RING-BACKUP 1404828 - Caterpillar

System Operation Description:The Electronic Control Module (ECM) provides the Engine Speed/Timing Sensor with a supply voltage of 13 1.0 VDC. The Engine Speed/Timing Sensor provides a pulse signal to the ECM. The signal is created as the timing reference gear rotates past the pickup of the Engine Speed/Timing Sensor. The timing reference gear is mounted on the rear of the left camshaft. A unique tooth pattern on the timing reference gear allows the ECM to determine the crankshaft position, engine rotation, and engine rpm.If the Primary Engine Speed/Timing Sensor fails, the ECM will use the Secondary Engine Speed/Timing Sensor until electrical power is removed from the ECM. To prevent any unnecessary down time, the Primary Engine Speed/Timing Sensor should be repaired or replaced at the earliest possible convenience.The Engine Speed/Timing Sensor generates a pulse signal to the Electronic Control Module (ECM) as each tooth passes the sensor. The ECM counts the pulses in order to determine the engine rpm. The ECM memorizes the pattern of the pulses. The ECM compares that pattern to a standard pattern that is stored in memory in order to determine the crankshaft position. The ECM uses this information to determine the No. 1 cylinder. The ECM then triggers each fuel injector to fire in the correct firing order and at the correct time. The actual timing and duration of each injection is determined by the ECM. The ECM uses engine rpm and engine load to determine the timing and duration of injection. The loss of the primary timing signal from the Engine Speed/Timing Sensor generates an alert on the status screen of the Caterpillar Electronic Technician (ET). The loss of the secondary timing signal from the Engine Speed/Timing Sensor triggers the termination of the signals to the fuel injectors.Note: If the ring gear is reversed, the diagnostic codes 190-08 and 342-08 will be generated and the ECM will not fire the injectors.
Illustration 1 g00820920
Test Step 1. Check for "ACTIVE" Diagnostic Codes.
Start the Cat ET.
Turn the engine control to the ON position.
Monitor the active diagnostic codes on the Cat ET.Expected Result:Any of the following diagnostic codes are active:
CID-FMI 190-02 Loss of Engine Speed signal
CID-FMI 190-03 Engine Speed open/short to +batt
CID-FMI 190-07 Primary Speed Sensor misinstalled
CID-FMI 342-02 Loss of Secondary Engine Speed signal
CID-FMI 342-07 Secondary Speed Sensor misinstalled
CID-FMI 342-03 Secondary Engine Speed open/short to +battResults:
OK - Either a CID-FMI 190-03 Engine Speed open/short to +batt diagnostic code or a CID-FMI 342-03 Secondary Engine Speed open/short to +batt diagnostic code is active. Proceed to test step 2.
OK - A CID-FMI 190-07 Primary Speed Sensor misinstalled diagnostic code or a CID-FMI 342-07 Secondary Speed Sensor misinstalled diagnostic code is active.Repair: Switch the Primary Engine Speed/Timing Sensor and the Secondary Engine Speed/Timing Sensor. Verify that the problem is no longer present.STOP
OK - A CID-FMI 190-02 Loss of Engine Speed signal diagnostic code or a CID-FMI 342-02 Loss of Secondary Engine Speed signal diagnostic code is present. Proceed to test step 5.Test Step 2. Check the Electrical Connectors and