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Self-Diagnostic System: LH-SFI

The LH-SFI system is equipped with a self-diagnostic capability for trouble shooting. There are 2 methods of retrieving diagnostic information. Vehicles can be tested reading an on/off ratio output as a percentage to identify malfunctioning components or systems, or vehicles can be tested reading stored Diagnostic Trouble Codes (DTCs).

Stored DTC's are different depending on which module is being tested. DTC's can be retrieved from LH-SFI control unit, EZL/AKR ignition control unit, base module, Electronic Accelerator control module, Cruise Control/Idle Speed Control module, and diagnostic module. Diagnostic information can be retrieved using Pulse Counter (124 589 19 21 00) and Pulse Counter Adapter (140 589 14 63 00) or On/Off Ratio Tester (909 589 09 21 00). See Fig 1 .

Fig 1: Connecting On/Off Ratio Tester
G93G81121Courtesy of MERCEDES-BENZ OF NORTH AMERICA