Starter fault diagnostics (BMW 5 Series E39)

When the starter does not rotate, first of all it is necessary to check whether the voltage required for its operation is supplied to terminal 50 of the traction relay, the value of which should not be lower than 10 volts. If the voltage is less than the specified value, it is necessary to check the wires included in the electrical circuit of the starter according to the electrical diagram. It is possible to check whether the starter works when the full voltage of the battery is supplied as follows:

Without engaging any gear, turn on the ignition.

Using a wire with a cross-section of at least 4 sq. mm, make a jumper between terminals 30 and 50 of the starter, see the electrical diagram.

If the starter engages the pinion perfectly, then the fault lies in the electrical wires that supply voltage to the starter. If the starter does not engage the pinion, it must be checked in the removed state.

Prerequisite for checking: The wire connections must be tightly tightened and must not be oxidized.