320D3 and 323D3 Excavators Machine Electronic Control System Caterpillar

Engine Speed Control - Test

Usage:

Machine ECM

The following code is associated with the engine speed dial related to the Machine ECM.

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Table 1
Machine ECM (MID 299)
DTC	Code Description	System Response
586-12	Engine Speed Dial Switch : Bad device or component	Cannot control engine speed.

Possible causes for an FMI 12 Diagnostic code are:

The dial switch has failed.
The engine governor control has failed.
The CAN Data Link between the Switch Panel and the Machine ECM is working intermittently or has failed.
The machine harness to the dial switch or the governor control has failed.
The ECM has failed. This situation is unlikely.

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Illustration 1	g03860086
Engine Speed (Governor control) schematic

Note: The diagram above is a simplified schematic of the Machine ECM connections. The schematic is electrically correct. However, not all of the possible harness connectors are shown. Refer to the latest revision of Electrical Schematic, M0094859 for 320D3 and M0094901 for 323D3 excavator electrical systems.

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.

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Table 2
Troubleshooting Test Steps	Values	Results
1. Check For An Active Diagnostic Code A. Turn the key start switch to the ON position. B. Use Cat ET to check for all active diagnostic codes. B. Check for DTC 586-12. C. Check for DTC 246-9 or DTC 246-19.	Diagnostic code CID 586 FMI 12 is active.	OK - DTC 586-12 is active without either DTC 246-9 or DTC 246-19 being active. Proceed to Test Step 2. NOT OK - Diagnostic code DTC 586-12 AND DTC 246-9 or DTC 246-19 are active. Repair: Follow the procedure for troubleshooting the code for the data link circuit. Result: If DTC code 586-12 is no longer active, return the machine to service. If, after troubleshooting the data link, DTC 586-12 is active, proceed to Test Step 2.
2. Inspect The Switch Panel Harness Connection A. Turn the disconnect switch to the OFF position. B. Inspect the harness connector making sure that the connector is clean and tight. C. Check the connector for proper mating. D. Check the connector. Ensure that the wires are secured tightly into the connector. Take care not to pull the wire out of the connector. E. Check any exposed wires at the connector for nicks or signs of abrasion. F. Check for moisture inside the connector. G. Check the connector for dirty contacts or corroded contacts. H. Check each pin and each socket of the switch panel harness connectors. Ensure that the contacts are properly installed. The contacts should mate correctly when the two pieces of the connector are placed together.	The machine harness connectors are tight and free of corrosion.	OK - The machine harness connectors are tight and free of corrosion. Proceed to Test Step 3. NOT OK - The machine harness connectors are in need of repair. Repair: Repair or replace the machine harness. Proceed to Test Step 5.
3. Check The Governor Signal Circuit NOTE: Reference the Illustration in this section of the manual for Step 3. A. The disconnect switch and the key start switch remain in the OFF position. B. Disconnect the ECM and the "governor" control from the machine harness. C. Use a 151-6320 Removal Tool to remove the wire M736-BU(Blue)from the connector at the governor. D. Connect wire M736-BU(Blue)to a ground location, using a jumper wire. E. At the Machine ECM harness connector, measure the resistance at Pin Location 24.	The reading is less than 5 Ω.	OK - The resistance is less than 5 Ω. The resistance of the circuit is correct. Proceed to Test Step 4. NOT OK - The resistance is greater than 5K Ω . The resistance of the circuit is not correct. Repair: Replace the machine harness or repair the machine harness. Note: A resistance that is greater than 5 Ω but less than 5K Ω would indicate a loose connection or a corroded connection in the circuit. A check of all connector locations within the circuit is recommended. A resistance measurement that is greater than 5K Ω would indicate an open in the circuit. Proceed to Test Step 4.
4. Check The Signal Circuit For A Short A. The disconnect switch and the key start switch remain in the OFF position. The governor and Machine ECM remain disconnected from the wiring harness. B. Remove the jumper wire that was installed in the previous Test Step. C. Reconnect wire M736-BU(Blue)to the connector at the governor. D. At the harness connector for the Machine ECM, measure the resistance between pin location 24 and all sources of +battery.	Each reading is greater than 5K Ω.	OK - All measurements are greater than 5K Ω. Proceed to Test Step 5. NOT OK - Resistance is less than 5 Ω, a short exists in the signal circuit. Repair: Replace the machine harness or repair the machine harness. Note: A resistance that is greater than 5 Ω but less than 5K Ω would indicate a loose connection or a corroded connection in the circuit. A check of all connector locations within the circuit is recommended. A resistance measurement that is greater than 5K Ω would indicate an open in the circuit. STOP
5. Check If The Diagnostic Code Remains A. Inspect the contacts of the harness connectors and clean the contacts. B. Reconnect all harness connectors. C. Turn the disconnect switch and the key start switch to the ON position. D. Operate the machine. E. Check if diagnostic code is active.	Diagnostic code is no longer present.	OK - The diagnostic code is no longer active. Repair: The initial diagnostic code could have been caused by a poor electrical connection or a short at one of the harness connectors. Resume normal machine operation. STOP NOT OK - The diagnostic code is active. Repair: If the cause of the diagnostic code is not found, the Engine Speed Switch may have failed. Since the switch is integrated into the Switch Panel, the entire switch panel must be replaced. If the code continues to be active, the Machine ECM may have failed. A failure of the Machine ECM is unlikely. Prior to replacing an ECM, always contact the Technical Communicator for your dealership for possible consultation with Caterpillar. This consultation may effect repair time. If the ECM requires replacement, see the Troubleshooting, "ECM - Replace" section of this manual for additional information. STOP