VALVE AS-RELIEF 4N8385 - Caterpillar

Test Step 1. CHECK VOLTAGES.
Illustration 1 g00930987
Harness wire identification
Note: The voltage from the PCP to the control station processor (CSP) is approximately equal to the battery voltage minus 2 VDC. The normal operating voltage is 7.5 VDC to 32 VDC.
Table 1
Switch Input Parameters Voltage with Reference to Switch Common (Pin 12)
Input signal voltage The maximum is 5.0 VDC
Switch ON Less than 2.5 VDC
Switch OFF Greater than 3.74 VDC Expected Result:All voltages are correct.Results:
OK - All voltages are correct. Go to Test Step 2
NOT OK - All voltages ARE NOT correct.Repair: Repair the harness or replace the harness.STOPTest Step 2. VERIFY THE OPERATION OF THE BUTTON PANEL AT THE MARINE POWER DISPLAY (MPD).
Ensure that the screen for "CONTROL SYSTEM INFORMATION" is displayed on the MPD.
Monitor the "Station Button Status" while pressing and holding the suspect button. Expected Result:The indicator for "Station Button Status" indicates OFF when the button is not pressed. The indicator indicates "ON" when the button is pressed.Results:
OK - The indicator for "Station Button Status" indicates OFF when the button is not pressed. The indicator indicates ON when the button is pressed. The problem is not present.STOP
NOT OK - The indicator for "Station Button Status" does not indicate OFF when the button is not pressed OR the indicator does not indicate ON when the button is pressed. Go to Test Step 3.Test Step 3. VERIFY THE OPERATION OF THE CONTROL PANEL AT THE CONTROL STATION PROCESSOR (CSP).
Insert a 12 pin Breakout TEE at the CSP.
Ensure that the digital volt meter is set to the scale for VDC.
Insert the red probe into the suspect switch pin. Insert the black probe into the wire for switch common (pin 12). Press and hold the button while monitoring the voltage. Refer to Illustration 1Expected Result:The voltage is greater than 3.75 VDC while the button IS NOT pressed. The voltage drops to less than