BODY AS 2356257 - Caterpillar

System Operation Description:Use this procedure to troubleshoot the electrical system if a problem is suspected with a sensor supply or if any one of the diagnostic codes in Table 1 is active or easily repeated.
Table 1
Diagnostic Codes Table    
Code and Description    Conditions which Generate this Code    System Response    
262-3 5 Volt Sensor DC Power Supply voltage above normal     The analog sensor supply voltage is above normal for two seconds.     The code is logged.
All sensors are set to default values.    
262-4 5 Volt Sensor DC Power Supply voltage below normal     The analog sensor supply voltage is below normal for two seconds.    
263-3 Digital Sensor Power Supply (8V Or 12V) voltage above normal     The digital sensor supply voltage is above normal for two seconds.    
263-4 Digital Sensor Power Supply (8V Or 12V) voltage below normal     The digital sensor supply voltage is below normal for two seconds.    System OperationThe Electronic Control Module (ECM) supplies a regulated voltage of 5.0 0.5 VDC to the following sensors:
Aftercooler temperature sensor
Atmospheric pressure sensor
Coolant temperature sensor
Crankcase pressure sensor
Filtered engine oil pressure sensor
Filtered fuel pressure sensor
Left turbocharger inlet pressure sensor
Right turbocharger inlet pressure sensor
Turbocharger outlet pressure sensor
Unfiltered engine oil pressure sensor
Unfiltered fuel pressure sensorThe ECM supplies a regulated voltage of 8.0 0.4 VDC to the following sensors:
Left exhaust temperature sensor
Right exhaust temperature sensorThe supply voltage for the sensors is routed from the ECM to terminal A of each sensor connector. The sensor return for the sensors is routed from the ECM to terminal B of each sensor connector. The ECM provides short circuit protection for the internal power supply. A short circuit to the battery will not damage the internal power supply.Note: The sensors are not protected from overvoltage. A short from the supply line to the +Battery may damage the sensors. If the diagnostic code 262-3 or the diagnostic code 263-3 is logged, it is possible that all of the sensors have been damaged. Repair the sensor supply and check for any active sensor diagnostic codes in order to determine if a sensor has failed.
Illustration 1 g01383544
Typical schematic of 5 V supply
Illustration 2 g01383855
Typical schematic of 8 V supply
Illustration 3 g01444508
Location of the ECM connectors (1) J2/P2 ECM connectors (2) J1/P1 ECM connectors
Illustration 4 g01444246
P1 ECM connector (P1-2) 5 V sensor supply (P1-3) Sensor return (P1-4) 8 V supply (P1-5) Digital return (P1-6) Aftercooler temperature sensor (P1-7) Coolant temperature sensor (P1-11) Left exhaust temperature sensor (P1-12) Right exhaust temperature sensor (P1-16) Filtered engine oil pressure sensor (P1-17) Unfiltered engine oil pressure sensor (P1-18) 5 V sensor supply (P1-24) Filtered fuel pressure sensor (P1-25) Unfiltered fuel pressure sensor (P1-35) Sensor return
Illustration 5 g01444247
P2 ECM connector (P2-36) Turbocharger outlet pressure sensor (P2-37) Atmospheric pressure sensor (P2-38) Left turbocharger inlet pressure sensor (P2-39) Right turbocharger inlet pressure sensor (P2-46) Crankcase pressure sensor (P2-54) Digital return (P2-56) 8 V supply
Illustration 6 g01094844
Sensor connector (Pin A) Sensor supply (Pin B) Sensor return (Pin C) SignalTest Step 1. Inspect Electrical Connectors and Wiring
Turn