PUSH BLOCK GROUP 4J8078 - Caterpillar

Illustration 5 g01118589
Small terminals for the typical air inlet heater relay
Disconnect the wires from the small terminals for the air inlet heater relay.
Restore the electrical power to the ECM.
Observe the "Active Diagnostic" screen on Cat ET. Wait at least 30 seconds so that any codes may become active.
Remove the electrical power from the ECM. Expected Result:The short circuit diagnostic code (06) changed to an open circuit diagnostic code (05) when the wires to the relay were disconnected.Results:
OK - The short circuit diagnostic code (06) changed to an open circuit diagnostic code (05) when the wires to the relay were disconnected. The short circuit is in the relay.Repair: Replace the relay. Clear the diagnostic codes.Verify that the problem is resolved.STOP
Not OK - The short circuit diagnostic code (06) remained when the wires to the relay were disconnected. There is a problem in the wiring between the ECM and the relay. There may be a problem with a connector.Repair: Repair the wire and/or the connector, when possible. Replace parts, if necessary. Verify that the problem is resolved.STOPTest Step 6. Check for Battery Voltage at the Relay
Connect a test lamp between the +Battery side of the air inlet heater relay and the engine ground. Expected Result:The test lamp turns ON.Results:
OK - The test lamp turns ON. Battery voltage is reaching the relay. Proceed to Test Step 7.
Not OK - The test lamp does not turn ON. Battery voltage is not reaching the relay.Repair: There is an open circuit in the wiring between the battery and the relay. There may be a problem with a connection.Repair the wire and/or the connection, when possible. Replace parts, if necessary. Verify that the problem is resolved.STOPTest Step 7. Check for Voltage Output at the Relay
Connect a test lamp between the output terminal of the air inlet heater relay and the engine ground. Note: Observe the test lamp. The test lamp should 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.
Restore the electrical power to the ECM.
Run the "Air Inlet Heater Override" on Cat ET and observe the test lamp. Note: Do not leave the "Air Inlet Heater Override" ON. This prevents 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 remove electrical power from the ECM. Expected Result:The test lamp turned on when the "Air Inlet Heater Override" was enabled.Results:
OK - The test lamp turned on when the "Air Inlet Heater Override" was enabled. The air inlet heater relay and the +Battery connection to the air inlet heater relay are operating correctly. Proceed to Test Step 8.
Not OK - The test lamp did not turn on when the "Air Inlet Heater Override" was enabled.Repair: Replace the relay.Verify that the problem is resolved.STOPTest Step 8. Check the Wiring Between the Relay