FERRULE 2A3855 - Caterpillar

Chassis ECM
The following is a list of Diagnostic Trouble Codes (DTCs) that are associated with the sensor supply of the machine.
Table 1
Chassis ECM (MID 87)
DTC Code Description System Response
41-3 8V DC Supply: Voltage above normal Sensors supplied with 8V from this ECM will have data flagged as Invalid and diagnostics on those sensors will be disabled. Torque converter oil temperature will show maximum value on gauge.
41-4 8V DC Supply: Voltage below normal Sensors supplied with 8V from this ECM will have data flagged as Invalid and diagnostics on those sensors will be disabled. Torque converter oil temperature will show maximum value on gauge.
262-3 5V Sensor DC Power Supply: Voltage above normal All 5V active sensors are set to their defaults while the code is active and are DSI 18. De-rate transmission control to the default torque limit map.
262-4 5V Sensor DC Power Supply: Voltage below normal All 5V active sensors are set to their defaults while the code is active and are DSI 18. De-rate transmission control to the default torque limit map. Possible causes for an FMI 3 diagnostic code are:
The sensor supply or the ground circuit in the machine harness is open.
The signal circuit in the machine harness is shorted to another circuit
The signal circuit in the machine harness is open or the sensor is disconnected.
The sensor has failed.
The ECM has failed. A failure of the ECM is unlikely.Possible causes for an FMI 4 diagnostic code are:
The signal circuit in the machine harness is shorted to ground.
The sensor has failed.
The ECM has failed. A failure of the ECM is unlikely.
Illustration 1 g03321014
Schematic of the Sensor Supply
Note: The diagram above is a simplified schematic of the Chassis ECM and the Sensor Supply connections. The schematic is electrically correct. However, not all of the possible harness connectors are shown. Refer to the latest revision of Electrical Schematic, UENR1138 for the complete schematic.Diagnostic Trouble Code Procedure
Note: Prior to beginning this procedure, inspect the harness connectors that are involved in this circuit. Poor connections can often be the cause of a problem in an electrical circuit. Verify that all connections in the circuit are clean, secure, and in good condition. If a problem with a connection is found, correct the problem and verify that the diagnostic code is active before performing a troubleshooting procedure.
Table 2
Troubleshooting Test Steps Values Results
1. Identify Active FMI Code Associated With Sensor Circuit Code present FMI 3 diagnostic code, proceed to Test Step 2.
FMI 4 diagnostic code, proceed to Test Step 5.
Begin Process For FMI 3 Troubleshooting HERE
2. Check The Supply Voltage At The Sensor
A. Turn key start switch and disconnect switch ON.
B. Do not disconnect the sensor from the machine harness.
C. Refer to the schematic to determine the voltage source for the suspected faulty sensor.
D. At the back of the contacts for the sensor, insert the multimeter probes along supply contact A and return contact B. Measure the voltage.
The voltage measurement is approximately 8.0 VDC. OK - The voltage reading is correct for the suspected faulty