HOSE-AIR 4836972 - Caterpillar

Illustration 1 g02361216
5 VDC Power Supply Connections
This diagnostic code is associated with the 5 VDC power supply for the "Transmission/Chassis ECM". The 5 VDC power supply provides power for the accumulator pressure sensor of the service brake. The return circuit of the power supply is also used by the left joystick.The CID 0262 FMI 03 diagnostic code is active when the ECM detects that the 5 VDC power supply voltage is higher than normal.The following conditions could cause this diagnostic code to be active:
The power supply circuit is shorted to a higher voltage source.
The ECM has failed. A failure of the Chassis ECM is unlikely.Note: Before performing this procedure, inspect the harness connectors that are involved in the circuit. Poor connections can often be the cause of a problem in an electrical circuit. Verify that all connections in the circuit are clean, that all connections are secure and that all connections are in good condition. If a problem with a connection is found, correct the problem and verify that this diagnostic code is active before performing this procedure. Note: The following test procedure may create other diagnostic codes. Ignore these created diagnostic codes and clear the diagnostic codes when the problem has been corrected. Verify the diagnostic code CID 0262 FMI 03 is active before performing this procedure.Test Step 1. CHECK THE VOLTAGE AT THE SENSOR
Turn the disconnect switch and the key start switch to the ON position. Note: Confirm that the CID 0262 FMI 03 diagnostic code is active before proceeding.
Disconnect the connector of the machine harness from the accumulator pressure sensor of the service brake.
At the connector of the machine harness for the sensor, measure the voltage from supply contact A (wire L730-OR(Orange)) to the return contact B (wire L731-BR(Brown)). Expected Result:The voltage measurement is 5.0 0.5 DCV. The diagnostic code CID 0263 FMI 03 is not longer active. The diagnostic code CID 2987 FMI 04 (Brake Charge Pressure Sensor 1) is active.Results:
OK - The voltage measurement is 5.0 0.5 DCV. The voltage is correct. Repair: Replace the sensor. Verify that the new sensor corrected the problem before the machine is operated.STOP
NOT OK - The voltage measurement is greater than 5.0 0.5 DCV. The measurement is not correct. Proceed to Test Step 2.Test Step 2. CHECK THE POWER SUPPLY AT THE ECM
Turn the disconnect switch and the key start switch to the OFF position.
At ECM connector J1, use a 151-6320 Removal Tool to remove the supply wire and the socket at contact J1-11 (wire L730-OR(Orange)) and the return wire and the socket at contact J1-21 (wire L731-BR(Brown)) from the connector. The machine harness connector J1 remains connected to the ECM.
Turn the disconnect switch and the key start switch to the ON position.
Use the machine schematic to locate the first connector away from the ECM. Remove pins J1-11 and J1-21. Spoon into the ECM with the newly disconnected wires. Measure the voltage at the contact of the power supply J1-11 and the return contact