LOCK 2P8507 - Caterpillar

System Operation Description:This procedure covers the following codes:
Table 1
Diagnostic Trouble Codes for the Engine Speed/Timing Sensors    
J1939 Code    Description    Notes    
190-8     Engine Speed : Abnormal Frequency, Pulse Width, or Period     The Electronic Control Module (ECM) detects the following conditions:
An intermittent loss of signal or a complete loss of signal from the primary speed/timing sensor for 2 seconds
The engine has been running for more than 3 seconds.
Diagnostic trouble code 168-4 is not active.
678 diagnostic trouble codes are not active.
If equipped, the warning light will come on and the diagnostic code will be logged.
The ECM will use the signal from the secondary speed/timing sensor.
The engine will be derated. If the signal from the secondary speed/timing sensor is also lost, the engine will shut down.    
723-8     Engine Speed Sensor #2 : Abnormal Frequency, Pulse Width or Period     The Electronic Control Module (ECM) detects the following conditions:
A loss of signal from the secondary speed/timing sensor for 2 seconds while the signal from the primary speed/timing sensor remained valid
The engine has been running for more than 3 seconds.
Diagnostic trouble code 168-4 is not active.
678 diagnostic trouble codes are not active.
If equipped, the warning lamp will come on and the diagnostic code will be logged.
The loss of signal from the secondary speed/timing sensor will prevent the engine from starting.    
637-11     Engine Timing Sensor : Other Failure Mode     The Electronic Control Module (ECM) detects the following conditions:
The outputs from the primary speed/timing sensor and the secondary speed/timing sensor differ by more than 8 crankshaft degrees.
The engine has been running for more than 5 seconds.
Diagnostic code 190-8 is not active.
678 diagnostic codes are not active.
If equipped, the warning light will come on. This code will not be logged.    Use this procedure when the engine will not start and the electronic service tool indicates a faulty sensor by displaying "Not Detected" against the faulty sensor on the "No Start Parameter" screen.The engine uses two engine speed/timing sensors. The primary speed/timing sensor is located on the left-hand side of the cylinder block close to the flywheel housing. The primary speed/timing sensor generates a signal by detecting the movement of the teeth that are located on the crankshaft timing ring. The signal that is generated by the speed/timing sensor is transmitted to the ECM. The ECM uses the signal from the speed/timing sensor to calculate the position of the crankshaft. The signal is also used to determine the engine speed. The secondary speed/timing sensor is located on the right-hand side of the cylinder block toward the rear of the engine. The secondary speed/timing sensor generates a signal that is related to the camshaft position. The secondary speed/timing sensor detects the movement of the teeth on the timing ring for the camshaft. The signal that is generated by the speed/timing sensor is transmitted to the ECM. The ECM calculates the speed and the rotational position of the engine by using the signal. The secondary speed/timing sensor is