Generator Set Control Panel for Switchgear Conversion Caterpillar

Illustration 1	g00565083
Schematic For The Sensor Power Supply

This service code is recorded when the main display module reads a below normal voltage for the +8 DCV sensor supply circuit.

1. Check The Voltage At The Main Display.

   1. Use a 7X-1710 Multimeter Probe in order to check themain display module connector voltage. Measure the voltage from contact 24 to contact 2 (ground). DO NOT disconnect the harness from the module.

      Expected Result: The voltage measures 8.0 ± 0.5 DCV.

      Results:

      • YES - The voltage is 8.0 ± 0.5 DCV. The sensor supply voltage is correct. Check the main display module. If the fault is still present, the main display module is faulty. Replace the module. See Testing and Adjusting, "Module - Replace". STOP.

      • NO - The voltage is NOT 8.0 ± 0.5 DCV. The sensor supply voltage is NOT correct. Proceed to Step 2.

2. Disconnect the sensors.

   1. Continue to monitor the sensor supply voltage.

   2. There are sensors that are connected to the main display module's sensor supply (+8 DCV). Disconnect one of these sensors from the machine harness.

   3. After disconnecting the sensor, check the voltage reading on the multimeter.

      Expected Result: The voltage that is measured is 8.0 ± 0.5 DCV.

      Results:

      • YES - The voltage is 8.0 ± 0.5 DCV. The sensor supply is correct. The sensor that was just disconnected is faulty. Replace the sensor. STOP.

      • NO - The voltage is NOT 8.0 ± 0.5 DCV. Repeat this test. Remove one sensor at a time and check the voltage. If the voltage is NOT correct after disconnecting all the sensors, continue to the next test. Proceed to Step 3.

3. Check for a short to ground.

   1. Turn the disconnect switch and the key start switch to the OFF position.

   2. The sensors remain disconnected.

   3. Disconnect the machine harness from the main display module.

   4. At the machine harness connector for the main display module, measure the resistance between the frame ground and the sensor supply circuit (connector contact 24).

      Expected Result: The measured resistance is greater than 5000 ohms.

      Results:

      • YES - The resistance is greater than 5000 ohms. The harness circuit resistance is correct. The main display module is faulty. Replace the module. See Testing and Adjusting, "Module - Replace". STOP.

      • NO - The resistance is less than 5000 ohms. The machine harness is faulty. There is a short to ground in the machine harness. Repair the harness or replace the harness. STOP.