This article describes the solution to the 311B EXCAVATOR 2LS fault code
Situation where this code is generated:
The PL522 or 523 module tracks machine hours for reporting to the office. The alternator R-terminal signal is used to detect when the machine is operating. If the input continuously receives a voltage signal above the normal range, machine operation will not be detected. The reported service meter hours (SMU) will also be inaccurate.
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TEST STEPS 1. Check if the R-terminal cable is shorted to the battery. A. Disconnect the PL522 or 523 cable (P1) from the PL522 or 523 module.
B. Measure the resistance of the alternator R-terminal input J1-4 (403MC9-GN-18) to the battery (J1-1). Expected Results: The resistance should be greater than 5000 ohms.
Results:
• OK - The PL522 or 523 harness appears normal. Go to Test Step 2. • Not OK - The PL522 or 523 cable may be shorted to the battery. Repair: Repair the cable and verify that the problem has been corrected.
Stop
Test Step 2. Check the PL522 and 523 harnesses for shorts to the voltage source.
A. Disconnect the PL522 or 523 cable (P1) from the PL522 or 523 module.
B. Start the engine.
C. Measure the alternator R-terminal input (J1-4) to verify that there is a square wave of 11 VDC to 32 VDC. The measurement result should be in the range of 5Hz to 2 kHz, or a stable DC voltage equivalent to the battery voltage is present.
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Expected Result: No stable DC voltage equivalent to the battery voltage is measured when measuring the alternator R-terminal input.
Result: • OK - The signal is a square wave of 11 VDC to 32 VDC. The measurement result should be in the range of 0Hz to 2 kHz , or a steady DC voltage equal to the battery voltage is present. The PL522 or 523 harness may not be faulty.
Go to Test Step 3.
• Not OK - The PL522 or 523 cable may be shorted to a DC power source other than the battery power source. Repair: Repair the cable and verify that the fault has been corrected. Stop Test Step 3. Check the Machine Alternator. A. Disconnect the PL522 or 523 machine cable from the alternator. B. Start the engine. C. Use a multimeter to measure the alternator R-terminals to verify that there is an 11 VDC to 32 VDC square wave. The measurement results should be in the range of 0 kHz to 2 kHz. Expected Results: There should be an 11 VDC to 32 VDC square wave at the alternator R-terminals at 0 kHz to 2 KHz.
Result: • OK - A 0 kHz to 2 KHz 11 VDC to 32 VDC square wave is present at the alternator R-terminals. Go to Test Step 4. • NOT OK - A 0 kHz to 2 KHz 11 VDC to 32 VDC square wave is not present at the alternator R-terminals. Repair: Repair or replace the alternator.
Stop Test Step 4. Check if this diagnostic code is still active. A. Clean all contacts at the harness connectors. B. Reconnect all harness connectors. C. Turn the key start switch to the ON position and operate the machine. D. Use Caterpillar Electronic Technician (Cat ET) to determine if a "CID 1251 FMI 03" diagnostic code is present.
Expected Result: A "CID 1251 FMI 03" diagnostic code is present.
Result: https://127.0.0.1/sisweb/sisweb/techdoc/techdoc_print_page.jsp?returnurl=/sis... Wednesday, October 17, 2018
• Yes - The fault has not been corrected. An ECM fault is unlikely. Repair: Repeat this diagnostic test procedure. If the cause of the diagnostic code is not found, replace the Product Link ECM. Before replacing the PL522 or 523, contact your Caterpillar Technical Communicator. Refer to System Operation, Troubleshooting, Testing and Adjusting, "Electronic Control Module (ECM) - Replace". Stop
• No - No diagnostic code exists. The fault does not exist at this time. The original fault may have been caused by a poor electrical connection or short in a harness connector that was disconnected and reconnected. Resume normal machine operation. Stop
