HANDLE AS 4687590 - Caterpillar

Troubleshooting Procedure
The possible causes of these failures are listed below:
The signal circuit in the harness is open.
The switch has failed.
The ECM has failed. ECM failure is unlikely.
Illustration 1 g03335764
Note: Prior to beginning this procedure, inspect the harness connectors that are involved in this circuit. Poor connections can often be the cause of a problem in an electrical circuit. Verify that all connections in the circuit are clean, secure, and in good condition. Check the wiring for pinch points or abrasions. Look for and repair areas that indicate wires are exposed. If a problem with a connection is found, correct the problem and verify that this diagnostic code is active before performing a troubleshooting procedure.
Table 1
Troubleshooting Test Steps    Expected Result    Results    
1. Check The Switch
A. Locate the switch that corresponds to the indicator that is located on the display module. (If necessary, use the Electrical Schematic to assist locating the switch).
B. Disconnect the signal wire from the switch.
C. Place a jumper wire from the signal wire to the ground wire.
   
The alert indicator is no longer active on the main display module.     OK - The alert indicator is no longer active on the main display module.
Repair: The switch has failed. Replace the switch.
STOP
NOT OK - The alert indicator remains on the main display module. The harness is open or the ECM has failed. ECM failure is unlikely.
Proceed to Test Step 2.    
2. Check The Voltage Of The ECM
A. Remove the jumper that was used in the previous test step.
B. Verify that the signal wire is still disconnected.
C. Measure the pull-up voltage from the signal wire to the ground wire with a calibrated digital multimeter.    
The voltage is either approximately 5 VDC or 12.5 VDC.     OK - The voltage is either approximately 5 VDC or 12.5 VDC.
Proceed to Test Step 4.
NOT OK - The voltage is not correct.
Proceed to Test Step 3.    
3. Check the Signal Circuit Of The Harness
A. Turn