On Board Diagnostic System

On Board Diagnostic System

Engine Control Modules (ECM) and Transmission Control Module (TCM) are equipped with a DTC memory.

If malfunctions occur at the emission relevant systems or components, they are stored in DTC memory with a description of the malfunction type.

Control modules differentiate between different DTCs after evaluating the information DTC tables.

The stored malfunctions can be checked with a standard diagnostic tester --> [ Diagnostic Mode 03 - Read DTC Memory ] Diagnostic Modes 01 - 09.

When connectors are disconnected from the Engine Control Module (ECM) or the batteries are disconnected, all adaptation values in the control module are erased. DTC memory content will remain intact however. If the engine is started after this, rough, uneven idle can result for a short time. In this case, the readiness code must be generated again --> [ Readiness Code ] Monitors, Trips, Drive Cycles and Readiness Codes.

The following work steps must be performed in the described sequence after the malfunction(s) have been repaired:

1. . - Check DTC memory --> [ Diagnostic Mode 03 - Read DTC Memory ] Diagnostic Modes 01 - 09.

2. . - Erase DTC memory --> [ Diagnostic Mode 04 - Erase DTC Memory ] Diagnostic Modes 01 - 09.

3. . - For completion, generate readiness code --> [ Readiness Code ] Monitors, Trips, Drive Cycles and Readiness Codes.