AccuGrade® Laser (CB420) Caterpillar

AS 1 Memory Fault

Usage:

120H ALZ

Conditions Which Generate This Code:

This diagnostic code is active when there are too many error messages on the CAN data link.

Test Step 1. CHECK IF THE DIAGNOSTIC CODE REMAINS

Move the "Power/Setup" Switch for the display to the "OFF" position.

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

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

Move the "Power/Setup" Switch for the display to the "ON" position.

Expected Result:

The diagnostic code is no longer active.

Results:

OK - The diagnostic code is no longer active. An issue with the internal software probably caused the diagnostic code.
Repair: Resume normal machine operation.
STOP
NOT OK - The diagnostic code is still active. Proceed to Test Step 2.

Test Step 2. CHECK THE RESISTANCE OF THE CAN CIRCUIT

Show/hide table




Illustration 1	g01379685

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

Take the following measurement at the Connector for the Right or Left Hand laser/sonic harness. Measure the resistance between contact C (wire L854-YL) and contact D (wire L855-GN).

Expected Result:

The resistance measurement is 60 ± 6 ohms.

Results:

YES - The resistance measurement is 60 ± 6 ohms. Proceed to Test Step 5.
NO - The resistance measurement is NOT 60 ± 6 ohms. Proceed to Test Step 3.

Test Step 3. CHECK THE CAN TERMINATION RESISTORS.

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

Disconnect the 3-pin connector for all four of the termination resistors.

Measure the resistance between contact A (wire L854-YL) and contact B (wire L855-GN) for all of the resistors. Note the resistance.

Expected Result:

The resistance measurement is 120 ± 12 ohms.

Results:

YES - The resistance measurement is 120 ± 12 ohms. Reconnect the resistors. Proceed to Test Step 5.
NO - One or all resistance measurements is NOT 120 ± 12 ohms.
Repair: Replace the termination resistor(s) that did not measure 120 ± 12 ohms.
STOP

Test Step 4. CHECK THE HIGH CIRCUIT OF THE CAN DATA LINK FOR SHORTS

Move the "Power/Setup"Switch on the display to the "OFF" position.

Turn the key start switch and the disconnect switch for the machine to the "OFF" position.

Disconnect all of the sensors that are connected to the harness.
- Laser Receivers
- Angle Sensors
- Rotation Sensor

Show/hide table




Illustration 2	g01189993

Take the following measurements at the Connector on the Left or the Right Knuckle. Measure the resistance between the contacts that are listed in Table 1.

Show/hide table

Table 1
Harness Connector at Angle Sensor
Check from Pin C to Pin A
Check from Pin C to Pin B
Check from Pin C to Pin C
Check from Pin C to Pin D
Check from Pin C to Pin E
Check from Pin C to Pin F
Check from Pin C to Pin G

Expected Result:

The resistance measurement is greater than 5000 ohms.

Results:

OK - All of the resistances that were measured are greater than 5000 ohms. The machine harness is correct. Proceed to Test Step 5.
NOT OK - One or more of the resistances that were measured is less than 5000 ohms. The resistance measurement is not correct. There is an short circuit in the machine harness.
Repair: The short is in the machine harness. Repair the machine harness or replace the machine harness.
STOP

Test Step 5. CHECK THE LOW CIRCUIT OF THE CAN DATA LINK FOR SHORTS

Move the "Power/Setup"Switch on the display to the "OFF" position.

Turn the key start switch and the disconnect switch for the machine to the "OFF" position.

Disconnect all of the sensors that are connected to the harness.
- Laser Receivers
- Angle Sensors
- Rotation Sensor

Show/hide table




Illustration 3	g01189993

Take the following measurements at the Connector on the Left or the Right Knuckle. Measure the resistance between the contacts that are listed in Table 2.

Show/hide table

Table 2
Harness Connector at Angle Sensor
Check from Pin C to Pin A
Check from Pin C to Pin B
Check from Pin C to Pin C
Check from Pin C to Pin D
Check from Pin C to Pin E
Check from Pin C to Pin F
Check from Pin C to Pin G

Expected Result:

The resistance measurement is greater than 5000 ohms.

Results:

OK - All of the resistances that were measured are greater than 5000 ohms. The machine harness is correct. Proceed to Test Step 6.
NOT OK - One or more of the resistances that were measured is less than 5000 ohms. The resistance measurement is not correct. There is an short circuit in the machine harness.
Repair: The short is in the machine harness. Repair the machine harness or replace the machine harness.
STOP

Test Step 6. CHECK IF THE DIAGNOSTIC CODE REMAINS

Reconnect all the connections for the harness.

Reconnect the harnesses for the AccuGrade - Grade Control System to all system components.

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

Move the "Power/Setup" Switch for the display to the "ON" position.

Expected Result:

The diagnostic code is no longer active.

Results:

OK - The diagnostic code is no longer active. The diagnostic code was probably caused by a poor connection at one of the harness connectors.
Repair: Resume normal machine operation.
STOP
NOT OK - The diagnostic code is still active.
Repair: Contact your Technical communicator for a possible consultation with Caterpillar.
STOP