If the starter fails, you must first check the presence of voltage on terminal 50 of the traction relay. It must be at least 8 V. If the voltage is less than 8 V, check the starter circuit wires according to the electrical diagram. Starter engagement at full battery voltage can be tested in the following order:
Set the transmission to neutral, turn on the ignition.
Auxiliary wire (section not less than 4 mm2) bridge terminals 30 and 50 of the starter.
If at the same time the starter works properly, then the reason lies in the wiring. If the starter does not work, it must be removed and checked.
When checking the connection, the wires must be well fixed and not oxidized.