SHAFT-PLANETARY 6P7742 - Caterpillar

System Operation Description:Use this procedure to troubleshoot the electrical system if a problem is suspected with one of the supply circuits 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
41-3 8 Volt DC Supply : Voltage Above Normal The 8 volt power supply is above normal for two seconds. The code is logged.
The alarm output is activated.
The shutdown output is activated.
The engine is shut down.
41-4 8 Volt DC Supply : Voltage Below Normal The 8 volt power supply is below normal for two seconds.
262-3 5 Volt Sensor DC Power Supply : Voltage Above Normal The 5 volt power supply is above normal for two seconds.
262-4 5 Volt Sensor DC Power Supply : Voltage Below Normal The 5 volt power supply is below normal for two seconds. 5 Volt Power SupplyThe Electronic Control Module (ECM) supplies 5.0 0.5 VDC to these sensors:
Engine oil temperature
Filtered engine oil pressure
Inlet air temperature
Throttle valve differential pressure
Unfiltered engine oil pressureThe ECM also provides 5.0 0.5 VDC to the speed control potentiometer (if equipped).The internal circuits for J1-2 (sensor supply) and J1-18 (speed control supply) are wired to the same voltage source inside the ECM. A short circuit on one of these terminals will cause a short circuit on the other terminal. A 262-4 5 Volt Sensor DC Power Supply voltage below normal will be activated if the following conditions occur:
The desired speed signal wire is shorted to ground.
The speed control potentiometer is near the maximum desired speed or at the maximum desired speed.A diagnostic code for the 5 volt power supply is probably caused by a short circuit or by an open circuit in a harness. The next likely cause is a sensor problem. The least likely cause is a problem with the ECM.
Illustration 1 g01771939
Schematic for the 5 volt power supply
8 Volt Power SupplyThe ECM supplies 8.0 0.8 VDC to these sensors:
Engine coolant pressure sensor (outlet)
Intake manifold pressure sensorThe ECM also supplies 8.0 0.8 VDC to the detonation sensors for the left side of the engine.The internal circuits for J1-4, J2-56, and J2-57 are wired to the same voltage source inside the ECM. A short circuit on one of these terminals will cause a short circuit on the other terminals.A diagnostic code for the 8 volt supply is probably caused by a short circuit or by an open circuit in a harness. The next likely cause is a sensor problem. The least likely cause is a problem with an ECM.
Illustration 2 g01772033
Schematic for the detonation sensors that are powered by the 8 volt supply