Understand Car Programming and Auto Diagnosis

Auto diagnosis or car diagnosis refers to the use of scan tools (many are available for different car models i.e generic and specific), to read fault codes stored in the engine control unit (ECU) BRAINBOX of a car by plugging the scan tool to a 16 pin connector called OBDII, usually found under the pedal at the driver side, or near the gear.

Car ECU reprogramming or car programming secondarily differs

from conventional script writing and program running as in JAVA, VB or PHP.

Primarily it is reading and writing of code from and to the ECU using special programming devices that communicates with the ECU via OBD II link. This codes are stored in eeprom(s) (8 legs ic) or MCU(s) located in the ECU.

 

As an exemption code can also be manually edited in the ECU by de-soldering this eeproms, reading the data with eeproms reader(e.g Xprog), and using hex editor to edit the data, save the edited data and then write the edited data into the eeprom and solder it back into the ECU

WHEN DOES A CAR REQUIRE DIAGNOSIS OR SCANNING?

Most times car owners visit the mechanic on total or almost complete breakdown of their vehicles, by ignoring drivability issues and dashboard lights. But for ignorance this could have been prevented, by simply observing the check engine light on the dashboard. The picture below are symbolic representations of check engine commonly used by different car manufacturers. When the engine is running and the check light is on then the vehicle requires to be checked

Also referred to as MIL “malfunction indicator light”, the check engine light is triggered on the dashboard in response to sensor signals received by the ECU signifying a drivability issue or component malfunction and stores the applied code representing such malfunction in its memory. A dashboard actually called the INSTRUMENT PANEL is the inner part of the car facing the driver

THREE STATES OF CHECK ENGINE LIGHT AND THEIR MEANING

1.       If the engine is running and the check engine light flashes only a while and goes off, this means a momentary malfunction is present.

2.       If it remains on constantly, it is likely a serious problem. Hard failure signals caused by serious problems will cause the “MIL” to stay on permanently while the engine is running. Sometimes clearing the fault code (MIL reset) might turn off the check engine light but often time it persists until the problem which the code is pointing to is resolved.

3.       A constant flashing “MIL” nonstop is a sign of a major problem and requires immediate stop of the engine to prevent hard damage.