TOOTH-SCARIF 1957234 - Caterpillar

Use this procedure to troubleshoot a problem with one or more of the engine speed/timing sensors. Also, use this procedure if one of the following diagnostic codes is active or easily repeated.
Table 1
J1939 Code and Description    CDL Code and Description    Comments    
190-8
Engine Speed : Abnormal Frequency, Pulse Width, or Period     190-8
Engine Speed : Abnormal Frequency, Pulse Width, or Period     The Electronic Control Module (ECM) can default to the secondary engine speed/timing sensor. The default will occur if a valid signal is not received from the primary engine speed/timing sensor.
The engine will shut down only if the signals from the primary engine speed/timing sensor and the secondary engine speed/timing sensor are abnormal.
The code is logged.    
723-8
Engine Speed Sensor #2 : Abnormal Frequency, Pulse Width, or Period     342-8
Engine Speed Sensor #2 : Abnormal Frequency, Pulse Width, or Period     If a valid signal is not received from the secondary engine speed/timing sensor, the ECM will default to the primary engine speed/timing sensor.
The engine will shut down only if the signals from the primary engine speed/timing sensor and the secondary engine speed/timing sensor are abnormal.
The code is logged.    
Illustration 1 g03846847
All of the electrical connectors may not be shown. Refer to the electrical schematic.
Table 2
Troubleshooting Test Steps    Values    Results    
1. Check for Codes
A. Connect Cat® Electronic Technician (ET) to the service tool connector.
B. Start the engine.
C. Run the engine until normal operating temperature is reached.
Note: If the engine will not start, monitor the engine rpm on Cat ET while the engine is being cranked. If necessary, power Cat ET from another battery while the engine is being cranked.
D. Determine if a code is active or logged.
   
Codes
   
Result: A -8 code is not active or logged.
Repair: Refer to the appropriate engine symptom in this Troubleshooting manual.
Result: A -8 code is active or logged.
Proceed to Test Step 2.
Result: No engine rpm. Cat ET is not reporting engine rpm for at least one engine speed/timing sensor while the engine is cranked.
Proceed to Test Step 3.
   
2. Check the Installation of the Sensor Assembly
A.