5130, 5130B and 5230 Excavators, 784B, 785B, 785C, 789B, 789C, 793B and 793C Off-Highway Truck/Tractors and 992G, 994 and 994D Wheel Loaders Vital Information Management System (VIMS) Caterpillar

Illustration 1	g00501598
Engine Speed Sensor Schematic

This fault is recorded when the VIMS module reads the engine speed signal and the signal is erratic, intermittent or incorrect.

The possible causes of this fault are listed here:

• A poor electrical connection at a machine harness connector

• The sensor is loose or the sensor is not adjusted correctly.

• The signal circuit in the machine harness is shorted to ground.

• The signal circuit is shorted to + battery in the machine harness.

• The signal circuit is open in the machine harness.

• The VIMS module is faulty. This is unlikely.

1. INSPECT THE HARNESS AND INSPECT THE SENSOR.

   1. Turn the disconnect switch to the OFF position.

   2. Inspect the engine speed sensor and related machine harness connections.

   3. Verify that the engine speed sensor is clean and tight. Verify that the harness connections are clean and tight.

      Expected Result: The engine speed sensor and related wiring are correct.

      Results:

      • OK - Sensor is correct and the machine harness is correct. Proceed to 2.

      • NOT OK - Sensor has failed or the machine harness has failed. Repair the failed component. Refer to the Testing and Adjusting, "Speed Sensor - Adjust" section. STOP.

2. CHECK FOR SHORT TO GROUND IN THE SIGNAL CIRCUIT

   1. The disconnect switch remains in the OFF position.

   2. Disconnect the machine harness from the engine speed sensor.

   3. Disconnect the machine harness from the VIMS interface module.

   4. At the machine harness connector of the VIMS interface module, measure the resistance between frame ground and contact 29 (wire 450-YL(Yellow)) of the engine speed signal circuit.

      Expected Result: The resistance is greater than 5000 ohms.

      Results:

      • OK - Resistance is greater than 5000 ohms. The harness circuit is correct. Proceed to 3.

      • NOT OK - Resistance is less than 5 ohms. The machine harness has failed. There is a short between frame ground and the engine speed signal circuit in the machine harness. STOP.

3. CHECK FOR A SHORT TO THE + BATTERY CIRCUIT IN THE MACHINE HARNESS.

   1. The disconnect switch remains in the OFF position.

   2. The sensor remains disconnected and the VIMS module remains disconnected.

   3. At the machine harness connector for the VIMS module, measure the resistance between the + battery contact 1 (wire 113-OR(Orange)) and contact 29 (wire 450-YL(Yellow)) of the engine speed signal circuit.

      Expected Result: The resistance is greater than 5000 ohms.

      Results:

      • OK - Resistance is greater than 5000 ohms. The harness circuit is correct. Proceed to 4.

      • NOT OK - Resistance is less than 5 ohms. The machine harness is faulty. There is a short between the engine speed signal circuit and + battery. Repair the harness or replace the harness. STOP.

4. CHECK FOR OPEN SIGNAL CIRCUIT

   1. The disconnect switch remains in the OFF position.

   2. The sensor remains disconnected and the VIMS module remains disconnected.

   3. Measure the resistance between contact C (wire 450-YL(Yellow)) of the engine speed sensor to connector contact 29 (wire 450-YL(Yellow)) of the machine harness connector of the VIMS interface module.

      Expected Result: The resistance is less than 5 ohms.

      Results:

      • OK - Resistance is less than 5 ohms. The signal circuit in the machine harness is correct. The VIMS interface module has failed. Replace the interface module. Refer to the Testing and Adjusting, "Module - Replace" section. STOP.

      • NOT OK - Resistance is greater than 5 ohms. The machine harness is faulty. The engine speed signal circuit is open in the machine harness. Repair the machine harness or replace the machine harness. STOP.