COUPLING 3P5952 - Caterpillar

Use this procedure to troubleshoot the electrical system if a problem is suspected with the sensor that is for the turbocharger turbine inlet temperature. Also, use this procedure if any one of the diagnostic codes in Table 1 is active or easily repeated.
Table 1
CDL Code and Description Conditions which Generate the Code System Response
1491-3 Right Turbo Turbine Inlet Temperature Sensor voltage above normal The ECM detects a duty cycle that is greater than 96 percent for 10 seconds. The code is logged.
If the signal from the other exhaust temperature sensor is OK, the signal from that sensor is used. If the signal from the other exhaust temperature sensor is not OK, a default value of 0 °C (32 °F) is used.
1491-4 Right Turbo Turbine Inlet Temperature Sensor voltage below normal The ECM detects a duty cycle that is less than 4 percent for 10 seconds.
1491-8 Right Turbo Turbine Inlet Temperature Sensor abnormal frequency, pulse width, or period The ECM detects a sensor frequency that is greater than 600 Hz or less than 400 Hz.
1492-3 Left Turbo Turbine Inlet Temperature Sensor voltage above normal The ECM detects a duty cycle that is greater than 96 percent for 10 seconds. The code is logged.
If the signal from the other exhaust temperature sensor is OK, the signal from that sensor is used. If the signal from the other exhaust temperature sensor is not OK, a default value of 0 °C (32 °F) is used.
1492-4 Left Turbo Turbine Inlet Temperature Sensor voltage below normal The ECM detects a duty cycle that is less than 4 percent for 10 seconds.
1492-8 Left Turbo Turbine Inlet Temperature Sensor abnormal frequency, pulse width, or period The ECM detects a sensor frequency that is greater than 600 Hz or less than 400 Hz. System OperationUse this procedure to troubleshoot any suspect problems with the sensor for the left turbocharger turbine inlet temperature or the right turbocharger turbine inlet temperature.The Pulse Width Modulated Sensor (PWM) provides a signal to the ECM. The PWM signal is used to represent certain engine operating conditions. The sensors receive 8.0 0.4 VDC from a regulated power supply.The ECM performs an automatic calibration of these sensors whenever the ECM is powered and the engine has been off for at least 5 seconds.The ECM provides short circuit protection for the internal power supply. A short circuit to the battery will not damage the internal power supply.The following components can cause problems with the power supply:
Electrical connector or wiring
Sensor
ECMThe most likely cause of a problem is a problem with an electrical connector or wiring. The least likely cause is a problem with the ECM.
Illustration 1 g02604056
Schematic of the PWM sensors for the sensor signal circuit if equipped with A4 ECM
Illustration 2 g06323402
Schematic of the PWM sensors for the sensor signal circuit if equipped with A5 ECM
Illustration 3 g02604098
Location of the PWM sensors (top engine view)
(1) Sensor for the right turbocharger turbine inlet temperature
(2) Sensor for the left turbocharger turbine inlet temperature
Illustration 4 g02604176
Location of the connectors that are