GASKET 6L5461 - Caterpillar

This procedure covers the following diagnostic codes:
Table 1
Diagnostic Codes for the Sensor Supply
J1939 Code CDL Code Code Description
(code descriptions may vary) Comments
678-3 41-3 8 Volt DC Supply voltage above normal The ECM detects the following conditions:
The 8 V supply is more than 8.8 V for more than one second.
The ECM has been powered for more than 3 seconds.
Diagnostic code 168-3 is not active.
The ECM will log the diagnostic code.
The engine may be limited to low idle.
678-4 41-4 8 Volt DC Supply voltage below normal The ECM detects the following conditions:
The 8 V supply is less than 7.2 V for more than one second.
The ECM has been powered for more than 3 seconds.
Diagnostic code 168-4 is not active.
The ECM will log the diagnostic code.
The engine may be limited to low idle.
An active diagnostic code may not cause any noticeable effect on engine response unless the voltage drops below 6.5 V.
3509-3 262-3 5 Volt Sensor DC Power Supply voltage above normal The Electronic Control Module (ECM) detects the following conditions:
The 5 V supply for the sensors is greater than 5.16 V for more than one second.
The ECM has been powered for at least 3 seconds.
Diagnostic code 168-3 is not active.
The ECM sets all of the sensors on the 5 V circuit to the default values.
The engine will be derated.
3590-4 262-4 5 Volt Sensor DC Power Supply voltage below normal The ECM detects the following conditions:
The 5 V supply for the sensors is less than 4.84 V for more than one second.
The ECM has been powered for at least 3 seconds.
Diagnostic code 168-4 is not active.
The ECM sets all of the sensors on the 5 V circuit to the default values.
The engine will be derated.
Follow the troubleshooting procedure in order to identify the root cause of the fault. The following background information is related to this procedure:The ECM supplies regulated +5 V to the following sensors:
Intake manifold air pressure sensor
Fuel pressure sensor
Engine oil pressure sensorThe ECM supplies regulated +8 V to the following sensors:
Primary speed/timing sensor
Secondary speed/timing sensorNote: Refer to the Electrical Schematic for the application for information regarding components that are connected to the 5 V and 8 V supplies on the J1/P1 connector.A diagnostic code can be caused by the following conditions:
A short circuit in the harness
A short circuit to a voltage that is higher than 5.16 V
A faulty sensor
A faulty ECM
An open circuit in the harness
Illustration 1 g03682449
5 V supply circuit
Illustration 2 g03682459
8 V supply circuit
Note: Refer to the Electrical Schematic for the application for information regarding components that are connected to the 5 V and 8 V supplies on the J1/P1 connector.
Illustration 3 g03375608
P2 pin locations for the sensor supply circuits
(10) 8 V supply
(38) Intake manifold pressure sensor return
(39) Oil pressure sensor return
(40) Fuel rail pressure sensor return
(46) Intake manifold air pressure sensor 5 V supply
(47) Oil pressure sensor 5 V supply
(48) Fuel rail pressure sensor 5 V supply
Illustration 4 g03374231
Fuel rail pressure sensor
(1) Ground
(2) Signal
(3) 5 V Supply
Illustration 5 g01170310
Typical example of an engine pressure sensor
(1) 5 V Supply
(2) Ground
(3) Signal
Illustration