The control unit is mounted in the cabin, to the right of the fuse box. You can carry out simple checks on the drive and connections yourself. A more detailed check and elimination of serious malfunctions is carried out in a car service.
The locks are controlled by reversible solenoids mounted in the door niches.
Lock switches have 2 positions Lock and Unlock. From the switch, the control unit receives a signal to unlock or lock the door. The control unit reverses the polarity of the signal in accordance with the position of the switch, as a result, the outputs of the solenoid coil are connected either to ground or to a 12 V supply.
On some cars, anti-theft devices are built into the door locks.
Examination
1. The fuses and circuit breakers are checked first.
2. When the lock drive is actuated, a click should be heard in any position of the switch.
Driver door lock switch
3. In the LOCK position of the switch, the circuit must be between pins 2 and 4.
4. In the OFF position of the switch, there should be no circuit between the terminals.
5. In the UNLOCK position of the switch, the circuit must be between pins 2 and 3.
Passenger Door Lock Switch
6. In the LOCK position of the switch, the circuit must be between pins 3 and 4.
7. In the OFF position of the switch, there should be no circuit between the terminals.
8. In the UNLOCK position of the switch, the circuit must be between pins 2 and 4.
Rear compartment door lock switch
9. In the LOCK position of the switch, the circuit must be between pins 1 and 6, and between pins 3 and 4.
10. In the UNLOCK position of the switch, the circuit must be between pins 1 and 3, and between pins 4 and 6.
11. There should be a circuit between pins 2 and 5 (backlight circuit).
12. If the switches are OK, then check for an open in the wires connecting the control unit, solenoids and switches. Otherwise, replace the switch.
13. Check the ground connection of the control unit and switches.
14. If only one solenoid fails, check for voltage by removing the door trim. In the Lock position, there should be voltage on one of the wires. After moving the switch to the Unlock position, voltage should be on the opposite wire.
15. If there is voltage, replace the solenoid.
16. Otherwise, check the relay or wire between the control unit and the solenoid. As a rule, this wire breaks when closing and opening the door.