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DTC C078A

DTC C078A

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 C078A 39

Tire Pressure Indicator Module Internal Malfunction

Circuit/System Description

Control module fault registration is handled internally in the K65 tyre pressure indicator unit. No external circuit diagnosis is involved.

Conditions for Running the DTC

The indicator unit runs the program to detect an internal fault when power up is commanded. The only requirements are voltage and ground. This program runs even if the voltage is out of the valid operating range.

Conditions for Setting the DTC

The indicator unit has detected an internal malfunction.

Action Taken When the DTC Sets

The indicator unit refuses all additional inputs.

Conditions for Clearing the DTC


• 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.


Diagnostic Aids


• This DTC may be stored as a history DTC without affecting the operation of the indicator unit.

• If stored only as a history DTC and not retrieved as a current DTC, do not replace the indicator unit.

• If this DTC is retrieved as both a current and history DTC, replace the indicator unit.


Circuit/System Verification

Verify that DTC C078A is not set.

If the DTC was triggered, replace the K65 tyre pressure indicator unit.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

Control Module References for module replacement, setup, and programming