816K Landfill Compactor and 815K Soil Compactor Systems Caterpillar

Speed Sensor - Test

Usage:

816K LT6

Transmission ECM

The following is a list of Diagnostic Trouble Codes (DTCs) that are associated with the speed sensor circuits of the machine.

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Table 1
Transmission ECM (MID 81)
DTC	Code Description	System Response
585-8	Transmission Output Speed Sensor 1: Abnormal frequency, pulse width, or period	Transmission shifting may be harsh. The transmission control may be unable to determine the direction of travel. The transmission control will be unable to determine the ground speed of the machine.
672-8	Torque Converter Output Speed Sensor: Abnormal frequency, pulse width, or period	Transmission shifting may be harsh. The transmission control may be unable to determine the direction of travel. The transmission control will be unable to determine the ground speed of the machine.
673-8	Transmission Output Speed Sensor #2: Abnormal frequency, pulse width, or period	Transmission shifting may be harsh. The transmission control may be unable to determine the direction of travel. The transmission control will be unable to determine the ground speed of the machine.

Possible causes for an FMI 8 diagnostic code are:

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

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Illustration 1	g03842013
Schematic of the Speed Sensors

Note: The diagram above is a simplified schematic of the Transmission ECM and the Speed Sensor connections. The schematic is electrically correct. However, not all of the possible harness connectors are shown. Refer to the latest revision for the complete schematic.

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. Identify Active FMI Code Associated With Sensor Circuit	Code present.	FMI 8 diagnostic code, proceed to Test Step 2.
Begin Process For FMI 8 Troubleshooting HERE
2. Check for Machine Movement A. Perform normal operations to move the machine.	The machine moves.	OK - The machine moves. Proceed to Test Step 3. NOT OK - The machine does not move. Repair: Refer to Troubleshooting , UENR0314, " Symptom Procedures - Transmission " for troubleshooting loss of machine movement. Proceed to Test Step 6.
3. Check The Resistance Of The Sensor A. The disconnect switch and the key start switch remain in the OFF position. B. Disconnect the sensor from the machine harness. Insert a multimeter probe in contact 1 and contact 2 of the sensor. C. Measure the resistance of the sensor.	The resistance is between 800 and 1800 Ω.	OK - The resistance is between 800 and 1800 ohms. Proceed to Test Step 4. NOT OK - The resistance is not between 800 and 1800 Ω. The speed sensor has failed. Repair: Replace the speed sensor. Adjust the speed sensor properly when you install the sensor. Refer to Testing and Adjusting , UENR0314, "Speed Sensor - Adjust " for more information on adjusting the speed sensor. Proceed to Test Step 6.
4. Check For An Open In The Sensor Circuit A. Turn the key switch and the disconnect switch to the OFF position. B. Disconnect the sensor from the ECM. C. Disconnect the J1 and J2 wire harness from the Transmission ECM. D. At the harness connector for the sensor, place a jumper wire between the signal contact and the supply contact. E. At machine harness connector for ECM, measure the resistance from the signal contact the supply contact. F. Gently pull on the wires and move the wires in a circular motion at ECM connector and observe the resistance readings. Repeat the process for the sensor connector.	The resistance is less than 5 Ω at all times during the manipulation of the harness.	OK - The resistance is less than 5 Ω. The signal circuit and the ground circuits of the sensor are not open in the machine harness. Proceed to Test Step 5. NOT OK - Resistance reading for the signal circuit or the return circuit is greater than 5 Ω. Repair: Check the signal circuit or the ground circuit for opens or bad connections. 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 measurement that is greater than 5K Ω would indicate an open in the circuit. Proceed to Test Step 6.
5. Check Signal Circuit For Shorts A. The Sensor and the ECM are disconnected from the harness. B. Disconnect the resistor tied to the signal wire. C. The disconnect switch and the key start switch remain OFF. D. Measure the resistance between the signal wire and all other wires used in the J1 and J2 harness connectors.	Resistance greater than 5K Ω for all readings.	OK - The resistance is greater than 5K Ω. The harness circuit is correct. Proceed to Test Step 6. NOT OK - The resistance less than 5 Ω. Repair: A short exists in the harness between the signal wire and the wire with the low resistance reading. 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 measurement that is greater than 5K Ω would indicate an open in the circuit. Proceed to Test Step 6.
6. Check If The Diagnostic Code Remains A. Inspect the harness connectors and clean the contacts of the harness connectors. B. Reconnect all harness connectors. C. Turn key switch and disconnect switch ON. D. Operate the machine. E. Check if diagnostic code is active.	Diagnostic code is no longer present.	OK - Diagnostic code does not exist at this time. 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 - 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 this component, always contact the Technical Communication at your dealership for possible consultation with Caterpillar. This consultation may greatly effect repair time. Follow the steps in Troubleshooting, "Electronic Control Module (ECM) - Replace" if the ECM needs to be replaced. STOP