MUFFLER AS 7Y1508 - 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
Description Conditions which Generate this Code System Response
262-3 5 Volt Sensor DC Power Supply short to +batt 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 short to ground The analog sensor supply voltage is below normal for two seconds.
263-3 Digital Sensor Supply short to +batt The digital sensor supply voltage is above normal for two seconds.
263-4 Digital Sensor Supply short to ground The digital sensor supply voltage is below normal for two seconds. System OperationThe Electronic Control Module (ECM) supplies a regulated voltage of 5.0 0.2 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
Turbocharger outlet pressure sensor
Left turbocharger inlet pressure sensor
Right turbocharger inlet 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 g01217211
Typical schematic
Illustration 2 g01212477
Typical 8 V supply
Illustration 3 g01212479
P1 ECM connector
(P1-2) 5 V sensor supply
(P1-3) Sensor return
(P1-4) 8 V sensor supply
(P1-5) Sensor return
(P1-6) Aftercooler temperature sensor
(P1-7) Coolant temperature sensor
(P1-11) Exhaust temperature (left)
(P1-12) Exhaust temperature (right)
(P1-16) Filtered engine oil pressure sensor
(P1-17) Unfiltered engine oil pressure sensor
(P1-24) Filtered fuel pressure
(P1-25) Unfiltered fuel pressure
Illustration 4 g01212480
P2 ECM connector
(P2-36) Turbocharger outlet pressure sensor
(P2-37) Atmospheric sensor
(P2-38) Left turbocharger inlet pressure sensor
(P2-39) Right turbocharger inlet pressure sensor
(P2-46) Crankcase pressure sensor
Illustration 5 g01234146
Location of ECM connectors
Illustration 6 g01094844
Sensor connector
(Pin A) Sensor supply
(Pin B) Sensor return
(Pin C) Signal Test Step 1. Inspect Electrical Connectors and Wiring
Remove electrical power from the ECM.
Thoroughly inspect the J1/P1 ECM connector and the J2/P2 ECM connector. Inspect all of the connectors that are associated with the circuit. Refer to Troubleshooting, "Inspecting Electrical Connectors" for details.
Perform a 45 N (10 lb) pull test on each of the wires in the ECM connectors that are associated with the circuit.
Check the ECM connector (allen head screw) for the proper torque. Refer to Troubleshooting, "Inspecting Electrical Connectors" for details.
Check the harness and wiring for abrasion and