Diagnostic connector
A – contact connected to ground;
B – diagnostic contact for sending a signal to the ECU;
G – contact for electric fuel pump control;
M – contact for issuing information (serial data channel)
Code 12 issued by the control lamp "CHECK ENGINE"
The diagnostic connector is used to communicate with the ECU. It is located under the glove compartment on the right side next to the ECU.
The fault codes stored in the ECU memory can be read either by a special diagnostic tool or by counting the number of lamp flashes "CHECK ENGINE". To read codes with the lamp, it is necessary to connect contact "B" (see fig. Diagnostic connector) diagnostic pads with ground. The easiest way to short it to ground is to connect it to contact "A", which is connected to the engine ground.
When contacts "A" and "B" are connected to each other, the key in the ignition switch should be turned to position III (Ignition), but the engine should not run. Under these conditions, the lamp "CHECK ENGINE" should flash code 12 three times in a row. This should happen in the following order: flash, pause (1–2 sec), flash, flash – long pause (2–3 sec), and so on two more times (see Fig. Code 12 output by the control lamp "CHECK ENGINE").
Code 12 indicates that the ECU diagnostic system is working. If code 12 is not displayed, then there are problems with the diagnostic system itself.
After the code 12 is displayed, the lamp "CHECK ENGINE" three times displays fault codes if they exist, or simply continues to display code 12 if there are no fault codes.
If more than one fault code is stored in the ECU memory, they are displayed 3 times each.
Attention! After diagnostics are completed, it is permitted to open contacts "A" and "B" of the diagnostic connector 10 seconds after the ignition is turned off.
Erasing codes
Codes are erased from the ECU memory either after repairs are completed or in order to see if the fault occurs again. To erase, it is necessary to disconnect the ECU power supply for at least 10 seconds.
The power supply can be disconnected either by disconnecting the wire from the negative terminal of the battery or by removing the ECU protection fuse from the fuse box.
Attention! To avoid damaging the ECU, turn its power off and on only when the ignition is off.