LOCKNUT 4941835 - Caterpillar

Illustration 6 g01338483
Location of the +Battery side of the air inlet heater relay
Connect a test lamp between the +Battery side of the air inlet heater relay and the engine ground.Expected Result:The test lamp illuminates.Results:
OK - The test lamp illuminates. Battery voltage is reaching the relay. Proceed to Test Step 6.
Not OK - The test lamp does not illuminate. Battery voltage is not present at the relay.Repair: Verify that the fuse is not blown.If the fuse is not blown, there is an open circuit in the wiring between the battery and the relay. There may be a problem with a connector.Repair the wire and/or the connector. Replace parts, if necessary. Verify that the original problem has been resolved.STOPTest Step 6. Check for Voltage Output at the Relay
Illustration 7 g01338505
Connect a test lamp between the output terminal of the air inlet heater relay and the engine ground stud.Note: Observe the test lamp. The test lamp will be off, since the relay is not energized. If the test lamp is on, ensure that the test lamp is connected to the output side of the relay.
Turn the keyswitch to the ON position.
Activate the "Air Inlet Heater Override" on Cat ET and observe the test lamp.Note: Do not leave the "Air Inlet Heater Override" on for an extended period of time. This will prevent unnecessary cycling of the air inlet heater and the battery from discharging. The "Air Inlet Heater Override" has a one minute timer that disables the test when the time expires.
Stop the "Air Inlet Heater Override" and turn the keyswitch to the OFF position.Expected Result:The test lamp illuminated when the "Air Inlet Heater Override" was enabled.Results:
OK - The test lamp illuminated when the "Air Inlet Heater Override" was enabled. The air inlet heater relay is operating correctly. Proceed to Test Step 7.
Not OK - The test lamp did not illuminate when the "Air Inlet Heater Override" was enabled.Repair: There is a problem with the air inlet heater relay. Replace the relay. Verify that the problem is resolved.STOPTest Step 7. Check the Wiring Between the Relay and the Heating Element and Between the Heating Element and the Engine Ground
Illustration 8 g01352812
Top side engine view
(4) Supply wire for the heating element
(5) Ground strap for the heating element
Isolate wire (4) that is between the relay and the heating element. Measure the resistance of the wire that connects the relay to the air inlet heater.
Isolate ground strap (5). Measure the resistance of ground strap.Expected Result:Both of the resistance measurements prove continuity of the circuit.Results:
OK - Both of the resistance measurements prove continuity of the circuit. There is not an open circuit in the wiring for the heating element. Restore the wiring to the original configuration. Proceed to Test Step 8.
Not OK - There is an open circuit in the wiring for the heating element.Repair: Repair the wire and/or the ground strap. Replace parts, if necessary. Verify that the problem is resolved.STOPTest Step 8. Measure the Current through the Heating Element
Connect a 155-5176 AC/DC Current Probe or