AccuGrade® - CD700 Grade Control System (GPS/ATS/Laser) Caterpillar

Illustration 1	g01504273

This procedure is associated with the harnesses that connect to the AccuGrade Grade Control System or the internal AccuGrade CAN circuit of an AccuGrade component. System components may be experiencing intermittent communications. This results in lost system data.

Test Step 1. CYCLE THE POWER TO THE SYSTEM.

1. Turn OFF the display.

2. Turn the key start switch for the machine to the OFF position.

3. Turn the key start switch for the machine to the ON position.

4. Turn ON the display.

5. Check the status of the system components on the "Diagnostics" screen.

   Make sure that all the required components are shown as "Connected".

Expected Result:

All system components show as "Connected" in the "Diagnostics" screen.

Results:

• YES - All of the system components are shown as "Connected" in the "Diagnostics" dialog.

  Repair: The issue was caused by the internal CAN circuit of the display. Cycling the power has reset the display. Return the machine to normal operation.

  STOP

• NO - All system components do not show as "Connected" in the "Diagnostics" dialog. Proceed to Test Step 2.

Test Step 2. CHECK THE RESISTANCE OF THE CAN CIRCUIT.

1. Place the key start switch and the disconnect switch in the OFF position.

2. Take the following measurement at the connector for the sensor communicating on AccuGrade CAN network. Measure the resistance between contact C (wire K960-PK) and contact D (wire K961-GN).

Expected Result:

The resistance measurement is 60 ± 6 ohms.

Results:

• YES - The resistance measurement is 60 ± 6 ohms. Proceed to Test Step 4.

• NO - The resistance measurement is NOT 60 ± 6 ohms. Proceed to Test Step 3.

Test Step 3. CHECK THE TERMINATION RESISTOR.

1. Disconnect the 3-pin connector for both of the termination resistors.

2. Measure the resistance between contact A and contact B for one resistor. Measure the resistance between contact A and contact B for the other resistor. Note the resistance.

Expected Result:

The resistance measurements are 120 ± 12 ohms.

Results:

• YES - The resistance measurements are 120 ± 12 ohms. Reconnect the resistors. Proceed to Test Step 4.

• NO - One or both resistance measurements is NOT 120 ± 12 ohms.

  Repair: Replace the termination resistors that did not measure 120 ± 12 ohms.

  STOP

Test Step 4. CHECK THE CAN CIRCUIT FOR SHORT TO GROUND.

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

2. Measure the resistance between contact A (wire K960-PK) and frame ground. Measure the resistance between contact B (wire K961-GN) and frame ground. Note the resistance.

Expected Result:

The resistance measurements are greater than 5000 ohms.

Results:

• YES - The resistance measurements are greater than 5000 ohms. Proceed to Test Step 5.

• NO - One or both resistance measurements are less than 5 ohms.

  Repair: The CAN circuit is shorted to ground. Repair the harness or replace the harness.

  STOP

Test Step 5. CHECK THE CAN CIRCUIT FOR SHORT TO + BATTERY.

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

2. Measure the voltage between contact A (wire K960-PK) and frame ground. Measure the voltage bewteen contact B (wire K961-GN) and frame ground. Note the voltage.

Expected Result:

The voltage measurements are approximately 2.5 VDC.

Results:

• YES - The voltage measurements are approximately 2.5 VDC. Proceed to Test Step 6.

• NO - One or both resistance measurements are greater than 5 volts.

  Repair: The CAN circuit is shorted to "+" battery. Repair the harness or replace the harness.

  STOP

Test Step 6. CHECK THE CAN CIRCUIT FOR FAILED COMPONENTS.

Note: Ensure that the diagnostic for the missing component is active prior to performing this step.

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

2. Turn ON the display.

3. Disconnect the following components from the system one at a time. After each component has been disconnected, check the display in order to verify that the correct components are connected.
   • Angle sensor

   • Electric mast (if equipped)

   • Laser receiver (if equipped)

   • GPS receiver (if equipped)

   • AccuGrade radio (if equipped)

   • Machine ECM (A4:M1)

Expected Result:

Removing one of the system components will cause the "Diagnostic" screen to show all connected components.

Results:

• YES - Removing one of the system components will cause the "Diagnostic" screen to show all connected components.

  Repair: The last component that was removed from the system has failed. Replace the last component that was removed from the circuit.

  STOP

• NO - Removing one of the system components did not cause the "Diagnostic" screen to show all connected components. Proceed to Test Step 7.

Test Step 7. CHECK FOR AN OPEN CAN CIRCUIT.

1. Turn OFF the display.

2. Turn the key start switch for the machine to the OFF position.

3. Turn the disconnect switch for the machine to the OFF position.

4. Disconnect all AccuGrade components from the harness (including the display).

5. Measure the resistance between the CAN high and CAN low circuits from the harness connector for the display to the CAN high and CAN low contacts for all the other AccuGrade components.

Expected Result:

The resistance measurements for each of the CAN circuits (high and low) are less than 5 ohms.

Results:

• YES - The resistance measurements for each of the CAN circuits (high and low) are less than 5 ohms.

  Repair: The display has failed. Replace the display.

  STOP

• NO - The resistance measurements for one or more of the CAN circuits (high and low) are greater than 5000 ohms.

  Repair: The CAN circuit is open in the harness. Repair the harness or replace the harness.

  STOP