Engine Controls - Tests W/codes: Other Mercedes-Benz S-class W140

HFM-SFI (E320)

The HFM-SFI system is equipped with a self-diagnostic capability for trouble shooting. Vehicles are tested by reading stored Diagnostic Trouble Codes (DTCs). Diagnostic information can be retrieved using Pulse Counter (124 589 19 21 00) and Pulse Counter Adapter (140 589 14 63 00).

HFM-SFI (S320)

Note. Only S320 is equipped with On-Board Diagnostics II (OBD-II).

The HFM-SFI system is equipped with a self-diagnostic capability for trouble shooting. Vehicles are tested reading stored Diagnostic Trouble Codes (DTCs). Diagnostic modules are now referred to as diagnostic module (OBD-II). Diagnostic information can be retrieved using a generic scan tool or Hand-Held Tester (HHT) (965 589 00 01 00) and Multiplexer Cable (965 589 00 40 00). Control module will permit testing approximately 10 seconds after engine starting procedure is completed.

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). (Scheme 4)

Scheme 4

PRETEST CONDITIONS

Start and run engine until engine oil temperature is 176°F (80°C). Turn air conditioning off. Ensure shift lever is in Park. Check all fuses and replace as necessary. Verify battery voltage is 11-14 volts.

Note. For component locations, see THEORY/OPERATION article.

SERVICE PRECAUTIONS

When servicing S320, the following precautions must be followed when using Hand-Held Tester (HHT)

1. DO NOT connect or disconnect Hand-Held Tester (HHT) to vehicle with ignition on. Voltage is supplied to HHT through data link connector.
2. ALWAYS connect multiplexer cable to HHT first, then to data link connector.
3. DO NOT connect HHT to 110-volt or 220-volt power source.
4. Keep HHT away from strong magnetic fields, such as welding equipment.
5. DO NOT expose HHT to water, brake fluid, thinners, etc.

RETRIEVING CODES

Note. On LH-SFI vehicles, on/off ratio output is used to diagnose intermittent problems. On LH-SFI vehicles, Diagnostic Trouble Codes (DTCs) are used to diagnose hard failures. On HFM-SFI vehicles, only Diagnostic Trouble Codes (DTCs) are used to diagnose vehicle.

HFM-SFI - S320

Note. During Diagnostic Trouble Code (DTC) retrieval, CHECK ENGINE light will illuminate continuously.

Note. Before using Diagnostic Trouble Codes (DTCs) to diagnose vehicle, LH-SFI control unit must first be allowed to display on/off ratio through On/Off Ratio Tester (909 589 00 21 00).

On/Off Ratio Output (LH-SFI)

1. Turn ignition off. Perform pretest conditions. See «PRETEST CONDITIONS»(ref-14861-S14099108432000122900000) under SELF-DIAGNOSTIC SYSTEM. Connect On/Off Ratio Tester (909 589 00 21 00) to diagnostic connector located on left fender apron. (Scheme 4) Malfunctions are distinguished between failures which occur with ignition on, engine off and with engine idling.
2. Only on/off ratio readouts can distinguish between failures which occur with ignition on, engine off and with engine idling. Turn ignition on with engine off or allow engine to idle. Record on/off ratio. See appropriate table under ON/OFF RATIO IDENTIFICATION.

