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| Illustration 1 | g02953619 |
Charging system and ECM system supply components connections | |
The CID 0168 diagnostic code is associated with the machine system voltage that is supplied to the Machine Electronic Control Module (ECM). The FMI 04 means that the ECM has detected that the system voltage is below normal. The Machine ECM activates this diagnostic code when the system voltage is below 18 V.
The possible causes of this diagnostic code are listed below:
- The alternator output is below normal
- The ECM has failed or the operating software is not the latest version. The ECM is unlikely to have failed
Test Step 1. CHECK THE SYSTEM VOLTAGE AT THE ECM
- Turn the disconnect switch and the key start switch to the OFF position.
- At the J1 harness connector for the Machine ECM, use the 7X-1710 Multimeter Probes to measure the supply voltage. Insert the positive probe along the positive power supply circuit wire at contact J1-39 (wire 127-RD). Insert the negative probe along the supply return circuit wire at contact J1-13 (wire 202-BK).
- Start the engine and run the engine at high idle.
- Measure the voltage between connector contact J1-39 and connector contact J1-13.
Expected Result:
The voltage measurement is in the range of 18 V to 32 V.
Results:
- YES - The voltage measurement is in the range of 18.0V to 32 V. The system voltage is correct. There does not appear to be a problem with the alternator or the machine power supply circuits. Proceed to Test Step 2.
- NO - The voltage measurement is greater than 32 V.
Repair: The operation of the alternator is not correct. Refer to Service Manual, SENR 4130 for brushless alternators for further testing and repair procedures for the alternator or change the alternator.
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Test Step 2. CHECK THE STATUS OF THE DIAGNOSTIC CODE
- Turn the disconnect switch and key start switch to the OFF position.
- Reconnect any harness connectors that were disconnected and checked.
- Start the engine and run the engine at high idle.
- Determine if the CID 0168 FMI 04 diagnostic code is active.
Expected Result:
The CID 0168 FMI 04 diagnostic code is not active.
Results:
- YES - The CID 0168 FMI 04 diagnostic code is not active. The diagnostic code does not exist at this time. The initial diagnostic code could have been caused by a momentary condition that reset when the machine was restarted. Resume normal operation.STOP
- NO - The CID 0168 FMI 04 diagnostic code is still active. The diagnostic code has not been corrected.
Repair: If the system voltage is correct and the ECM is still activating this diagnostic code, the ECM could be causing the problem.Ensure that the latest version of software is loaded on the ECM.If the cause of the problem is not found, contact the Technical Communicator for your dealership for possible consultation with Caterpillar. This consultation may greatly reduce repair time. If the ECM requires replacement, refer to Testing and Adjusting, "Electronic Control Module (ECM) - Replace".
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