Implementation of a new strategy for ECU diagnostics
Only misfire diagnostics are performed on a permanent basis. Other components that affect exhaust gas toxicity are tested only once per trip (diagnostics are not performed constantly). However, this sequence of checks does not always take place. Checks are performed while driving if certain conditions are met:
- temperature condition;
- speed condition (threshold, stability.);
- time delay after engine start;
- engine operating conditions (intake manifold pressure, speed, throttle opening angle.).
The on-board diagnostic system is an additional means of detecting common faults in electrical circuits. The system's ECU must provide:
- constant light illumination (or flashing light in case of some malfunctions) on-board diagnostics system warning light;
- memorization of faults detected by the on-board diagnostics system.
Impact on diagnostics and repair
To avoid the on-board diagnostics warning light coming on after the vehicle is returned to the customer, special care must be taken when working on the vehicle.
Some defects may only become apparent in motion after programming the correction parameters: checking the quality of the repair is mandatory.
On the other hand, the complexity of the system makes it necessary to find out from the customer the conditions under which the warning light came on. This information will allow for faster diagnostics of faults.
The conditions for the occurrence of a malfunction are recorded in the ECU memory.
Note: Any electrical faults that result in the toxicity threshold being exceeded will cause the on-board diagnostics warning light to come on.
Functional diagnostics taken into account by the on-board diagnostics system:
- diagnostics of misfires that are destructive to the catalytic converter;
- diagnostics of misfires leading to increased toxicity of exhaust gases;
- diagnostics of upper and lower oxygen sensors;
- diagnostics of the catalytic converter.
Note. Diagnostics of misfiring of the mixture is a priority in relation to the search for other malfunctions. Shift ignition failures are monitored almost continuously after the vehicle's driving conditions are met.
Warning! At the end of each test, do not switch off the ignition under any circumstances before reading the result on the diagnostic tool. Switching off the ignition leads to incorrect interpretation of the results and loss of information about the "diagnostics performed".