Series 55 – Section 2.15 Synchronous Reference Sensor

Section 2.15
Synchronous Reference Sensor

The Synchronous Reference Sensor (SRS) is an electronic component that is mounted on the back of the flywheel housing. See Figure "SRS Location" .‪

1.SRS Connector‪	3.Bolt‪
2.SRS Sensor‪	4.Flywheel Housing‪

Figure 1. SRS Location

Note: The length of the SRS sensor element is 37.15-38.15 mm (1.463-1.502 in.).

The SRS sends a signal to the ECM. This signal is generated by a raised metal pin on the rear of the flywheel gear. The flywheel pin passes by the SRS as the number one piston reaches approximately 45 ° before top-dead-center. The ECM uses this information to determine engine speed.‪

Section 2.15.1
Repair or Replacement of Synchronous Reference Sensor

The SRS is non-serviceable and should be replaced as a unit. No adjustment or repair is required.‪

Section 2.15.2
Removal of Synchronous Reference Sensor

Remove the SRS as follows:‪

1. Disengage the locking tang on the SRS connector. Grasp the connector bodies and gently pull them apart. See Figure "SRS Location" .
2. Using a socket and long extension, remove the SRS bolt.
3. Remove the SRS by pulling it straight out of the gear case.

Section 2.15.3
Installation of Synchronous Reference Sensor

Install the SRS as follows:‪

1. The SRS is an electronic component. Use care upon installation. The O-ring on the senor may be coated with clean engine oil for ease of installation.
2. Insert the SRS into the flywheel housing and index the hole in the bracket with the hole in the flywheel housing.
3. Insert the SRS bolt and torque it to 20-26 N · m (15-19 lb · ft).
4. Plug the connectors together, ensuring the locking tang clicks into place.
5. Turn the ignition to the "ON" position. If any diagnostic code other than 25 appears, refer to the DDEC Troubleshooting Guide, 6SE477 or 6SE489.