Scheme 5

1. Turn ignition off. Perform pretest conditions. See «PRETEST CONDITIONS»(ref-14861-S14099108432000122900000) under SELF-DIAGNOSTIC SYSTEM. Before using DTCs to diagnose vehicle, LH-SFI control unit must first be allowed to display on/off ratio through On/Off Ratio Tester (909 589 00 21 00). See ON/OFF RATIO OUTPUT (LH-SFI).
2. Connect Pulse Counter Adapter (140 589 14 63 00) to diagnostic connector located in right rear corner of engine compartment. Connect Pulse Counter (124 589 19 21 00) to pulse counter adapter. (Scheme 5) Connect Red wire of pulse counter to pulse counter adapter terminal No. 3. Connect Black wire of pulse counter to pulse counter adapter terminal No. 1.
3. Pulse counter Yellow wire is connected to pulse counter adapter depending on which module is being tested. DTCs are different for each module on vehicle. See PULSE COUNTER CONNECTION/ADAPTER IDENTIFICATION table. PULSE COUNTER CONNECTION/ADAPTER IDENTIFICATION Module Adapter Terminal Base Module (1) No. 8 Cruise Control/Idle Speed Control Module (2) No. 7 Diagnostic Module (3) No. 19 Electronic Accelerator Control Module (4) No. 7 EZL/AKR Ignition Control Unit No. 17 LH Control Unit No. 4 (1) Base module will identify voltage supply malfunctions, A/C clutch, poly-V belt slipping and module box temperature. (2) Vehicles without Acceleration Slip Regulation (ASR). (3) Diagnostic module will identify malfunctions for all modules. (4) Vehicles equipped with Acceleration Slip Regulation (ASR).
4. After connecting Yellow wire to proper pulse counter adapter terminal, U-BATT LED on pulse counter display will illuminate if equipment is properly connected. If U-BATT LED illuminates, go to next step. If U-BATT LED does not illuminate, check pulse counter fuse. Replace as necessary. If pulse counter fuse is okay, check wiring harness between diagnostic connector and vehicle wiring harness. Repair wiring as necessary.
5. Start engine and idle. Press START button on pulse counter for 2-4 seconds maximum. Pressing push button longer than 2-4 seconds will erase code in memory. Read pulse output on pulse counter. If pulse counter displays "1", no faults are stored. If pulse counter displays a number greater than "1", faults are stored.
6. Press start button again for 2-4 seconds. If more fault codes are stored, pulse counter will display next code. Continue pressing start button for 2-4 seconds at a time until pulse counter displays first fault again. Record all fault codes. See appropriate table under «LH-SFI FAULT CODE IDENTIFICATION»(ref-14861-S31155091952000122900000) to identify fault code.

Disconnect vehicle battery. Stored DTCs are now erased. If DTCs are retrieved again before operating vehicle, DTC No. 1 will not display until HFM-SFI control unit sees system is functioning properly. After HFM-SFI control unit sees system is functioning properly, DTC No. 1 will be displayed.

DTC memory can be cleared using generic scan tool or Hand-Held Tester (HHT). After clearing DTC memory, using generic scan tool or HHT, give "end" command and turn ignition off for approximately 5 seconds. Turning ignition off for approximately 5 seconds allows DTC memory to be overwritten. An alternative method of clearing DTC memory is to disconnect vehicle battery.

1. Disconnecting vehicle battery will not erase codes. Connect Pulse Counter Adapter (140 589 14 63 00) to diagnostic connector, located in right rear corner of engine compartment. Connect Pulse Counter (124 589 19 21 00) to pulse counter adapter. (Scheme 5) Connect Red wire of pulse counter to pulse counter adapter terminal No. 3. Connect Black wire of pulse counter to pulse counter adapter terminal No. 1.
2. Pulse counter Yellow wire is connected to various pulse counter adapter terminals, depending on which module is being cleared. See PULSE COUNTER CONNECTION/ADAPTER IDENTIFICATION table. PULSE COUNTER CONNECTION/ADAPTER IDENTIFICATION Module Adapter Terminal Base Module No. 8 Cruise Control/Idle Speed Control Module (1) No. 7 Diagnostic Module No. 19 Electronic Accelerator Control Module (2) No. 7 EZL/AKR Ignition Control Unit No. 17 LH Control Unit No. 4 (1) Vehicles without Acceleration Slip Regulation (ASR). (2) Vehicles equipped with Acceleration Slip Regulation (ASR).
3. After connecting Yellow wire to proper pulse counter adapter terminal, U-BATT LED on pulse counter display will illuminate if equipment is properly connected. If U-BATT LED illuminates, go to next step. If U-BATT LED does not illuminate, check pulse counter fuse. Replace as necessary. If pulse counter fuse is okay, check wiring harness between diagnostic connector and vehicle wiring harness. Repair wiring as necessary.
4. Turn ignition on. Press START button on pulse counter for 2-4 seconds maximum. Wait 3 seconds. Press START button on pulse counter for 6-8 seconds. Turn ignition off and wait 30 seconds. Each code stored in must be erased individually. Repeat procedure for other stored fault codes. When pulse counter displays "1", no faults are stored. Disconnect test equipment.

LH-SFI CONTROL UNIT ON/OFF RATIO ID (IGNITION ON, ENGINE OFF)

LH-SFI CONTROL UNIT ON/OFF RATIO ID (ENGINE IDLING)