D3K2, D4K2 and D5K2 Track-Type Tractors Systems Speed Sensor

Speed Sensor - Test

D3K2, D4K2 and D5K2 Track-Type Tractors Systems [UENR5465]

D3K2, D4K2 and D5K2 Track-Type Tractors Systems Switch Circuits - Test

D3K2, D4K2 and D5K2 Track-Type Tractors Systems Hydraulic System

ELECTRICAL AND STARTING SYSTEM

SENSOR GP

D3K2, D4K2 and D5K2 Track-Type Tractors Systems Sensor Signal (Analog, Passive) - Test

D3K2, D4K2 and D5K2 Track-Type Tractors Systems Sensor Signal (PWM) - Test

D3K2, D4K2 and D5K2 Track-Type Tractors Systems Sensor Supply - Test

D3K2, D4K2 and D5K2 Track-Type Tractors Systems Speed Sensor - Test

The following is a list of diagnostic codes that are associated with the Speed Sensors of the machine.

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Table 1
Machine ECM (MID 39)
DTC	Code Description	System Response
2685-2	Left Drive Motor Speed Sensor #1⁽¹⁾ : Erratic, Intermittent, or Incorrect	When the fault is active, the ECM will turn off the straight tracking control. The machine may drift to one direction. The detection of the unexpected motor speed is disabled. An EID 695 event code is active when the lever is out of neutral. The lever is out of neutral due to this diagnostic code. Once the diagnostic code is cleared and the lever is moved to neutral, the active event will be cleared.
2685-8	Left Drive Motor Speed Sensor #1⁽¹⁾ : Abnormal Frequency, Pulse Width, or Period	When the fault is active, the ECM will turn off the straight tracking control. The machine may drift to one direction. The detection of the unexpected motor speed is disabled. An EID 695 event code is active when the lever is out of neutral. The lever is out of neutral due to this diagnostic code. Once the diagnostic code is cleared and the lever is moved to neutral, the active event will be cleared.
2686-2	Left Drive Motor Speed Sensor #2⁽²⁾ : Erratic, Intermittent, or Incorrect	When the fault is active, the ECM will turn off the straight tracking control. The machine may drift to one direction. The detection of the unexpected motor speed is disabled. An EID 695 event code is active when the lever is out of neutral. The lever is out of neutral due to this diagnostic code. Once the diagnostic code is cleared and the lever is moved to neutral, the active event will be cleared.
2686-8	Left Drive Motor Speed Sensor #2⁽²⁾ : Abnormal Frequency, Pulse Width, or Period	When the fault is active, the ECM will turn off the straight tracking control. The machine may drift to one direction. The detection of the unexpected motor speed is disabled. An EID 695 event code is active when the lever is out of neutral. The lever is out of neutral due to this diagnostic code. Once the diagnostic code is cleared and the lever is moved to neutral, the active event will be cleared.
2687-2	Right Drive Motor Speed Sensor #1⁽³⁾ : Erratic, Intermittent, or Incorrect	When the fault is active, the ECM will turn off the straight tracking control. The machine may drift to one direction. The detection of the unexpected motor speed is disabled. An EID 695 event code is active when the lever is out of neutral. The lever is out of neutral due to this diagnostic code. Once the diagnostic code is cleared and the lever is moved to neutral, the active event will be cleared.
2687-8	Right Drive Motor Speed Sensor #1⁽³⁾ : Abnormal Frequency, Pulse Width, or Period	When the fault is active, the ECM will turn off the straight tracking control. The machine may drift to one direction. The detection of the unexpected motor speed is disabled. An EID 695 event code is active when the lever is out of neutral. The lever is out of neutral due to this diagnostic code. Once the diagnostic code is cleared and the lever is moved to neutral, the active event will be cleared.
2688-2	Right Drive Motor Speed Sensor #2⁽⁴⁾ : Erratic, Intermittent, or Incorrect	When the fault is active, the ECM will turn off the straight tracking control. The machine may drift to one direction. The detection of the unexpected motor speed is disabled. An EID 695 event code is active when the lever is out of neutral. The lever is out of neutral due to this diagnostic code. Once the diagnostic code is cleared and the lever is moved to neutral, the active event will be cleared.
2688-8	Right Drive Motor Speed Sensor #2⁽⁴⁾ : Abnormal Frequency, Pulse Width, or Period	When the fault is active, the ECM will turn off the straight tracking control. The machine may drift to one direction. The detection of the unexpected motor speed is disabled. An EID 695 event code is active when the lever is out of neutral. The lever is out of neutral due to this diagnostic code. Once the diagnostic code is cleared and the lever is moved to neutral, the active event will be cleared.

