SHEET AS 2504995 - Caterpillar

Illustration 1 g01227576
Mode select switch connectionsThe mode select switch is the left push-button switch on the electronic hydraulic blade control handle. The switch provides a Normally Closed input of the ECM and the switch has a Normally Open input to the ECM. This switch is used to indicate to the ECM that the Accugrade system should go to AUTO mode. This diagnostic code is recorded when the ECM detects that the voltage of one or both of the switch inputs as being below normal. There is a short to ground. The possible causes of this diagnostic code are listed:
The switch has failed.
The Normally Open circuit of the switch is shorted to ground.
The Normally Closed circuit of the switch is shorted to ground.
The ECM has failed. This is unlikely. Note: Ensure that CID 0874 FMI 04 active before performing this procedure. Note: The following test procedure may create other diagnostic codes. Ignore these created diagnostic codes and clear the diagnostic codes when the problem has been corrected.System Response:The diagnostic code will cause the pedal to stop functioning. The diagnostic code will not affect any other machine operations.Test Step 1. CHECK THE SWITCH
Turn the disconnect switch and the key start switch to the ON position.
Ensure that the diagnostic code is active.
Observe the status of the diagnostic code. Then, disconnect the 12 contact machine harness connector from the blade control handle.Expected Result:The diagnostic code will remain active if the switch is not the cause of the diagnostic code. The switch is the cause of the diagnostic code if the diagnostic code is NO longer active.Results:
OK - The diagnostic code remains active. The switch has not failed. The machine harness may have failed or the ECM may have failed. Proceed to Test Step 2.
NOT OK - The diagnostic code is NO longer active. The machine harness and the ECM are operating properly.Repair: The switch has failed. Replace the blade control handle.STOPTest Step 2. CHECK THE SIGNAL CIRCUIT FOR A SHORT TO GROUND
The blade control handle 12 contact connector remains disconnected from the machine harness.
Turn the key start switch and the disconnect switch to the OFF position.
Disconnect the J1 and J2 machine harness connectors from the ECM.
At machine harness connector J1, measure the resistance from contact J1-63 (wire J943-GN) to all possible sources of ground including frame ground. Measure the resistance to all J1 and J2 connector contacts.
At machine harness connector J2, measure the resistance from contact J2-54 (wire J944-BU) to all possible sources of ground including frame ground. Measure the resistance to all J1 and J2 connector contacts.Expected Result:Each resistance measurement is greater than 5000 ohms.Results:
OK - Each resistance measurement is greater than 5000 ohms. The machine harness is correct. Proceed to Test Step 3.
NOT OK - One or more of the resistance measurements is NOT correct. The machine harness has failed.Repair: There is a short in the machine harness. The short is between either wire J943-GN or wire J944-BU in the switch circuit and the circuit with a low resistance