GF07.16-P-3201T on-Board Diagnosis (OBD) Common Rail Diesel Injection - Function

GF07.16-P-3201T On-Board Diagnosis (OBD) Common Rail Diesel Injection - Function
- with CODE (494) USA version
- with CODE (498) Japan version

Component Identification:

The on-board diagnosis (OBD) performs the following tasks:
^ Monitoring emission-relevant components and systems during driving
^ Determining and storing malfunctions
^ Displaying malfunctions through the CHECK ENGINE indicator lamp (with code (494) USA version) or the engine diagnosis indicator lamp (A1e58) (with code (498) Japan version)
^ Transferring detected faults in the workshop via the data link connector to STAR DIAGNOSIS or to a standard read-out device

The following systems and functions are electronically monitored:
^ Exhaust gas recirculation (EGR)
^ Smooth running control (cylinders 1 to 6)
^ Fuel system
^ Glow system
^ Intake air path
^ Regeneration of the NOx catalytic converter

Readiness code
This code makes it possible to recognize that test procedures (function chains) relating to fault recognition have been completed. The readiness code detects the following electronic systems:
^ AGR
^ Fuel system
^ Smooth running control

The readiness code is set when 2 driving cycles, including a cold start, have taken place without error.

Warm-up cycle
Systems that are not constantly monitored are checked only when a warm-up cycle is executed.
A warm-up cycle consists of the following sub-cycles:
^ Engine start
^ Temperature increase > 4.5 °C
^ Final temperature > 60 °C
^ Engine switch-off
^ Computer run-on at least 10 s (wait for cooling fan run-on)

Driving cycle
One driving cycle consists of:
^ Engine start
^ 35 s at idle
^ Engine switch-off
^ Processor run-on (wait for cooling fan power down)

The CDI control unit checks its input and output signals for plausibility and recognizes possible faults.

Fault recognition
The following faults and error states are detected:
^ Signals over or below the limit value (e.p. line open circuit, short circuit, defective sensor)
^ Plausibility of signals
^ Function chains with faults
^ Error messages via the Controller Area Network (data bus/CAN bus) (CAN) from the fully integrated transmission control (VGS) control unit (Y3/8n4) for vehicles with transmission 722.9 and from the CDI control unit

Fault storage
The CDI control unit places recognized faults together with freeze frame data in its fault memory. If the fault is not confirmed during the following driving cycle, it is deleted. Emission-relevant faults are always entered, they have a high priority. Following 40 fault-free driving cycles, an exhaust gas relevant fault is deleted from the fault memory.

Consequential faults
If a faulty signal is detected and the corresponding fault code is stored, all the tests in which the signal is required as a comparative parameter, are ended. This ensures that no consequential faults are stored.

Fault freeze frame data and operating conditions
If a fault is detected, the following operating conditions to the fault code are stored as freeze frame data:
^ Vehicle speed
^ Engine speed
^ Coolant temperature
^ Boost air temperature
^ Charge air pressure
^ Engine load status

The CHECK ENGINE indicator lamp (with code (494) USA version) or the engine diagnosis indicator lamp (with code (498) Japan version) is actuated by the CDI control unit when the engine is started. If there is no fault, the relevant indicator lamp goes out. If an exhaust-related fault occurs in two consecutive driving cycles or if the limp-home mode is activated for the second time, the relevant indicator lamp lights up. If there is a fault that could damage the catalytic converters, the relevant CHECK ENGINE indicator lamp will flash.

The relevant indicator lamp is switched off by the CDI control unit after three to four consecutive fault-free driving cycles.

Read out the fault memory
Stored faults can be read out using STAR DIAGNOSIS or a standard reading-out device for "terminal 15 ON" or for "terminal 61 ON" via the data link connector.

Erasing the fault memory
Stored faults can be only be deleted using STAR DIAGNOSIS or a standard reading-out device for "terminal 15 ON".

The fault memory is not erased if the battery (G1) is disconnected.

CDI control unit power-down
After faults are erased, it is necessary to wait until the processor has completed its power-down sequence after circuit 15 is switched off. The processor power-down sequence lasts max. 10 s. If the cooling fan run-on is active, it is necessary to wait for the run-on time to complete.