AccuGrade For Wheel Tractor-Scrapers Caterpillar

Illustration 1	g01619517
Partial Schematic

The conditions that are listed below may cause the data radio to not power up:

• Display

• Fuse

• Circuit Breaker

• Main Power Relay

• Wiring

• Faulty Radio

Test Step 1. VERIFY THAT THE DISPLAY WILL POWER UP

1. Ensure that the disconnect switch for the battery and the key start switch are in the ON position.

2. Turn on the display.

Expected Result:

The display turns on.

Results:

• YES - The display turns on. Proceed to Test Step 2.

• NO - The display does not turn on.

  Repair: Perform the procedure that is listed in the Troubleshooting, "Electrical Power Supply (Display)" section of this manual.

  STOP

Test Step 2. VERIFY THAT THE DATA RADIO POWERS UP

1. Verify that the power LED on the data radio is illuminated.

Expected Result:

The power LED on the data radio is illuminated.

Results:

• YES - The power LED on the data radio is illuminated.

  Repair: The problem was caused when the display was turned off. Return the machine to service.

  STOP

• NO - The power LED on the data radio is not illuminated. Proceed to Test Step 3.

Test Step 3. CHECK THE POWER TO THE DATA RADIO

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

2. Disconnect the harness connector from the data radio.

3. Measure the voltage between pin "A" and pin "B" on the harness connector for the radio.

Expected Result:

The measured voltage is approximately machine voltage.

Results:

• YES - The measured voltage is approximately machine voltage. The data radio has failed.

  Repair: Replace the data radio. Return the machine to service.

  STOP

• NO - The voltage is not approximately machine voltage. Proceed to Test Step 4.

Test Step 4. CHECK THE FUSE

1. Disconnect the 10 amp "AccuGrade" fuse (Fuse 17) from the fuse panel.

2. Check the resistance across the two contacts of the fuse.

Expected Result:

The resistance measurement is less than 1.0 ohm.

Results:

• YES - The resistance measurement is less than 1.0 ohm. The fuse is not open. Proceed to Test Step 5.

• NO - The resistance measurement is greater than 1.0 ohms. The fuse is open.

  Repair: Replace the fuse. Return the machine to operation.

  STOP

Test Step 5. CHECK THE CIRCUIT BREAKER

An open "Main Breaker" circuit will disrupt power to the display.

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

2. Check for an open at the 80 amp "Main Breaker" circuit breaker.

Expected Result:

The 80 amp "Main Breaker" circuit breaker is open.

Results:

• YES - The circuit breaker is open.

  Repair: Reset the open circuit breaker. Resume the operation of the machine.

  STOP

• NO - The 80 amp "Main Breaker" circuit breaker is not open. Proceed to Test Step 6.

Test Step 6. CHECK THE MAIN POWER RELAY

1. Place the disconnect switch and the key start switch in the ON position. The engine should be off.

2. Measure the voltage between wire (CBL-PU) on the main power relay and frame ground.

Expected Result:

The voltage measurement is between 18 VDC and 32 VDC.

Results:

• YES - The voltage measurement is between 18 VDC and 32 VDC. Proceed to Test Step 7.

• NO - The voltage measurement is not between 18 VDC and 32 VDC.

  Repair: Verify that between 18 VDC and 32 VDC is present at the main power relay on wire (CBL-RD) and wire (308-YL). If voltage is not present on wire (308-YL), repair the wire (308-YL) between the main power relay and the keyswitch. If voltage is not present on wire (CBL-RD), verify that the main breaker is not open. Check the wire (200-BK) for continuity to ground from the main power relay. If the ground is okay and there is between 18 VDC and 32 VDC present on wire (CBL-RD) and wire (308-YL) at the main power relay, replace the main power relay.

  STOP

Test Step 7. CHECK THE POWER SUPPLY CIRCUIT FOR AN OPEN

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

2. Remove the "AccuGrade" fuse from the fuse block. The "AccuGrade" fuse is number "17".

3. Disconnect the harness connector from the data radio.

4. With the "AccuGrade" fuse removed from the fuse block, measure the resistance between the load contact wire (184-BLU) of the fuse block and the harness connector contact "A" wire (184-BLU) for the data radio.

Expected Result:

The resistance measurement is less than 5.0 ohms.

Results:

• YES - The resistance measurement is less than 5.0 ohms. The resistance measurement does not indicate an open or a bad connection in the power circuit of the machine harness. Proceed to Test Step 8.

• NO - The resistance measurement is greater than 5.0 ohms. The resistance measurement indicates an open connection or a bad connection in the power circuit of the machine harness.

  Repair: There is an open connection or a bad connection in the power supply circuit of the machine harness. A resistance measurement that is greater than 5 ohms but less than 5000 ohms could indicate that one of the connection points in the circuit is not an open connection but the connection is not a good connection.Refer to the complete Electrical System Schematic of the machine. Check all of the connectors that are in the power supply circuit. Ensure that all connections are clean, that all connections are secure and that all connections are in good condition. Repair the machine harness or replace the machine harness.

  STOP

Test Step 8. CHECK THE GROUND CIRCUIT

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

2. At contact "B" wire (200-BK) of the harness connector for the radio, measure the resistance from the ground contact on the radio to a good frame ground.

Expected Result:

The resistance measurement is less than 5 ohms.

Results:

• YES - The resistance measurement is less than 5 ohms. The ground connection is correct. Proceed to Test Step 9.

• NO - The resistance measurement is greater than 5 ohms. The ground circuit is not correct.

  Repair: There is an open or a poor connection in the ground circuit for the display.A resistance measurement that is much greater than 5 ohms but less than 5000 ohms could indicate that one of the connection points in the circuit is not open but is not a good connection.Refer to the complete Electrical System Schematic for the machine. Examine all of the connectors and splices that are in the ground circuit for the display. Ensure that the electrical connections are clean and secure. Repair the machine harness or replace the machine harness.

  STOP

Test Step 9. CHECK THE CIRCUIT FOR A SHORT TO GROUND

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

2. Remove the "AccuGrade" fuse from the fuse block. The "AccuGrade" fuse is number "17".

3. Disconnect the harness connector from the radio.

4. With the "AccuGrade" fuse removed from the fuse block, measure the resistance between frame ground and power contact "A" wire (184-BLU) on the harness for the data radio.

Expected Result:

The resistance measurement is greater than 5000 ohms.

Results:

• YES - Each resistance measurement is greater than 5000 ohms. The resistance measurement does not indicate a short to frame ground or to another circuit in the machine harness.

  Repair: Contact your technical communicator for a possible consultation with Caterpillar.

  STOP

• NO - One or more of the resistance measurements is less than 5000 ohms. There is a short to frame ground or to another ground circuit in the machine harness.

  Repair: Refer to the complete Electrical System Schematic of the machine. Check all of the connectors that are involved in the power supply circuit. Ensure that all connections are clean, that all connections are secure and that all connections are in good condition. Check the machine harness for areas that contact the machine frame. Look for worn insulation or missing insulation on the wire. Repair the machine harness or replace the machine harness.Refer to Testing and Adjusting, "Wiring Harness (Short Circuit) - Test", for more information on finding and correcting a short circuit.

  STOP