Corsa B
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Diagnosis
Using TECH 1 and these Checking Procedures, it is possible to perform rapid diagnosis on the electronically controlled vehicle systems, i.e. quickly and efficiently determine the faulty circuit. In general, the following procedure should be followed:
· Read trouble code
Each electronic system is monitored by its control unit for incorrect performance. If a fault is recognized, the control unit stores a fault code which can be read out using TECH 1.
The control unit can only recognize the status of the various system components from the voltage levels at the control unit terminals. Any malfunction recognized by the control unit is based on the information received from these terminals.
The trouble code tables in the following sections provide the information sensor and the possible causes for each fault code. They also specify the conditions under which each trouble code is set.
To find the faulty circuit or defective component, read off the remedial measure in the "Quick Check F0:DATA LIST" table via the reference column "Remedy in F0:DATA LIST No." The "Remarks" column is intended for the use of workshop personnel.
Note: In newer control units, the trouble codes are stored in non-volatile EEPROM memories, i.e. it is no longer possible to delete trouble codes by disconnecting the wiring harness plug from the control unit or by disconnecting the battery, as was the case for older control units. Trouble codes in newer control units can only be deleted using TECH 1.
· Carry out Actuator Tests
Various vehicle systems provide so-called Actuator Tests for diagnosis.
Using these Actuator Tests, it is possible to subject various system components (e.g. injectors, relays, servo motors) to a function check.
During the Actuator Test, the TECH 1 prescribes various parameters for the control unit. Therefore, after completion of all Actuator Tests for one system, switch the ignition off and on again once. This re-initializes the system and cancels the values prescribed by TECH 1.
Information on the Actuator Test procedure can be found in the relevant system Checking Procedures.
· Check Data List Parameters
Using TECH 1, it is possible to display the various parameters of a vehicle system. These parameters can be used to form an evaluation of the status of the relevant system.
The "Quick Check F0:DATA LIST" table shows the nominal values for each system parameter. These nominal values can be used along with the actual values displayed by TECH 1 for fault analysis of the system.
Procedure: - Observe the actual values displayed by TECH 1 over a period of time (depending on parameter for each); - During observation, determine an average value; - Compare this average value with the prescribed nominal value.
The column "Terminals" indicates the affected terminal for each control unit and, when used together with the system's circuit diagram, enables detailed diagnosis.
If the TECH 1 displays "NOT PRESENT", this indicates that this parameter is not monitored by the system.
· Carry out Control Tests
Various engine systems allow evaluation of the engine performance at increased/decreased idle speeds, or with the idle stepper motor/idle adjuster more or less open.
During each mode, the data list parameters can be displayed and, if desired, stored.
For newer engine systems, it is also possible to check each individual cylinder's mechanics / tightness / compression by selecting the relevant TECH 1 test (F8:ECU CONTROL ).
Information on the Control Test procedure can be found in the relevant system Checking Procedures.
· Snapshot Mode
If the above checks do not reveal a fault although customer complaints have been received, use the TECH 1 snapshot mode for fault diagnosis.
If possible, recreate the circumstances in which the complaint occurred according to the customer. In addition, the TECH 1 snapshot mode should be set to trigger on "ALL TROUBLE CODES" or "INTERMITTENT". The TECH 1 Operating Instructions contain a more detailed description of the use of the snapshot mode.
After eliminating faults and repairing the system, carry out the following test steps to ensure that the system is functioning correctly:
· Switch ignition off and on again (system initialization)
· Delete trouble codes
· Switch ignition off and on again (repeated system initialization)
· Read trouble codes (there should now be no more trouble codes)
· Carry out Actuator Tests (all Actuator Tests must function correctly)
· Check data list parameters (all parameters must lie within the prescribed nominal values)
· Operate vehicle in conditions similar to those in which the customer experienced the complaint (complaints must no longer occur)
· If the control unit indicated a trouble code before repairs, recreate the conditions which lead to setting of the fault to check whether the fault has really been eliminated.
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