Checking and replacing ignition sensors (Motronic system) (BMW 5 Series E28)

Some models are equipped with a TDC sensor mounted on the front of the engine. This sensor is designed to work with the BMW test unit and is not related to the Motronic ignition system.

Speed and position sensors

Examination

1. Locate the two electrical connectors for the sensors. The gray connector (A) is for the position sensor, and the black connector (B) is for the speed sensor.

Early models



Late models



2. On each connector on the sensor side, check the resistance between contact 1 with an ohmmeter (yellow wire) and contact 2 (black wire). The resistance should be between 860 and 1060 ohms.

3. Also check the resistance between pin 3 and either pin 1 or 2. The resistance should be approximately 1000 ohms.



4. If the readings are incorrect, replace the sensor.

Replacement

1. Loosen the sensor mounting screw, using a wrench if necessary, and separate the sensor from the sockets. Disconnect the wires from the sensors one by one - make sure that the connectors are not mixed up when installing new sensors. The location for the position sensor is marked B on the clutch housing (gray connector), and under the speed sensor - D (black connector).

Once the sensors are removed from the sockets, it is advisable to check the condition of the protrusion on the flywheel. Manually turn the engine so that the protrusion is visible.

2. Tighten the sensor mounting screw carefully, being careful not to overtighten the screws.

Pulse sensor (late models)

Examination

1. Locate the two electrical connectors of the sensors. Disconnect the connector from the front sensor.





2. Using an ohmmeter, check the resistance between contact 1 on each connector on the sensor side (yellow wire) and contact 2 (black) wire. The resistance should be from 500 to 600 Ohms.

3. If the readings are incorrect, replace the sensor.

Replacement

1. Use a 5 mm Allen key to loosen the impulse sensor mounting bolt. Impulse sensor (shown by arrow) located on the timing belt cover on one side of the pulley (late models). Remove the sensor from the bracket and remove it.



2. When installing a new sensor, use a bronze feeler gauge to maintain the correct distance between the end of the sensor and the rotor. The sensor protrusion should be installed at a distance of 1.0±0.3 mm from the sensor rotor.



3. Tighten the mounting bolt, being careful not to overtighten it.

[The original article is posted on the resource www.bmwman.ru]