FRAME AS-COUPLER 4657933 - Caterpillar

Illustration 1 g01503094
M Series Motor Grader
Illustration 2 g01503658
H Series Motor GraderThis 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.
Turn off the Display.
Turn the key start switch for the machine to the OFF position.
Turn the key start switch for the machine to the ON position.
Turn on the Display.
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 show as "Connected" in the "Diagnostics" screen.Repair: The issue was caused by the internal CAN circuit of the display. Cycling the power to the system has reset the Display. Return the machine to normal operation.STOP
NO - All of the system components do not show as "Connected" in the "Diagnostics" screen. Proceed to Test Step 2.Test Step 2. CHECK THE RESISTANCE OF THE CAN CIRCUIT.
Place the key start switch and the disconnect switch in the OFF position.
Take the following measurement at the connector for the sensor that is communicating on the AccuGrade CAN network. 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 4.
NO - The resistance measurement is NOT 60 6 ohms. Proceed to Test Step 3.Test Step 3. CHECK THE TERMINATION RESISTOR.
Disconnect the 3-pin connector for both of the termination resistors.
Measure the resistance across contact C and contact D for one resistor. Measure the resistance across contact C and contact D 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.STOPTest Step 4. CHECK THE CAN CIRCUIT FOR SHORT TO GROUND.
The key start switch and the disconnect switch remain in the OFF position.
Measure the resistance between contact C wire (L854-YL) and frame ground. Measure the resistance between contact D wire (L855-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.STOPTest Step 5. CHECK THE CAN CIRCUIT FOR SHORT TO + BATTERY.
Turn the disconnect switch and the key start switch to the ON position.
Measure the voltage between contact C wire (L854-YL) and frame ground. Measure the resistance between contact D (L855-GN) and frame ground. Note the voltage.Expected Result:The voltage measurements are approximately 2.5 VDC.Results:
YES