3408E and 3412E Industrial Engines Caterpillar

Refer to the Operation and Maintenance Manual for the location of the sensors on the engine.

The ECM supplies 5.0 ± 0.5 VDC to each analog sensor.

The analog sensor supply is output short circuit protected. A short circuit to the battery will not damage the circuit inside the ECM.

All connectors, pins, and sockets should be completely inserted and coupled. The harness and wiring should be free of corrosion, abrasion, and pinch points. All connections and grounds should be tight and free of corrosion.

Check the Sensor Supply Voltage

1. Turn the keyswitch to the ON position.

2. Disconnect the sensor. Measure the voltage across terminal A and terminal B at the harness side of the sensor connector.

3. The sensor supply voltage should be 5.0 ± 0.5 VDC at the sensor connector. If the voltage is less than 5.0 ± 0.5 VDC, the voltage is not reaching the sensor. Inspect the wiring harness and connectors on the ECM.

Check the Sensor for Internal Shorts

1. Turn the keyswitch to the OFF/RESET position and install a 7X-6370 Adapter Cable Assembly (3 Pin DT Breakout) at the sensor connector. Leave the sensor disconnected.

2. Turn the keyswitch to the ON position.

3. Measure the voltage across terminal A and terminal B.

4. Connect the sensor. The sensor supply voltage should be 5.0 ± 0.5 VDC at the sensor connector. The voltage should not drop when the sensor is connected. If the sensor pulls down the supply voltage, the sensor may be internally shorted. Refer to the Troubleshooting Guide for your engine.