicate information between the control modules. The serial data circuits also connect directly to the data link connector (DLC).

Conditions for Running the DTCs


• Supply voltage at the control modules is in the normal operating range.

• The vehicle power mode requires serial data communications.


Conditions for Setting the DTC

The control module setting the DTC has attempted to establish communications on the serial data circuits more than 3 times in 5 seconds.

Action Taken When the DTCs Sets


• The control module suspends all message transmission.

• The control module uses default values for all parameters received on the serial data circuits.

• In the TCM, DTC U0073 will cause the transmission to go into default gears.

• In the ECM and TCM, DTC U0073 will cause the malfunction indicator lamp (MIL) to illuminate.

• If the car is equipped with eAssist, DTC U0073 is a type B code in the hybrid unit. It causes the malfunction indicator lamp (MIL) to illuminate and causes the engine to work in a conventional manner and maintain 14V.

• The control module inhibits the setting of all other communication DTCs.


Conditions for Clearing the DTC


• The ECM/TCM modules turn OFF the MIL after 4 consecutive ignition cycles that the diagnostic runs and does not fail.

• If the car is equipped with eAssist, the hybrid unit malfunction indicator lamp (MIL) goes out after diagnostics run without error in subsequent ignition cycles. Normal operation resumes 5 seconds after the subsequent ignition cycle

• A current DTC clears when the malfunction is no longer present.

• A history DTC clears when the module ignition cycle counter reaches the reset threshold of 50, without a repeat of the malfunction.


Circuit/System Verification


1. Refer to Data Link References to determine which serial data system is used for a specific control module.

2. This DTC cannot be retrieved with a current status. Diagnosis is accomplished using the symptom. Refer to Symptoms - Data Communications .