[EUROPEAN OBD, Function - GF07.10-D-1021TSA

Engine 651 in model 907 

Function requirement for European On-Board Diagnosis (EOBD), general points 

• Circuit 87M ON (Engine management ON)

European OBD (OBD), general 

An On-Board Diagnosis system of the second generation (OBD II) is used. In Europe the OBD II, with appropriate adaptations for the European market is called European OBD (EOBD). The EOBD system is integrated in the CDI control unit and constantly monitors all exhaust gas relevant components and systems of the vehicle.

• The EOBD has the following tasks:
  • Monitor emissions-relevant assembly parts and systems while driving.
  • Establish malfunctions and save them.
  • Display the malfunctions via the engine diagnosis indicator lamp (A1e58)
  • Detected faults are transmitted via a uniform interface (diagnostic connector) to a diagnostic unit (e.g. XENTRY Diagnostics).

EOBD pursues the follow objectives:

• Achieving permanently low exhaust emissions.
• Protect assembly parts at risk (such as the catalytic converter).

The following assembly parts and systems are monitored:

• Intake air path
• Fuel system
• Glow system
• Exhaust gas recirculation
• Smooth running control
• Oxygen sensor
• Oxygen sensor heater
• Diesel particulate filter
• AdBlue® system
• Crankcase ventilation system
• Cooling system
• Other emission-relevant components or components whose malfunctioning prevents the diagnosis of another component.

The following are monitored over function chain tests:

• Smooth running control
• Exhaust gas recirculation
• Oxygen sensor heater

Function sequence for cyclic monitoring 

Cyclic monitoring takes place for components and systems which are not permanently active. Regeneration, for example, only takes place when the vehicle is being operated under partial-load conditions and can therefore only be monitored during this operating phase.

The following components and systems are monitored cyclically:

• Fuel system
• Exhaust gas recirculation
• Smooth running control
• Oxygen sensor
• Oxygen sensor heater
• Regeneration

Function sequence for continuous monitoring 

Continuous monitoring means continuous monitoring from engine start to "ignition OFF".

The following components and systems are monitored continuously:

• Intake air path
• Glow system
• Diesel particulate filter
• AdBlue® system
• Crankcase ventilation system
• Cooling system
• All other emissions-relevant components

Function sequence for the European On-Board Diagnosis (EOBD) 

The EOBD is described in the following steps:

• Function sequence for fault detection 
• Function sequence for test procedure 
• Function sequence for cyclic monitoring 
• Function sequence for continuous monitoring 
• Function sequence for Readiness Code 
• Function sequence for error saving 
• Function sequence for avoiding consequential faults 
• Function sequence for saving the fault freeze frame data 
• Function sequence for fault message 
• Function sequence for reading out the fault memory 
• Function sequence for fault clearing 

Function sequence for fault detection 

The CDI control unit checks itself and its input and output signals for plausibility and detects possible malfunctions.

The faults and their storage are differentiated between as follows:

• The fault is always there
• Loose contact which occurs during a drive.

The following faults are recognized according to their frequency and duration:

• Signals above or below the limit value (for example, short circuit, open circuit, defective sensor)
• An illogical combination of various signals
• Closed-loop control circuit at lower or upper limit of the regulation interval
• Malfunctions in function chains (faulty test processes, e.g. for the smooth running control)
• Fault messages via the CAN buses

Function sequence for test procedure 

A differentiation is made during the test procedure between component testing and function chain testing.

Assembly part checking 

The component checking is direct checking of a assembly part. It includes:

• Monitoring the power supply and electric circuit
• Comparison of sensor signals with other sensor signals and stored comparative values

The following three test results can occur:

• Signal present (checking passed)
• Signal not present (a fault)
• Signal present, but implausible (a fault)

Function chain test 

The function chain test is indirect checking of the effect of controlled change. Here individual assembly parts and systems are checked which cannot be checked over a component checking. The function chain is a controlled procedure of cause and effect.

The CDI control unit controls one or more assembly parts (cause) and evaluates the resulting sensor signals (effect). In the process the CDI control unit compares the sensor signals with stored comparative values and thus recognizes trouble-free or not trouble-free functioning of assembly parts and systems.

Function sequence for Readiness Code 

In order to obtain a statement about freedom from faults of cyclically monitored components and systems during read out of the fault memory, there must be test readiness for this.

The test readiness of an assembly parts or a system is shown using the readiness code. The readiness code allows recognition of whether checks for malfunction detection have run at least once and therefore the assembly parts or the system is active.

The readiness is determined at least once per driving cycle and the readiness code is set for a given readiness. To set the readiness code it is sufficient if the vehicle has checked all components associated with the system at least once.

The test result for setting the readiness code is not important. This means that it will also be set if a fault is found in the systems or the component.

The readiness code is set for the following components and systems once they have been tested:

• Fuel system
• Exhaust gas recirculation
• Smooth running control
• Oxygen sensor
• Oxygen sensor heater
• Regeneration

  If the test readiness of individual systems or assembly parts is not given then these can be created using the diagnostic unit. To do this the function chain sequence is started manually over a menu item of the software.

All readiness codes are reset automatically when deleting DTCs.

Function sequence for error saving 

Emissions-relevant malfunctions just found from the current and previous driving cycle are temporarily stored in the EOBD until confirmed (through occurrence in two consecutive driving cycles) in the form of a fault code, also called a diagnostic trouble code or DTC. If a found malfunction occurs in two consecutive driving cycles, the fault code is stored in the CDI control unit fault memory after the second driving cycle is completed.

Driving cycle

A driving cycle consists of the engine start, vehicle trip and engine shutoff, whereby the coolant temperature must increase by at least 22 ° C to at least 70 ° C when driving.

Function sequence for avoiding consequential faults 

If a faulty signal is recognized and stored all tests are broken off for which this signal is need as a comparative value (so-called transverse locking). Saving of consequential faults is thereby prevented.

Function sequence for saving the fault freeze frame data 

Besides the malfunctions, the operating conditions under which they occurred are also stored as so-called fault freeze frame data.

If the fault occurs a second time then also these fault freeze frame data are stored. If the fault continues to occur then the last stored fault freeze frame data is updated. The fault freeze frame data can be read out for the first and last occurrence of a fault.

Fault freeze frame data are, for example:

• Vehicle speed
• Engine speed
• Coolant temperature
• Intake air temperature
• Charge air temperature and boost pressure
• Supply voltage
• Engine throttle condition
• Adaptation value for injection regulation

Function sequence for fault message 

The engine diagnosis indicator lamp on the instrument panel is actuated by the CDI control unit. If a fault occurs in two driving cycles, one after the other, the indicator lamp engine diagnosis lights up. In the case of catalytic converter damage caused by ignition misfires the engine diagnosis indicator lamp flashes for as long as the ignition misfires occur and then lights up permanently during the whole (remaining) driving cycle.

Fault message over the engine diagnosis indicator lamp ceases automatically after three consecutive trouble-free driving cycles.

Function sequence for reading out the fault memory 

The CDI control unit is connected to the diagnostic connector. Stored DTCs and their fault freeze frame data as well as the readiness codes can be read out using a commercially available diagnostic equipment or XD for "ignition ON" or for a running engine over the diagnostic connector.

Function sequence for fault clearing 

Stored faults are first deleted automatically after 40 successive trouble-free driving cycle from the fault memory. They can, however, also be cleared (after repair work has been done) using commercially available diagnostic equipment or Xentry Diagnostics.

Electrical function schematic for electrical European On-board Diagnosis	PE07.10-D-2725-97TSA
Overview of system components for common rail diesel injection (CDI)	GF07.16-D-9997TSA