Starter fault diagnostics (BMW 3 Series E30)

If the starter does not turn the engine, first check for voltage at terminal 50 of the traction relay (minimum 8 V), sufficient for its operation. If the voltage is lower than this value, check the starter current circuit wires according to the electrical diagram. The operation of the traction relay is checked when full battery voltage is applied as follows.

Shift the gearbox into neutral, then turn on the ignition.

Then, using an auxiliary wire with a cross-section of at least 4 mm², short-circuit terminals 30 and 50 on the starter (see electrical diagram).

If the starter works clearly, the fault is in the wires leading to the starter. If the starter does not work, it should be removed and checked.

Test conditions: reliable wire connection and non-oxidized contacts.