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⁽¹⁾	Schematic Part Name - LFT_TRCK_SPD_SNSR (SIGNAL A)
⁽²⁾	Schematic Part Name - LFT_TRCK_SPD_SNSR (SIGNAL B)
⁽³⁾	Schematic Part Name - RH_TRCK_SPD_SNSR (SIGNAL A)
⁽⁴⁾	Schematic Part Name - RH_TRCK_SPD_SNSR (SIGNAL B)

Possible Causes for an FMI 2 and FMI 8 Diagnostic code are:

There is debris in the sensor.
The energize wire is shorted to the ground circuit while the machine is in operation.
The energize wire is shorted to +battery.
An open circuit exists.
The sensor has failed.
The ECM has failed. This condition is unlikely.

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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Illustration 1	g03723702

Note: The diagram above is 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, UENR4092 for the complete schematic.

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Table 2
Troubleshooting Test Steps	Values	Results
1. Identify Active DTC Code Associated With Sensor Circuit	Code present	FMI 2 diagnostic code, proceed to Test Step 2. FMI 8 diagnostic code, proceed to Test Step 2.
Begin Process For FMI 2 and FMI 8 Troubleshooting HERE
2. Check Supply Voltage to the Sensor. B. Turn the key start switch and the disconnect switch OFF. C. At the back of the sensor, spoon into the supply contact. D. Turn the key start switch and the disconnect switch ON. E. Measure voltage between the supply contact and frame ground. F. Gently pull on the wires and move the wires in a circular motion at ECM connector and observe the voltage readings. Repeat the process for the sensor connector.	Voltage is 5V ± 0.5V.	OK - The voltage measure is correct. Proceed to Test Step 4. NOT OK - The voltage measurement is not correct. Repair: proceed to test step 3.
3. Check the Ground Source at the Sensor A. Turn key start switch and disconnect switch OFF. B. At the machine harness connector for the sensor, measure resistance between the ground contact and frame ground.	Resistance is less than 5 Ω	OK - Resistance is less than 5 Ω. Repair - Refer to the diagnostic code procedure in this manual for troubleshooting of the power supply. After the power supply procedure is performed, verify the status of the sensor diagnostic code before proceeding. STOP NOT OK- The resistance is greater than 5K Ω. Repair - The ground source has failed. Repair or replace the machine harness for the ground. STOP
4. Check For An Open In The Sensor Circuit Turn the keyswitch 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 Machine 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 to 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. STOP
5. Check Signal Circuit For Shorts A. The Sensor and the ECM are disconnected from the harness. B. 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. STOP
6. Check the Sensor A. The Sensor and the ECM are disconnected from the harness. B. The disconnect switch and the key start switch remain OFF. C. Replace the sensor with a known good sensor. D. Turn the keyswitch and the disconnect switch ON. E. Observe the status of the diagnostic code.	The diagnostic code moves from active to logged.	OK - The diagnostic code moves from active to logged. Repair: The sensor was the cause of the problem. Leave the new sensor in or replace the faulty sensor. STOP NOT OK- The diagnostic code remains. Proceed to test step 7.
7. Check If The Diagnostic Code Remains. A. Clear all diagnostic codes. B. Operate the machine. C. Stop machine and engage the parking brake. D. Check if the diagnostic code for the sensor is active.	The code for the sensor is NO longer present.	OK - The diagnostic code does not exist at this time. The initial diagnostic code may have been caused by a poor electrical connection or a short at one of the harness connections. Resume machine operation. STOP NOT OK - The diagnostic trouble code has not been corrected. Repair: Recheck the circuit and perform this procedure again. If the diagnostic code is still active, the Machine ECM may require replacement. Prior to replacing the ECM, always contact the Technical Communicator at your dealership for possible consultation with AVSpare. This consultation may greatly reduce repair time. Follow the procedure in Testing and Adjusting, "ECM - Replace" to replace the ECM. STOP