BRAKE & DIFFERENTIAL DRIVE GP 1076687 - Caterpillar

Illustration 1 g01228451
Thumb rocker position sensor connectionsNote: The VPAT attachment is not available on the D7R Series II machines.This diagnostic code is associated with the VPAT thumb rocker position sensor. This sensor is installed on machines that have the VPAT blade attachment installed.This diagnostic code is recorded when the ECM reads the 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. This is unlikely.Note: This diagnostic code is usually caused by an intermittent condition. The diagnostic code may be active for a period of time and 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
Do not disconnect the 12 contact machine harness connector from the sensor.
At the back of the harness connector for the sensor, insert 7X-1710 Multimeter Probes along voltage supply contact 1 (wire 176-OR) and contact 2 (wire 202-BK).
Turn the key start switch and the disconnect switch to the ON position and measure the voltage.
Remove the multimeter probe from contact 2 (wire 202-BK) and measure the voltage from contact 1 (wire 176-BR) to frame ground.Expected Result:Both voltage measurements are approximately 24 DCV.Results:
OK - Both voltage measurements are approximately 24 DCV. Proceed to Test Step 2.
NOT OK - One or both voltage measurements is not approximately 24 DCV. There is a problem in the circuit. Repair: If both of the measurements are not approximately 24 volts, check the implement drive train fuse for an open. If the fuse is OK, the voltage supply wire 176-BR is open in the machine harness. Repair the machine harness or replace the machine harness.If the voltage check from contact 1 (wire 176-BR) to frame ground measures +battery voltage and the contact 1 to contact 2 voltage check does not, the return circuit 202-BK is open in the machine harness. Repair the machine harness or replace the machine harness.STOPTest Step 2. CHECK THE SIGNAL CIRCUIT OF THE SENSOR
Turn the key start switch and the disconnect switch to the OFF position.
At the back of the harness connector for the sensor, insert the 7X-1710 Multimeter Probes along the ground contact 2 (wire 202-BK) and the signal contact 3 (wire K757-YL).
Turn the disconnect switch and the key start switch to the ON position.
Monitor the signal of the sensor with the 146-4080 Digital Multimeter .
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