On-board diagnosis function - GF07.12-P-3009HA

ENGINE 606.912 in MODEL 210.020 as of 1.6.96 with CODE (491) U.S. version

Fig 1: Identifying On-Board Diagnosis Function

Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

On-Board Diagnosis II (OBD II) functions are stored in the IFI [ERE] control module (N3/7).

Task

To detect faults in the injection system and store them in memory.

Ambient conditions prevailing at the time of the fault are also stored.

Function

Fault path tests

Under certain operation conditions, fault paths are checked for problems such as short or open circuits, implausible signals and illogical combinations.

Notes on DTC memory

DTC memory: Fault display
current fault

stored fault

All inputs and outputs are checked for plausibility during operation.

All faults that occur are stored in the DTC memory of the IFI [ERE] control module (N3/7).

The faults remain stored when the ignition is "OFF" and after disconnecting the vehicle battery.

Emissions-related faults trigger the

CHECK ENGINE

malfunction indicator lamp (A1e26) and the

CHECK ENGINE

ENGINE ELECTRONICS

indicator in the multifunction display.

The faults are marked by an OBD fault code.

Such faults include:

Lifting sender B28/3
EGR [ARF] vacuum transducer Y31/1
Pressure control flap vacuum transducer Y31/2

Fault ambient data

The fault ambient data at the time the fault was stored can also be displayed using the HHT. Only the ambient data which existed when the fault occurred for the first time is stored. The ambient data is spread over several display screens (up to 8 display screens), The last two display screens are reserved exclusively for development.

Display screens showing the result √/F point to the fault causes, such as:

Voltage too high
Voltage too low
Signal too strong
Signal too weak
Value implausible

Definition: Test readiness

Relevant fault paths and causal chains must be gone through completely at least once from ignition ON to ignition OFF (one operating cycle). Therefore two "completed" tests can only be achieved over two operating cycles.

Operating cycle

One operating cycle has been completed when

Coolant temperature > 60°C
Switch off engine
Wait 5 s for run on
Start engine
Allow engine to idle for 20 s
Rev engine in P/N to 2500 rpm and release the accelerator pedal
Set vehicle to D and accelerate to approximately 70 km/h (full throttle acceleration) and then coast to around 60 km/h.

	IFI control module location/task/function		GF07.12-P-3102HA
	CHECK ENGINE malfunction indicator lamp location/task/function		GF07.13-P-3144H
	Fault code description		dh0301p100013x