PLATE 4813922 - Caterpillar

Illustration 11 g02040215
Terminal locations at the voltage converter
(Terminal 1) Keyswitch +
(Terminal 2) 24 V supply
(Terminal 3) 24 V return
(Terminal 5) 12 V supply
(Terminal 6) 12 V return
Perform a 45 N (10 lb) pull test on each of the wires in the ECM connectors and harness connectors that are associated with the circuit.
Check the fastener on each ECM connector for the proper torque. Refer to Testing and Adjusting, "Electrical Connectors - Inspect" for the correct torque values.
Check the harness and the wiring for abrasion and for pinch points. Expected Result:All connectors, pins, and sockets are coupled and/or inserted, and the harness and wiring are free of corrosion, of abrasion and of pinch points.Results:
OK - The connectors and wiring appear to be OK. Proceed to Test Step 2.
Not OK - The connectors and/or wiring are not OK.Repair: Repair the connectors or wiring and/or replace the connectors or wiring.STOPTest Step 2. Check the Operation of the Heating Element for the Suspect Sensor
Ensure that the engine control switch is in the OFF position.
Remove the suspect sensor from the exhaust system.
Turn the engine control switch to the Start position and the engine running for at least 2.5 minutes.
Allow several minutes for the heating element to heat. Use an infrared thermometer to check the temperature at the tip of the oxygen sensor. The heating element will heat the tip of the sensor to approximately 600 to 800° C (1100 to 1500° F).
Turn the engine control switch to the OFF position. Expected Result:The heating element is heating the tip of the sensor to the specification that is given above.Results:
OK - The heating element is heating the tip of the sensor to 600 to 800° C (1100 to 1500° F). The heating element is OK. Proceed to Test Step 6.
Not OK - The tip of the sensor is not heating to the correct temperature. There is a problem with the heating element. The sensor may not be receiving the correct supply voltage. Proceed to Test Step 3.Test Step 3. Measure the Voltage from the Buffer at the Sensor Connector
Disconnect the sensor connector that is between the sensor and the sensor buffer.
Turn the engine control switch to the Start position and the engine running for at least 2.5 minutes.
Use a multimeter to measure the voltage between terminal 1 (12 VDC) and terminal 2 (return) on the connector for the buffer. This connector is between the sensor and the sensor buffer.
Turn the engine control switch to the OFF position. Expected Result:12 V is available at the sensor connector.Results:
OK - 12 V available at the sensor connector.Repair: Supply voltage is available to the oxygen sensor. The heating element is not heating the sensor, but the sensor is receiving the correct voltage. There is a problem with the sensor. Replace the sensor.STOP
Not OK - 12 V is not available at the terminals of the sensor connector between the sensor and the sensor buffer. The supply voltage is not available at the sensor. There may be a problem with the sensor buffer