HOUSING-REGULATOR 1119374 - Caterpillar

System Operation Description:The master Electronic Control Module (ECM) supplies 8.0 0.8 VDC to these sensors:
Sensor for engine coolant pressure (outlet)
Sensor for inlet air pressure
Sensor for atmospheric pressure
The detonation sensors for the left side of the engineThe slave ECM supplies 8.0 0.8 VDC to the detonation sensors for the right side of the engine.Terminals J1-4, J2-56, and J2-57 are connected together inside the master ECM. A short circuit on one of these terminals will cause a short circuit on the other terminals.A "+8 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 an 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 g00993024
Schematic for the 8 V sensors that are powered by the master ECM
Illustration 2 g00993027
Schematic for the 8 volt sensors that are powered by the slave ECMTest 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 3 g00888914
Terminal box for the master ECM (1) J2/P2 connectors for the master ECM (2) J1/P1 connectors for the master ECM (3) J12/P12 connectors for the 8 volt sensors (4) J11/P11 connectors for the detonation sensors on the left side of the engine (5) 16 amp circuit breaker
Illustration 4 g00901701
Terminal box for the slave ECM (6) J4/P4 connectors for the slave ECM (7) J21/P21 connectors for the detonation sensors on the right side of the engine
Thoroughly inspect each of the following connectors:
J1/P1 and J2/P2 connectors for the master ECM
J12/P12 and J11/P11 connectors on the terminal box for the master ECM
J4/P4 connectors for the slave ECM
J21/P21 connectors on the terminal box for the slave ECM
Check the torque of the Allen head screw for the ECM connectors. The proper torque is 6 1 N m (55 9 lb in).
Illustration 5 g00980958
Harness side of the master ECM P1 connector (P1-4) 8 volt supply for the pressure sensors (P1-5) Return for the pressure sensors
Illustration 6 g00980959
Harness side of the master ECM P2 connector (P2-54) Return for the detonation sensors (P2-55) Return for the detonation sensors (P2-56) 8 volt supply for the detonation sensors (P2-57) 8 volt supply for the detonation sensors
Illustration 7 g00888905
Harness side of the P11 connector (P11-A) Return for the detonation sensors (P11-E) Return for the detonation sensors (P11-F) 8 volt supply for the detonation sensors (P1-J) 8 volt supply for the detonation sensors
Illustration 8 g00888904
Harness side of the P12 connector (P12-L) 8 volt supply for the sensors (P12-N) Return
Illustration 9 g00980959
Harness side of the P4 connector for the slave ECM (P4-54) Return for the detonation sensors (P4-55) Return for the detonation sensors