PIN 2W5974 - Caterpillar

System Operation Description:The master Electronic Control Module (ECM) supplies 5.0 0.5 VDC to the sensors for these parameters:
Inlet air temperature
Engine oil temperature
Unfiltered engine oil pressure
Filtered engine oil pressure
HumidityThe master ECM also provides 5.0 0.5 VDC to the "DESIRED SPEED" potentiometer (if equipped). A "+5 Volt Sensor DC Power Supply short to ground" diagnostic code will be activated if both of these conditions occur:
The desired speed signal wire is shorted to ground.
The "DESIRED SPEED" potentiometer is near the maximum desired speed or at the maximum desired speed.Terminals J1-2 and J1-18 are connected together inside the master ECM. A short circuit on one of these terminals will cause a short circuit on the other terminal.A "+5 V sensor supply" diagnostic code is probably caused by a short circuit or an open circuit in a harness. The next likely cause is a sensor problem. The least likely cause is a problem with the master ECM.Logged diagnostic codes provide a historical record. Before you begin this procedure, use the Caterpillar Electronic Technician (ET) to print the logged codes to a file.This troubleshooting procedure may generate additional diagnostic codes. Keep your mind on correcting the cause of the original diagnostic code. Clear the diagnostic codes after the problem is resolved.
Illustration 1 g00992696
Schematic for the 5 V supplyTest Step 1. Inspect the Electrical Connectors and Wiring
Set the engine control to the OFF/RESET mode. Switch the 16 amp circuit breaker OFF.Note: For the following steps, refer to Troubleshooting, "Inspecting Electrical Connectors".
Illustration 2 g00992710
Terminal box for the master ECM (1) J1/P1 connectors for the master ECM (2) J12/P12 connectors for the 5 volt sensors (3) 16 amp circuit breaker (4) J9/P9 connector for the "DESIRED SPEED" potentiometer (if equipped)
Thoroughly inspect each of the following connectors:
Master ECM J1/P1 connectors
J9/P9 and J12/P12 connectors on the terminal box
Check the torque of the Allen head screws for the ECM connectors. The proper torque is 6 1 N m (55 9 lb in).
Illustration 3 g00979496
Harness side of the master ECM P1 connector (P1-2) 5 volt supply (P1-3) Return (P1-11) Signal for the humidity (P1-14) Signal for the inlet manifold air temperature (P1-16) Signal for the desired speed (P1-17) Signal for the engine oil temperature (P1-18) 5 volt supply (P1-24) Signal for the filtered engine oil pressure (P1-26) Signal for the unfiltered engine oil pressure (P1-35) Return
Illustration 4 g00992758
Harness side of the P9 connector (P9-H) 5 volt supply (P9-I) Signal for the desired speed (P9-J) Return for the signal for the desired speed
Illustration 5 g00888444
Harness side of the P12 connector (P12-A) 5 volt supply (P12-C) Return (P12-E) Signal for the unfiltered engine oil pressure (P12-F) Signal for the filtered engine oil pressure (P12-G) Signal for the humidity (P12-H) Signal for the engine oil temperature (P12-K) Signal for the inlet air temperature
Perform a 45 N (10 lb) pull test on each of the wires that are associated with the circuit for the 5 V sensors.
Illustration 6 g00979887
(5) Inlet air temperature sensor (6) Engine coolant temperature sensor
Illustration 7 g00979888
(7) Unfiltered oil pressure sensor (8) Filtered oil pressure