Engine Controls - Self-Diagnostics: Other — Mercedes-Benz C-class AMG W202 facelift (1997-2000)

PRODUCTION DATE INFORMATION

Note. This diagnostic information applies to 1997-99 models with engine 104 (inline 6-cylinder) equipped with Motor Electronics Sequential Fuel Injection (ME-SFI).

Some diagnostic information is divided by vehicle production date breaks. Be sure diagnostic information being used applies to vehicle being diagnosed. The following production date break is used in this diagnostic information.

Some information applies to C280 (model 202), E320 (model 210), S320 (model 140) and SL320 (model 129) as of 9/97.

Mixture Self-Adaptation

The engine control system is capable of precisely regulating air/fuel mixture at a constant 14.7:1 under all engine operating conditions. If an air leak, injector wear, injector carbon build-up, engine wear, transition resistance in Mass Airflow (MAF) sensor, defective pressure regulator or defective purge control valve are present, the Engine Control Module (ECM) can automatically perform mixture adjustments.

The amount of correction is constantly calculated and permanently stored. Self-adaptation additive is performed at idle. Self-adaptation multiplicative is performed under partial load. Correction towards rich or lean is ±1.0 milliseconds (injection duration) at idle or factor of .68-1.32 at partial load. After a repair, the ECM will automatically adapt again.

Throttle Valve Actuator Recognition

The end stops (closed throttle) and Wide Open Throttle (WOT) are determined by the throttle valve actuator and stored by the Engine Control Module (ECM). After replacing an ECM or actuator, mechanical stop and WOT must be determined and recorded again. Current learned data must be erased using scan tool.

When a new ECM is connected to vehicle for the first time, ECM performs a self-adaptation of lower mechanical end stop when ignition is first turned on.

The following requirements must be present for ECM to self-adapt to lower mechanical end stop

Transmission in Park or Neutral
Vehicle not moving
Engine off
Engine coolant temperature 41-212°F (5-100°C)
Accelerator pedal not depressed

When all conditions are met, turn ignition on for at least 60 seconds, then turn ignition off for at least 10 seconds. The learned value is stored in memory only after the first 10 start cycles. If battery voltage is disconnected after the 9th start cycle, the re-learn process must be performed again.

Crankshaft Position (CKP) Sensor Adaption

After replacing an Engine Control Module (ECM), Crankshaft Position (CKP) sensor, starter ring gear, motor mount, after performing uneven running engine test, sensor adaptation must be performed. Run engine until coolant temperature is more than 158°F (70°C). Drive vehicle. With gear selector in position 4, increase engine speed to approximately more than 2500 RPM, then coast until engine speed is less than 1500 RPM. Change gear selector to position 2. Increase engine speed to approximately 6100 RPM, then coast until engine speed is less than 4100 RPM. Again increase engine speed to approximately 6100 RPM, then coast until engine speed is less than 3000 RPM. Using scan tool, verify VSS adaptation has occurred.

CHECK ENGINE LIGHT

The ECM is equipped with Diagnostic Trouble Code (DTC) memory. Malfunctions are stored as constantly present or intermittent (occurred during a trip). DTC memory is erased when battery is disconnected. Malfunctions which are no longer present are erased as follows: after 3 trips CHECK ENGINE light goes out and after an additional 40 warm-up periods, DTC is automatically erased.

A warm-up period is defined as engine coolant temperature less than 95°F (35°C) at engine start with engine coolant temperature increasing to more than 176°F (80°C). A trip is defined as follows

Engine running for more than 20 minutes
Engine oil temperature more than 19°F (-7°C)
Engine speed more than 500 RPM
All emission related logic chain functions were checked during previous trips

VERSION CODING

Note. Hand Held Tester (HHT) is necessary for performing version coding.

The Engine Control Module (ECM) has a version coding feature. Coding must be performed when a new ECM is installed. Version coding can be performed automatically or manually using Hand Held Tester (HHT).

Automatic Coding

Before removing Engine Control Module (ECM), using HHT, read and store existing version code. After installation of new module, download previous version code using HHT.

Manual Coding

If version code number cannot be read, vehicle equipment and version must be determined. A corresponding code number must be obtained from Spare Parts Microfiche and manually entered with HHT. The following version data must be obtained for coding

Vehicle model
Engine
Transmission
Non-catalytic converter
Country version
19 MPH (30 km/h) limitation

DRIVE AUTHORIZATION SYSTEM (DAS)

Note. This diagnostic information applies to 1997-99 models with engine 104 (inline 6-cylinder) equipped with Motor Electronics Sequential Fuel Injection (ME-SFI).

DAS is activated from DAS control module through the Controller Area Network (CAN) data bus to the Engine Control Module (ECM). When DAS is activated, ECM renders fuel injection system inoperative. See DAS VERSION table to identify model/version usage.

Year	Model	DAS Version
1997	C280, C36, E320 & SL320	DAS X
1997-99	S320	DAS X
1998-99	E320	DAS 3

DAS VERSION

DAS X activation or deactivation is accomplished with a transponder in the ignition key. When ignition is turned to lock, DAS X control module is activated. When electronic key is inserted into the ignition lock, DAS X control module is activated. Locking or unlocking vehicle using mechanical key has no effect on DAS.

DAS 3 activation or deactivation is accomplished with the electronic key. When electronic key is inserted into the ignition lock, DAS 3 control module is activated. Locking or unlocking vehicle using mechanical key has no effect on DAS.

On DAS systems, the Engine Control Module (ECM) and DAS control module are "married" to one another with identification codes. Identification codes cannot be erased. Switching ECM or DAS modules form one vehicle to another is not possible. If an exchange ECM is installed for test purposes, up to 40 start attempts can be performed before ECM and DAS control modules "marry" to one another. Prior to performing first engine start, ECM must be version coded to vehicle using scan tool. See VERSION CODING .

SERVICE PRECAUTIONS

WARNING

DO NOT perform testing or repair procedures on ignition system if you have a heart pacemaker.

Turn ignition off before connecting or disconnecting Engine Control Module (ECM) connectors.
DO NOT ground ignition coil No. 1 (i.e., theft deterrent).
When cranking or idling engine, DO NOT disconnect ignition coil cable or spark plug cable.
Ignition system high output side must carry at least 2 k/ohms of load.
Turn ignition off when connecting or disconnecting test equipment at ignition coil.
DO NOT connect a test light to ignition coil circuit No. 1 or 15.
When performing an ignition spark test, check one spark plug at a time and ensure spark plug is grounded.

RETRIEVING CODES

Note. Diagnostic information is read using a generic scan tool or Hand-Held Tester (HHT) (965 589 00 01 00) and Multiplexer Cable (965 589 00 40 00). HHT and multiplexer cable are preferred. Generic scan tool may not be able to perform all test functions.

Using Hand Held Tester (HHT)

Turn ignition off. Connect HHT to 38-pin diagnostic connector located in right rear of engine compartment. Turn ignition on. Follow manufacturers instructions for reading fault codes. If no fault codes are present, but vehicle is experiencing a problem, go to SYMPTOM DIAGNOSTICS .

CLEARING CODES

Disconnect vehicle battery. Stored DTCs are now erased. Stored DTCs can also be erased using Hand-Held Tester (HHT) (965 589 00 01 00) and Multiplexer Cable (965 589 00 40 00). Follow equipment manufacturers instructions.