WATER PUMP 5P8956 - 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 master Electronic Control Module (ECM) supplies 5.0 0.5 VDC to these sensors:
Engine oil temperature sensor
Intake manifold air temperature sensor
Pressure sensor for unfiltered oil
Pressure sensor for filtered oilThe master 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 master 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