AccuGrade For Wheel Tractor-Scrapers Caterpillar

The display can show several status messages that may indicate various problems (GPS) with the AccuGrade System.

No GPS Receiver Data

The GPS receiver is not outputting data or the GPS receiver has stopped outputting data for at least 1.5 seconds.

Probable Causes

• A problem with the configuration with the GPS receiver

• A fault with a cable

• A fault with the GPS receiver

Isolating The Problem

1. Verify that the harness between the GPS receiver and the display is undamaged and that the connectors are secure.

2. Turn off the display. Then, turn on the display.

3. Send the application file to the GPS receiver again. Cycle power to the GPS receiver.

No GPS Data

The GPS receivers are not computing the high accuracy position data.

Probable Causes

• A problem from the cable to the GPS receiver

• A problem from the connector to the GPS receiver

• A GPS receiver that is faulty

• A disruption in communication within the GPS receiver

Isolating The Problem

Refer to Testing and Adjusting, "Electrical Connector - Inspect" for Step 1 and Step 2.

1. Ensure that the cables for the receiver are not damaged. Ensure that all connectors are secure with no bent pins and/or broken pins.

2. Ensure that the cables for the right receiver are not damaged. Ensure that all connectors are secure with no bent pins and/or broken pins.

3. Check the "GPS Diagnostics" for the left receiver. Refer to Systems Operation, Testing and Adjusting, "Operational Problems".

4. Exchange the GPS receiver.

Low Accuracy (GPS)

The GPS receiver is generating positions with errors that exceed the current "GPS Error Limit" set in the AccuGrade System.

Probable Causes

• Power was cycled to the GPS receiver

• Poor satellite geometry due to the GPS constellation or from physical obstructions

• Poor radio coverage

• Radio receiving corrections from other base stations

• The machine is a long distance from the base station

• Fault with GPS receiver

• Incorrect "GPS Error Limit" set in the AccuGrade System (consult your supervisor)

• Insufficient satellites

Isolating The Problem

1. Confirm that the power to the GPS receiver is normal and that the connectors are secure.

2. Ensure that the antenna cables are not damaged and that all connectors are secure with no pins that are bent or broken.

   Refer to Testing and Adjusting, "Electrical Connector - Inspect"

3. Check the "GPS Diagnostics" information. Refer to Systems Operation, Troubleshooting, Testing and Adjusting, "Operational Problems" for details on running receiver diagnostics. Verify the antenna values for "Satellites Used", "PDOP" and "GPS error". For accurate GPS positions to be generated you need 5 or more satellites and the "PDOP" less than 7. As the "PDOP" decreases and the number of "L1" and "L2" satellites increase the GPS error will decrease.

4. Ensure that the GPS receiver is not obstructed by buildings, trees, or other objects that would impair the line of sight for the GPS receiver.

5. Verify that the "Integrity" is over 85 percent on the "Radio Data Link" screen. Intermittent corrections can result in increased GPS position error.

6. Confirm that the "GPS Error Limit" is set at the correct value. If the type of work you are performing permits, you can adjust the "GPS Error Limit" to be greater than the current "GPS position error" as seen in the diagnostics.

   Note: Always consult the supervisor before you change the "GPS Error Limit".

V. Low Accuracy (GPS)

The GPS receiver is tracking satellites and sending the position data to the display in an appropriate format, but the receiver is generating an autonomous GPS position solution.

Probable Causes

• Base station GPS receiver configuration, power, or cables

• Base station radio configuration, power, or cables

• Machine GPS receiver configuration

• Machine radio configuration, power, or cables

• Fault with GPS receiver

• Jamming of the radio, this may be caused by close proximity to a powerful transmitter such as a radio, microwave, or a cell phone tower

• Receiving corrections from another base and radio network

Isolating The Problem

1. Unplug your base radio and see if your machine radio will synchronize. If the machine radio does synchronize, there is a duplicate data radio network causing interference.

   1. Change your radio network for all radios on the site.

2. Check the GPS status of any other machines on the site. If these machines also show the "V. Low Accuracy" message, start troubleshooting the base station.

3. Verify that the machine radio has power. Refer to Systems Operation, Troubleshooting and Testing & Adjusting, "Machine Radio" for more information on the data radio diagnostics.

4. Verify that the machine radio is synchronized to your network (orange and green lights illuminated). If the radio is not synchronized, use the "Machine Radio Configuration" menu in order to verify that the network setting of the machine radio is identical to the base radio. If the radio is synchronized, verify that the port settings of the machine radio are identical to the GPS receiver.

5. Verify that the GPS receiver is configured correctly. Review the application file on the CompactFlash data card.

6. If all of the machine components have been checked and verified, troubleshoot the base station.

Old Position

The GPS receiver is sending some data in a valid format but the receiver is not generating a valid position.

Probable Causes

• The GPS receiver is acquiring satellites and not yet computing a valid position

• Fault with receiver

Isolating The Problem

1. Check the GPS diagnostics, refer to Systems Operation, Troubleshooting and Testing & Adjusting, "Operational Problems" for details of running receiver diagnostics.

2. If the "GPS Accuracy Mode" is unknown and there is no other information, there may be an internal communication problem with the GPS receiver. Cycle the power to the receiver and send the application file again.

Invalid GPS Config.

The GPS receiver is sending data to the display, but the data is either in the wrong format or there is a baud rate mismatch between the receiver and the display.

Probable Causes

• GPS receiver port settings have changed

• GPS receiver configuration settings are incorrect

• The coordinate system is missing from the GPS receiver configuration

Isolating The Problem

1. Send the "Site Configuration" file to the receiver again.

2. Check the "Calibration" file in order to ensure that the file is valid.

Check M/C Dimensions

The set of dimensions that has been entered into the display is incomplete.

Probable Causes

• A new machine has been selected and the measurements are incomplete

• A machine settings file that was incorrect has been restored

• The system has been reset to factory defaults

Isolating The Problem

1. Restore the correct machine settings file.

2. Ask the supervisor to enter the correct measurements.

3. Perform a measure up of the machine.

Configuration Failed (Diagnostics Screen)

In the "Diagnostics" screen, a component may show "Configuration Failed" instead of "Connected".

Probable Causes

This may happen when an action is taken such as changing the "network number" of a radio or sending a ".cfg" to a MS9X0 receiver.

Isolating the Problem

1. Perform the action again in order to duplicate the error.

2. Press the "Recheck" soft key in the "Diagnostics" dialog.

3. Perform the action again in order to duplicate the error.

4. If the error still occurs, cycle the power to the machine. Leave the machine off for 20 seconds.

5. Perform the action again in order to duplicate the error.

6. If the condition still exists, contact your Technical Communicator for a possible consultation with Caterpillar.