ANGLE B137960 - Caterpillar

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Operator control (main console) (1) Indicator for the air inlet heaterThe air inlet heater lamp is located on the main console. The Electronic Control Module (ECM) provides 24 VDC to the lamp circuit. The air inlet heater lamp is used to indicate that the air inlet heater is on.The ECM momentarily illuminates the air inlet heater lamp after the ECM is powered up in order to run diagnostics on the lamp circuit. This also provides a visual check of the lamp's operation.
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Schematic for the air inlet heater lampTest Step 1. Inspect the Electrical Connectors and the Wiring
Remove the electrical power from the ECM.
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Typical left side view of the engine (1) J1/P1 ECM connectors
Thoroughly inspect connectors (1). Refer to diagnostic functional tests Troubleshooting, "Electrical Connectors - Inspect".
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P1 terminals that are associated with the air inlet heater lamp (P1-30) Air inlet heater lamp (P1-48) 24 VDC
Perform a 45 N (10 lb) pull test on each of the wires that are associated with the air inlet heater lamp.
Check the torque of the allen head screws for the ECM connectors. Refer to diagnostic functional tests Troubleshooting, "Electrical Connectors - Inspect" for the correct torque values.
Check the harness and the wiring for abrasion and for pinch points from the air inlet heater lamp back to the ECM.Expected Result:All of the connectors, pins and sockets are completely coupled and/or inserted and the harness and wiring are free of corrosion, of abrasion and of pinch points.Results:
OK - The harness and connectors appear to be OK. Proceed to Test Step 2.
Not OK - The connectors and/or wiring are not OK.Repair: Repair the wiring and/or the connectors. Replace parts, if necessary. Ensure that all of the seals are properly in place and ensure that the connectors are completely coupled. Verify that the repair eliminates the problem.STOPTest Step 2. Check for Normal Operation of the Air Inlet Heater Lamp
Restore the electrical power to the ECM.Expected Result:The air inlet heater lamp turns on momentarily. Then, the lamp turns off.Results:
OK - The air inlet heater lamp turns on momentarily. Then, the lamp turns off.Repair: The problem appears to be resolved. The original problem was probably caused by a poor electrical connection. If an intermittent problem is suspected, refer to diagnostic functional tests Troubleshooting, "Electrical Connectors - Inspect".STOP
Not OK - The air inlet heater lamp does not turn on. Proceed to Test Step 3.Test Step 3. Check for Voltage at the Lamp SocketUse a test lamp to check for voltage at the socket for the air inlet heater lamp within the first three seconds after the electrical power to the ECM is restored.Expected Result:The test lamp illuminates momentarily after the electrical power to the ECM is restored.Results:
OK - The test lamp illuminates momentarily after the electrical power to the ECM is restored.Repair: Replace the bulb.Verify that the repair eliminates the problem.STOP
Not OK - The test lamp did not illuminate momentarily after the electrical power to the ECM is restored. Proceed to Test Step 4.Test Step 4. Test