D6N Track-Type Tractor Caterpillar

Illustration 1	g01766513
Thumb rocker position sensor connections

Illustration 2	g01930757
Location of the blade control handle

This diagnostic code is associated with the thumb rocker position sensor.

This diagnostic code is recorded when the Electronic Control Module (ECM) reads the Pulse Width Modulated (PWM) duty cycle of the thumb rocker position sensor as being out of range.

The possible causes of this condition are listed:

• The signal circuit is shorted to the +battery circuit or shorted to ground intermittently.

• The signal circuit is open intermittently or the sensor is disconnected.

• The sensor may have failed.

• The ECM may have failed. An ECM failure is unlikely.

Note: This diagnostic code is caused by an intermittent condition. The diagnostic code may be active for a while, then the diagnostic code may clear.

Note: This procedure can cause new diagnostic codes to be recorded. Ignore these created diagnostic codes. When the procedure is completed, clear the created diagnostic codes.

Test Step 1. CHECK FOR POWER AT THE SENSOR

1. Do not disconnect the 12 contact machine harness connector from the sensor.

2. At the back of the harness connector for the sensor, insert 7X-1710 Multimeter Probes along voltage supply contact "1" (wire 709-OR) and contact "2" (wire J765-BU).

3. Turn the key start switch and the disconnect switch to the ON position and measure the voltage.

4. Remove the multimeter probe from contact "2" (wire J765-BU) and measure the voltage from contact "1" (wire 709-OR) to frame ground.

Expected Result:

Both voltage measurements are approximately 10 VDC.

Results:

• OK - Both voltage measurements are approximately 10 VDC. Proceed to Test Step 2.

• NOT OK - One or both voltage measurements is not approximately 10 VDC. There is a problem in the circuit.

  Repair: If both of the measurements are not approximately 10 V, check the implement drive train fuse for an open. If the fuse is OK, the voltage supply wire 709-OR is open in the machine harness. Repair the machine harness or replace the machine harness.If the voltage check from contact "1" (wire 709-OR) to frame ground measures approximately 10 VDC and the contact "1" to contact "2" voltage check does not, the return circuit J765-BU is open in the machine harness. Repair the machine harness or replace the machine harness.

  STOP

Test Step 2. CHECK THE SIGNAL CIRCUIT OF THE SENSOR

1. Turn the key start switch and the disconnect switch to the OFF position.

2. At the back of the harness connector for the sensor, insert the 7X-1710 Multimeter Probes along the ground contact "2" (wire J765-BU) and the signal contact "3" (wire K757-YL).

3. Turn the disconnect switch and the key start switch to the ON position.

4. Monitor the signal of the sensor with the 146-4080 Digital Multimeter .

5. With the thumb rocker in the center position, record the duty cycle percentage value. Slowly depress the left-hand side of the thumb rocker and slowly depress the right-hand side of the thumb rocker. Record the high and the low duty cycle values.

Expected Result:

With the handle in the center position, the duty cycle should be approximately 50 percent. The high value should be approximately 80 ± 10 percent and the low value should be approximately 20 ± 10 percent. The values should have increased or decreased at a steady rate through the duty cycle range as the handle is moved forward or rearward.

Results:

• OK - The duty cycle values are in the correct range and the increment and the decrement of the signal is stable. The operation of the position sensor is correct. Proceed to Test Step 3.

• NOT OK - The duty cycle values are not in the correct range or the increment and the decrement of the duty cycle is not stable.

  Repair: The sensor signal is not correct. Replace the blade control handle. Verify that the new handle corrected the problem.

  STOP

Test Step 3. CHECK THE SIGNAL CIRCUIT AT THE ECM

1. Turn the key start switch and the disconnect switch to the OFF position.

2. Insert the 7X-1710 Multimeter Probes into the back of the ECM connectors along "J2-40" (wire K757-YL) and "J1-56" (wire J765-BU).

3. Turn the disconnect switch and the key start switch to the ON position.

4. Monitor the signal of the sensor with a 146-4080 Digital Multimeter .

5. With the thumb rocker in the center position, record the duty cycle percentage value. Slowly depress the left-hand side of the thumb rocker and slowly depress the right-hand side of the thumb rocker. Record the high and the low duty cycle values.

Expected Result:

With the handle in the center position, the duty cycle should be approximately 50 percent. The high value should be approximately 80 ± 10 percent and the low value should be approximately 20 ± 10 percent. The values should have increased or decreased in a steady manner through the duty cycle range as the handle is moved forward or rearward.

Results:

• OK - The sensor signal is the same as measured at the sensor. The machine harness is OK. Proceed to Test Step 4.

• NOT OK - The sensor signal is not the same as the signal at the sensor connector. The signal circuit is open or has a bad connection in the machine harness.

  Repair: There is an open or a bad connection in the signal circuit or in the return circuit. Refer to the complete machine Electrical Schematic. Check all harness connectors that are in the position sensor circuit for corroded, loose, or broken contacts. Repair the machine harness or replace the machine harness.

  STOP

Test Step 4. CHECK THE SIGNAL CIRCUIT FOR A SHORT IN THE HARNESS

1. The key start switch and the disconnect switch remain in the OFF position.

2. Disconnect the machine harness connectors from the sensor and the ECM.

3. Measure the resistance between contact "J2-40" (wire K757-YL) to all contacts that are used in the machine harness connectors for the ECM.

Expected Result:

The resistance of each measurement is greater than 5000 ohms.

Results:

• OK - The resistance is greater than 5000 ohms. The circuit is correct. Proceed to Test Step 5.

• NOT OK - One or more of the resistance measurements is less than 5000 ohms. The signal circuit is shorted to another circuit in the harness.

  Repair: There is a short in the machine harness between wire K757-YL and the circuit with the low resistance measurement. Repair the machine harness or replace the machine harness.

  STOP

Test Step 5. CHECK THE STATUS OF THE DIAGNOSTIC CODE

1. Inspect the harness connectors and clean the contacts of the machine harness connectors.

2. Reconnect all harness connectors.

3. Turn the disconnect switch and the key start switch to the ON position.

4. Clear all inactive diagnostic codes.

5. Operate the machine.

6. Check the status of the CID 1870 FMI 08 diagnostic code.

Expected Result:

The CID 1870 FMI 08 diagnostic code is not active.

Results:

• OK - The CID 1870 FMI 08 diagnostic code is not active. The diagnostic code does not exist at this time. The initial diagnostic code was probably caused by a poor connection or a short at one of the connectors that was disconnected and reconnected. Resume normal operation.STOP

• NOT OK - The CID 1870 FMI 08 diagnostic code is active. The diagnostic code has not been corrected. The ECM may have failed.

  Repair: Check the sensor circuit again. Use the Caterpillar Electronic Technician (Cat ET) service tool in order to perform a wiggle test on the machine wiring harness. The wiggle test can detect intermittent shorts or opens in the machine wiring harness.Perform these tests again. If the cause of the problem is not found, the ECM may have failed. Prior to replacing an ECM, always contact the technical communicator at your dealership for possible consultation with Caterpillar. This consultation may greatly reduce repair time. If the cause of the diagnostic code is not found and the ECM must be replaced, refer to the Troubleshooting, "Electronic Control Module (ECM) - Replace" Section of this manual for details.

  STOP