AccuGrade® Laser (CB420) Caterpillar

CB 32 ECM Disconnected

Usage:

120H ALZ

Conditions Which Generate This Code:

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No data is being received from the Grade Slope Control ECM in order to indicate the status of the hydraulics.

Test Step 1. CHECK THE FUSE OR THE CIRCUIT BREAKER FOR THE GRADE SLOPE CONTROL ECM

Locate the AccuGrade Fuse(s) and/or the AccuGrade Circuit breaker.
Note: Use the schematic for the machine in order to identify the correct fuse or the circuit breaker.

Check for a blown fuse. Check the circuit breaker in order to ensure that the breaker has not tripped.

Expected Result:

The AccuGrade Fuse(s) and/or the AccuGrade Circuit breaker are not blown or tripped.

Results:

OK - The AccuGrade Fuse(s) and/or the AccuGrade Circuit breaker are not blown or tripped. Proceed to Test Step 2.
NOT OK - The AccuGrade Fuse(s) and/or the AccuGrade Circuit breaker are blown or tripped.
Repair: Check the power circuit for short circuits to ground. Repair the harness. Replace the AccuGrade fuse(s) or reset the circuit breaker.
STOP

Test Step 2. CHECK THE POWER CIRCUIT OF THE GRADE SLOPE CONTROL ECM

Use the Electrical System Schematic in order to identify the power inputs for the Grade Slope Control ECM. Ensure that you check the power input for the Key Start Switch.

Expected Result:

All of the +Battery inputs have a system voltage.

Results:

OK - All of the + Battery inputs have system voltage. Proceed to Test Step 3.
NOT OK - All of the + Battery inputs do not have system voltage.
Repair: Check the power circuit for open circuits. Repair the harness or replace the harness.
STOP

Test Step 3. CHECK THE STATUS OF THE CONFIGURATION

Expected Result:

The installation status is set to "Installed".

Results:

OK - The installation status is set to "Installed". Proceed to Test Step 4.
NOT OK - The installation status is set to "Not Installed".
Repair: Change the status to "Installed". Click the "OK" button on the screen. Verify that the correct sales model is selected. If the sales model is incorrect, click on "Product Sales model" in order to change the parameter.
STOP

Test Step 4. TEST THE HARNESS CIRCUIT

Disconnect the connector with 6 pins (sockets) that is located on the left side from the back of the Display.

Measure the resistance between pin C on the display connector and "J2" pin 67 on the connector for the Grade Slope Control ECM.

Measure the resistance between pin D on the display connector and "J2" pin 68 on the connector for the Grade Slope Control ECM.

Expected Result:

The resistance is less than 5 ohms for each measurement.

Results:

OK - The resistance is less than 5 ohms. Proceed to test step 5.
NOT OK - The resistance is greater than 5 ohms.
Repair: Repair the harness or replace the harness.
STOP

Test Step 5. CHECK THE TERMINATION RESISTOR.

The AccuGrade - Grade Control System harness remains disconnected from all electronic control devices that use the CAN data link.

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 measurements are 120 ± 12 ohms.

Results:

YES - The resistance measurements are 120 ± 12 ohms. Reconnect the resistors.
Repair: The CAN data link circuit in the machine harness is correct. The ECM may have failed. Exit this procedure and perform this procedure for the diagnostic code again. If the cause of the diagnostic code is NOT found, contact your Caterpillar dealership.
STOP
NO - One or both resistance measurements are NOT 120 ± 12 ohms.
Repair: Replace the termination resistor(s) that did not measure 120 ± 12 ohms.
STOP