ENGINE AR-COMPLETE 3871345 - Caterpillar

Illustration 1 g01242599
Schematic of the CAN Data Link This diagnostic code is associated with the Alternator Charging Voltage Sensor. The FMI 12 means that the ECM has determined that the frequency of the signal of the sensor is below the normal range.This diagnostic code is recorded when the Machine ECM does not receive expected information from the switch panel. The possible causes of this diagnostic code are listed below:
The wires for the CAN Data Link to the Machine ECM are open or the wires are shorted.
Open wire from alternator R terminal.
Alternator failure.
The wrong software is installed on an ECM.Note: Check the "R" term voltage at the alternator and all of the ECM contacts with the wire 403-GN. All "R" term voltage checks should match. If one voltage is missing check for an open harness to that ECM, see Test Step 4.Note: The Machine ECM is equipped with LED indicators that serve as a self-diagnostic check. With the key start switch in the ON position, the following can be determined by the ECM indicator lights:
If all of the LED lights are OFF, voltage is not being supplied to the Machine ECM. Check for power to the ECM.
If the yellow LED is Flashing, a communication error exists on the "CAN" data-link circuit.
If the yellow LED is constantly ON, the Machine ECM software may be missing / not loaded.
If the red LED is Flashing, the Machine ECM has failed and may need replacement. Test Step 1. VERIFY THE HARDWARE AND THE SOFTWARE PART NUMBERS.
Verify that the following information is correct:
The part number of the flash software for the Machine ECM
The part number of the Machine ECMNote: Consult your Caterpillar Dealer for the correct part numbers of the flash software.Expected Result:All of the part numbers are correct.Results:
OK - All of the part numbers are correct. Proceed to Test Step 2.
NOT OK - All of the part numbers are not correct. Repair: The installed Machine ECM has the wrong part number or the incorrect flash software is installed. Replace the Machine ECM that is incorrect. Replace the ECM with a module that has the correct part number. Flash the correct software. See Testing and Adjusting, "Electronic Control Module (ECM) - Flash Program" for additional information.STOPTest Step 2. INSPECT THE HARNESS CONNECTIONS.
Turn the disconnect switch to the OFF position.
Inspect all harness connections that are related to the CAN Data Link. Make sure that the connectors are clean and that the connectors are tight.
Check the connectors for proper mating. Ensure that all the seals are present and in place.
Check the harness for signs of damage or abrasion.
Check the wires at the connector. Ensure that the wires are secured tightly into the connector. Take care not to pull the wire out of the connector.
Check the exposed wires at the connectors for nicks or signs of abrasion.
Check for moisture inside the connector.
Check the connectors for dirty contacts or corroded contacts.
Check each pin and each socket of the machine harness connectors. Ensure that the contacts are properly installed. The