C9 Agricultural Engine for Challenger Tractors Caterpillar

Use this procedure in order to troubleshoot the air inlet heater or use this procedure if any one of the diagnostic codes in Table 1 is active or logged.

The air inlet heater improves the engine's ability to start when the engine is cold. A reduction of white smoke is also a benefit of the air inlet heater.

The ECM activates the air inlet heater via the air inlet heater relay. The air inlet heater is activated according to the following cycles:

• Power up cycle

• Preheat cycle

• Crank cycle

• Running cycle

• Postheat cycle

The operation of the air inlet heater is determined by five different conditions:

• Power up cycle

The air inlet heater and the lamp are turned ON for 2 seconds after the ECM is first powered up. This will happen regardless of temperatures and engine speed.

• Mode of preheat

This check is for low altitude conditions. When the sum of the coolant temperature plus the inlet air temperature is less than 25° C (77° F), the ECM will turn on the heater and the lamp for 30 seconds. The ECM will turn off the heater and the lamp after 30 seconds if the engine speed remains at 0 regardless of temperature.

This check is for high altitude conditions. When the sum of the coolant temperature plus the inlet air temperature is less than 53° C (127° F), the ECM will turn on the heater and the lamp for 30 seconds. The ECM will turn off the heater and the lamp after 30 seconds if the engine speed remains at 0 regardless of temperature.

• Mode of cranking

The air inlet heater and the lamp will remain on continuously when engine speed is detected. The air inlet heater and the lamp will remain on when the sum of the coolant temperature plus the air inlet temperature is less than 25 °C (77°F) for low altitude conditions and less than 763° C (145° F) for high altitude conditions.

• Running of the engine

When the engine achieves low idle the air inlet heater and the lamp will remain on for an additional 7 minutes when the sum of the air temperature plus the coolant temperature is less than 35° C (95° F) for low altitude conditions or when the sum of the air temperature plus the coolant temperature is less than63° C (145° F) for high altitude conditions.

• Post heat cycle

The sum of the air temperature and the coolant temperature is less than 35 °C (95°F) in low altitude conditions or 63 °C (145 °F) in high altitude conditions. The air inlet heater and the lamp are cycled on and off for an additional 13 minutes. The cycle is 10 seconds on and 10 seconds off.

Illustration 1	g01381720
Schematic for the air inlet heater

Test Step 1. Inspect the Electrical Connectors and the Wiring

1. Remove the electrical power from the ECM.

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Illustration 2	g01338263
Typical left side engine view (1) Air inlet heater relay (2) Connector for the air inlet heater relay (3) Air inlet heater (4) J2/P2 ECM connectors (5) Circuit protection for the air inlet heater

2. Thoroughly inspect all of the electrical connections. Refer to Troubleshooting, "Electrical Connectors - Inspect".

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Illustration 3	g01367421
Terminal locations at the P2 ECM connector for the air inlet heater (P2-5) Air inlet heater (P2-79) Return for the air inlet heater

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Illustration 4	g01155187
Terminal locations at the connector for the air inlet heater (Terminal 1) Air inlet heater (Terminal 2) Return for the air inlet heater

3. Perform a 45 N (10 lb) pull test on each of the wires in the ECM connector that are associated with the air inlet heater.

4. Check the allen head screw for each ECM connector for the proper torque. Refer to Troubleshooting, "Electrical Connectors - Inspect".

5. Check the harness and wiring for abrasion and for pinch points from the air inlet heater back to the ECM and from the air inlet heater back to the battery.

Expected Result:

All 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 - A problem has been found with a connector and/or wiring.

  Repair: Repair the connectors or wiring and/or replace the connectors or wiring. 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.

  STOP

Test Step 2. Check for Active Diagnostic Codes

1. Connect Caterpillar Electronic Technician (ET) to the service tool connector. Refer to Troubleshooting, "Electronic Service Tools".

2. Restore the electrical power to the ECM.

3. Observe the "Active Diagnostic" screen on Cat ET. Wait at least 30 seconds so that any codes may become active.

   Look for these codes:

   • 617-5

   • 617-6

4. Remove the electrical power from the ECM.

Expected Result:

No diagnostic codes are active for the air inlet heater.

Results:

• OK - Neither of the above codes are active. There may be a problem with the secondary circuit for the air inlet heater. Proceed to Test Step 5.

• Not OK - At least one of the codes that are listed above are active. A 5 or 6 diagnostic code is active. There is a problem in the control circuit for the air inlet heater. Proceed to Test Step 3.

