CS54B, CP54B and CS64B Vibratory Soil Compactors Machine Electronic Control System Caterpillar

Speed Sensor - Test

Usage:

Machine ECM

The following is a list of diagnostic codes (SPN) associated with the Speed Sensors of the machine.

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Table 1
Machine ECM (MID 39)
SPN-FMI	Code Description	System Response
6728-8	Vibration Sensor #1: Abnormal frequency, pulse width, or period	When Vibe is operating, Limit Output to: 1350mA (7x models) 1190 mA (54, 64 models) 1240 mA (all other models) Fault Level - 2

Possible causes for an FMI 8 diagnostic code are:

The sensor has failed.
The spacing of the sensor is incorrect.
The signal circuit of the speed sensor is open.
Intermittent connections or poor connections.
Mechanical devices are loose.
Incorrect software is loaded to the ECM.
The ECM has failed. A failure of the ECM is unlikely.

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Illustration 1	g03824325
Speed Sensor connections

The diagram above is a simplified schematic of the Machine ECM connections. The schematic is electrically correct. However, not all the possible harness connectors are shown.

For the full Electrical Schematic of the Soil Compactors in this manual, refer to the Electrical Schematic, UENR6390.

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. For sensors powered via the fuse panel, check the condition of the appropriate fuse before beginning the troubleshooting procedure.

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Table 2
FMI 8 Troubleshooting
Troubleshooting Test Steps	Values	Results
1. Verify The Software Version A. Check and record the latest software version for the machine electronic controls from SIS. B. Verify that the latest version of software has been loaded to the ECM.	The software is current.	OK - All of the software is current. Proceed to Test Step 2. NOT OK - There is a more recent software release that is available. Repair: Flash all controls with the latest software release. Refer to Troubleshooting, "ECM Software - Install". Proceed to Test Step 4.
2. Check The Signal Circuit For An Open A. The key start switch and the disconnect switch remain in the OFF position. B. Disconnect the machine harness connector from the sensor. C. Disconnect the machine harness connectors from the ECM. D. At the harness connector for the sensor, place a jumper wire between the signal contact and the return contact. E. At machine harness connector for ECM, measure the resistance between the signal contact the return contact.	The resistance value is less than 5 Ω.	OK - The resistance value is less than 5 Ω. The harness is correct. Proceed to Test Step 3. NOT OK - The resistance is greater than 5K Ω. There is an open circuit in the signal circuit or the return circuit. Note: A resistance greater than 5 Ω but less than 5KΩ indicates a loose connection or corroded connection in the circuit. A resistance value that is greater than 5K Ω would indicate an open in the circuit. Repair: Repair or replace the machine harness. Proceed to Test Step 4.
3. Check The Signal Circuit For A Short A. The disconnect switch and the key start switch remain OFF. B. The sensor and the ECM remain disconnected from the harness. C. Measure the resistance between the signal contact and all other contacts used in the ECM harness connectors.	The resistance values are greater than 5K Ω.	OK - The resistance values are greater than 5K Ω. The harness circuit is correct. The sensor may have failed. Repair- Replace the speed sensor. Proceed to Test Step 4. NOT OK- A resistance value is less than 5 Ω. Repair: A short exists in the harness between the signal circuit and the circuit with the low resistance value. Repair or replace 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 resistance value that is greater than 5K Ω would indicate an open in the circuit. Proceed to Test Step 4.
4. Check If The Diagnostic Code Remains A. Reconnect all harness connectors. Return machine to normal operating condition. B. Turn the key start switch and the disconnect switch ON. C. Clear all diagnostic codes. D. Operate the machine. E. Stop the machine and engage the safety lock. F. Check if the diagnostic code is active.	The diagnostic code is no longer present.	OK - The diagnostic code does not exist at this time. The initial diagnostic code may have been caused by poor electrical connection or short at one of the harness connections. Resume machine operation. STOP. NOT OK - The diagnostic trouble code has not been corrected. If the diagnostic code has not been corrected after performing the procedure a second time, the ECM may require replacement. Prior to replacing the ECM, always contact the Technical Communicator at your dealership for possible consultation with Caterpillar. This consultation may effect repair time. Follow the steps in Troubleshooting, "ECM - Replace" if the ECM needs to be replaced. STOP.