3508, 3508B, 3508C, 3512, 3512B, 3512C, 3516, 3516B and 3516C Engines Caterpillar Monitoring System Caterpillar

Illustration 1	g00573764
Schematic For Sensor Power Supply

Note: The procedures that are used to troubleshoot this diagnostic code may cause additional diagnostic codes to be generated. Find the cause of the diagnostic code and repair the cause of the diagnostic code before troubleshooting any new diagnostic codes.

This diagnostic code is recorded when the Main Display Module reads the voltage of the sensor supply voltage circuit as below normal voltage. This diagnostic code is also recorded when the voltage is shorted to ground.

1. Measure the voltage at the Main Display Module.

   1. Turn the "ECS" switch to the COOLDOWN/STOP position.

   2. Use the 7X-1710 Multimeter Probe to measure the voltage at the Main Display Module from contact 24 to contact 2 (ground).

   3. Do not disconnect the harness from the Main Display Module.

      Expected Result: The voltage should be 8.0 ± 0.5 DCV.

      Results:

      • OK - The voltage is 8.0 ± 0.5 DCV. The voltage is correct. If the "SERV CODE" indicator remains ON, replace the Main Display Module. For more information, see Testing And Adjusting, "Module - Replace".

      • Not OK - The voltage is not 8.0 ± 0.5 DCV. The sensor supply voltage is incorrect. Proceed to Step 2.

2. Disconnect The Sensors.

   1. The ECS switch remains in the COOLDOWN/STOP position.

   2. Disconnect all sensors and all senders that receive +8 DCV from the Main Display Module.

   3. Use the 7X-1710 Multimeter Probe to measure the voltage from connector contact 2 (ground) to contact 24 of the Main Display Module.

      Expected Result: The voltage should be 8.0 ± 0.5 DCV.

      Results:

      • OK - The sensor supply voltage is 8.0 ± 0.5 DCV. The sensor supply voltage is correct. One of the sensors or the senders has a problem. Individually reconnect each sensor or reconnect each sender while the voltage is being monitored. The voltage should not drop below 7.5 DCV. If the voltage drops below 7.5 DCV, the sensor or the sender has a problem. Replace the sensor or replace the sender.

      • Not OK - The voltage is less than 8.0 ± 0.5 DCV. The sensor supply voltage is not correct. Proceed to Step 3.

3. Check The Harness For A Short To Ground.

   1. Turn the "ECS" switch to the OFF/RESET position.

   2. Disconnect all sensors and senders that receive +8 DCV from the Main Display Module.

   3. Disconnect the engine harness from the Main Display Module.

   4. At the engine harness connector for the Main Display Module, measure the resistance from connector contact 24 to contact 2 (ground).

      Expected Result: The resistance should be greater than 5000 ohms.

      Results:

      • OK - The resistance is greater than 5000 ohms. The harness resistance is correct. The Main Display Module has a problem. Replace the Main Display Module. For more information, see Testing And Adjusting, "Module - Replace".

      • Not OK - The resistance is less than 5000 ohms. The engine harness has a problem. There is a short between ground and the sensor supply voltage circuit in the engine harness.