Test Step 3. Check for a Control Input Voltage at the Relay

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Illustration 5	g01118589
Small terminals for the typical air inlet heater relay

1. Disconnect the wires from the small terminals of the air inlet heater relay.

2. Install a test lamp across the wires.

3. Restore the electrical power to the ECM.

4. Start 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.

5. Stop the "Air Inlet Heater Override".

6. Remove the electrical power from the ECM.

Expected Result:

The test lamp illuminates while the override is active.

Results:

• OK - The test lamp illuminates while the override is active. There is a problem in the control circuit of the relay.

  Repair: Replace the air inlet heater relay. Clear any diagnostic codes. Verify that the problem is resolved.

  STOP

• Not OK - The test lamp did not turn on while the override was active. There is a problem in the harness or in a connector from the ECM to the air inlet heater relay. There may be a problem with the ECM. Return the wiring to the original configuration. Proceed to Test Step 4.

Test Step 4. Check for Proper Operation of the ECM

1. Remove the electrical power from the ECM.

2. Disconnect the J2/P2 ECM connectors.

3. Fabricate two jumper wires that are long enough to create a test circuit at the ECM connector. Crimp connector sockets to one end of each of the jumper wires.

4. Remove the wires from terminal locations P2-5 and P2-79. Install a jumper wire into each of these terminal locations.

5. Connect the J2/P2 ECM connectors.

6. Fasten the leads of the test lamp onto the ends of the jumper wires.

7. Restore the electrical power to the ECM.

8. Start 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.

9. Return the wiring to the original configuration.

10. Remove the electrical power from the ECM.

Expected Result:

The test lamp illuminates while the override is active.

Results:

• OK - The test lamp illuminates while the override is active.

  Repair: The ECM is operating correctly. The problem is in the harness or in a connector between the ECM and the air inlet heater relay. Check the resistance of the wiring in the harness in order to isolate the problem. Repair the harness and/or the connectors. Replace parts, if necessary. Verify that the repair eliminates the original problem.

  STOP

• Not OK - The test lamp did not illuminate while the override was active.

  Repair: There is a problem with the ECM. Perform the following procedure:

  1. Temporarily connect a test ECM.

     Refer to Troubleshooting, "ECM - Replace".

  2. Recheck the circuit in order to ensure that the original problem has been resolved.

     If the problem is resolved with the test ECM, install the suspect ECM. If the problem returns with the suspect ECM, replace the ECM. Verify that the problem is resolved.

     If the problem is not resolved with the test ECM, install the original ECM. There is a problem in the wiring.

  STOP

Test Step 5. Check for Battery Voltage at the Relay

1. 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: 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.

  STOP

Test Step 6. Check for Voltage Output at the Relay

1. Restore the electrical power to the ECM.

2. 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.

3. Stop the "Air Inlet Heater Override" and remove the electrical power from the ECM.

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.

  STOP

Test Step 7. Check the Wiring Between the Relay and the Heating Element and Between the Heating Element and the Engine Ground

1. Isolate the wire that is between the relay and the heating element. Measure the resistance of the wire that connects the relay to the air inlet heater.

2. 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.

  STOP

Test Step 8. Measure the Current through the Heating Element

1. Connect a 155-5176 AC/DC Current Probe or an equivalent inductive pickup clamp around wire (1) between the relay and the air inlet heater.

2. Connect the current probe to a multimeter.

3. Restore the electrical power to the ECM.

4. Run the "Air Inlet Heater Override" on Cat ET and observe the current reading on the multimeter.

   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.

5. Stop the "Air Inlet Heater Override" and remove the electrical power from the ECM.

Expected Result:

For 12 volt systems, the current reading is between 82 and 102 Amperes. The voltage reading is approximately 11 VDC.

For 24 volt systems, the current reading is between 77 and 95 Amperes. The voltage reading is approximately 22 VDC.

Note: If the voltage reading does not match the specified value, you will need to adjust the current value accordingly. For slightly lower voltages, the current value will be slightly lower. For slightly higher voltages, the current value will be slightly higher.

Results:

• OK - The readings are within the specified ranges.

  Repair: The readings are within the specified ranges. The air inlet heater circuit appears to be operating correctly at this time. There may be an intermittent problem in one of the circuits for the air inlet heater. If an intermittent problem is suspected, refer to Troubleshooting, "Electrical Connectors - Inspect".

  STOP

• Not OK - The voltage reading and/or the current reading is not within the specified ranges.

  Repair: Replace the heating element. Verify that the problem is resolved.

  STOP