HOUSING 3T1502 - Caterpillar

System Operation Description:Use this procedure to troubleshoot the electrical system if a problem is suspected with the engine speed/timing sensors. Use this procedure to troubleshoot the electrical system if any of the diagnostic codes in Table 1 are active or easily repeated.
Table 1
Diagnostic Codes Table    
Code and Description     Conditions which Generate this Code     System Response    
190-2 Engine Speed Sensor : Erratic, Intermittent, or Incorrect     The signal from the engine speed/timing sensor has been lost.
The code is logged only if the engine has been running for three seconds.     The code is logged.
The Electronic Control Module (ECM) will default to the secondary engine speed/timing sensor. If a valid signal is not received from the engine speed/timing sensor the engine will shut down.    
190-3 Engine Speed Sensor : Voltage Above Normal     The supply voltage for the engine speed/timing sensor is above normal.     The code is logged.
The engine will shut down.    
190-7 Engine Speed Sensor : Not Responding Properly     The primary engine speed/timing sensor is connected to the harness connector for the secondary engine speed/timing sensor.     The code is logged.
The engine will shut down.
Check for the correct installation of the sensors.    
190-8 Engine Speed Sensor : Abnormal Frequency, Pulse Width, or Period     The signal from the engine speed/timing sensor has been incorrect for at least five seconds.     The code is logged.
The ECM will default to the secondary engine speed/timing sensor. If a valid signal is not received from the engine speed/timing sensor the engine will shut down.    
342-2 Secondary Engine Speed Sensor : Erratic, Intermittent, or Incorrect     The signal from the engine speed/timing sensor has been lost.
The code is logged only if the engine has been running for three seconds.     The code is logged.
The ECM will default to the secondary engine speed/timing sensor. If a valid signal is not received from the engine speed/timing sensor the engine will shut down.    
342-3 Secondary Engine Speed Sensor : Voltage Above Normal     The supply voltage for the engine speed/timing sensor is above normal.     The code is logged.
The engine will shut down.    
342-7 Secondary Engine Speed Sensor : Not Responding Properly     The primary engine speed/timing sensor is connected to the harness connector for the secondary engine speed/timing sensor.     The code is logged.
The engine will shut down.
Check for the correct installation of the sensors.    
342-8 Secondary Engine Speed Sensor : Abnormal Frequency, Pulse Width, or Period     The signal from the engine speed/timing sensor has been incorrect for at least five seconds.     The code is logged.
The ECM will default to the secondary engine speed/timing sensor. If a valid signal is not received from the engine speed/timing sensor the engine will shut down.    The engine uses two engine speed/timing sensors. The ECM measures the time between the pulses that are created by the sensors as the gears rotate in order to determine rpm.Under normal operation, the secondary engine speed/timing sensor is