Checking/removing and installing the traction relay (BMW 5 Series E39)

If the traction relay is defective, the starter pinion does not extend to the flywheel ring gear, and the starter cannot turn the engine crankshaft. This defect occurs more often than a defective starter motor.

Checking the installed starter

Prerequisite for checking: the battery is fully charged.

Turn off the gear, put the gear shift lever in neutral position.



Using an auxiliary wire, short-circuit terminals 30 at the starter (thick positive wire) and 50 (thin wire that goes to the ignition switch), the starter pinion should be quickly thrown forward and the starter anchor should rotate. If this does not happen, remove the starter and check it again in the removed state.

Removal

Remove the starter and test it again using an independent battery. A wire for starting the engine from the battery of another car is suitable as a power cable for terminal 50 of the starter. If the starter pinion is thrown forward and the starter anchor does not rotate, repair the starter electric motor in a workshop.

If the starter gear does not eject, remove the traction relay and replace it.

Installation

Seal the connector plane - F- with a suitable sealant.



Connect the traction relay to the drive engagement lever, then screw the traction relay to the starter housing,

Screw the wire to the traction relay.

Check the starter again as described above.

Install the starter.