C9 Marine Engines Caterpillar

Use this procedure to troubleshoot any suspect problems with the air inlet heater circuit.

This procedure covers the following diagnostic codes:

• 617-05 Air Inlet Heater Relay open/current below normal

• 617-06 Air Inlet Heater Relay grounded/current above norm

The air inlet heater improves the engine's ability to start when the engine is cold. The air inlet heater also reduces white smoke when the engine is cold.

The Electronic Control Module (ECM) controls the operation of the air inlet heater via the air inlet heater relay.

The operation of the air inlet heater is determined by the following cycles:

Power Up Cycle - The air inlet heater is turned on for two seconds after the ECM is first powered up. This will happen regardless of temperatures and engine speed.

Preheat Cycle - If the "SUM" of the coolant temperature and the inlet manifold air temperature is less than 25 °C (109 °F), then the heater will remain on up to 30 seconds. If the engine speed is zero after 30 seconds, the heater is turned off regardless of the temperature.

Crank Cycle - If the "SUM" of the coolant temperature and the inlet manifold air temperature is still less than 25 °C (109 °F), the air inlet heater will remain on while the engine is being cranked.

Running Cycle - If the "SUM" of the coolant temperature and the inlet manifold air temperature is less than 35 °C (127 °F), then the air inlet heater will remain on for seven minutes.

Postheat Cycle - The air inlet heater is cycled on and off for an additional 13 minutes if the "SUM" of the coolant temperature and the inlet manifold air temperature is still less than 35 °C (127 °F). The air inlet heater will turn on for ten seconds and the air inlet heater will turn off for ten seconds.

Note: When you convert the "SUM" of two temperatures that are in degrees Celsius, the resulting value in degrees Fahrenheit will be incorrect. The two temperatures must be converted prior to the addition of the two values.

• Convert the reading for the coolant temperature from degrees Celsius to degrees Fahrenheit.

• Convert the reading for the inlet manifold air temperature from degrees Celsius to degrees Fahrenheit.

• Add the two conversions together in order to arrive at the correct conversion for the sum in degrees Fahrenheit. Refer to the example that is in Table 1.

Illustration 1	g01094719
Schematic of the circuit for the air inlet heater

Test Step 1. Inspect Electrical Connectors and Wiring

1. Remove power from the ECM.

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Illustration 2	g01192792
Typical component locations (1) Air inlet heater relay (2) Air inlet heater (3) J2/P2 ECM connectors (4) Circuit breaker for the air inlet heater (135A)

2. Thoroughly inspect all connections for components (1) and (3). Also, thoroughly inspect connectors (2) and (4). Refer to Troubleshooting, "Electrical Connectors - Inspect" for details.

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Illustration 3	g01093277
P2 terminal locations for the air inlet heater (P2-9) Air inlet heater − (P2-12) 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 at each ECM connector for the proper torque. Refer to Troubleshooting, "Electrical Connectors - Inspect" for the correct torque values.

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.

6. Check the circuit breaker for an open condition.

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.

2. Restore power to the ECM.

   Note: Ensure that the parameter for the "Air Inlet Heater Installation Status" is configured to Installed.

3. Start the "Air Inlet Heater Override" on Cat ET and observe the test lamp.

   Note: Do not leave the "Air Inlet Heater Override" ON. Avoid unnecessary cycling of the air inlet heater in order to prevent the battery from discharging. The "Air Inlet Heater Override" has a one minute timer that disables the test when the time expires.

4. Stop the "Air Inlet Heater Override".

5. Remove power from the ECM.

Expected Result:

One of the following diagnostic codes is active:

• 617-05

• 617-06

Results:

• 617-05 is Active - The ECM detects an open circuit between the air inlet heater relay and the ECM. Proceed to Test Step 3.

• 617-06 is Active - The ECM detects a short circuit between the air inlet heater relay and the ECM. Proceed to Test Step 4.

• No Codes are Active - There are no active diagnostic codes for the air inlet heater relay. Proceed to Test Step 6.

Test Step 3. Check for an Open Circuit in the Air Inlet Heater Relay's Control Circuit

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Illustration 4	g01118589
Small terminals for the air inlet heater relay's control circuit (typical example)

1. Disconnect the wires from the small terminals for the air inlet heater relay's control circuit.

2. Install a test lamp across the wires.

3. Restore power to the ECM.

4. Start the "Air Inlet Heater Override" on Cat ET and observe the test lamp.

   Note: The "Air Inlet Heater Override" has a one minute timer in order to disable the test when the time expires.

5. Stop the "Air Inlet Heater Override".

6. Remove power from the ECM.

Expected Result:

The test lamp illuminated while the override was active.

Results:

• OK - The test lamp illuminated while the override was active. The open circuit is in 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 illuminate while the override was active. Leave the wires disconnected from the small terminals of the relay. Proceed to Test Step 5.

Test Step 4. Check for a Short Circuit to the Coil of the Air Inlet Heater Relay

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Illustration 5	g01118589
Small terminals for the air inlet heater relay's control circuit (typical example)

1. Disconnect the wires from the small terminals for the air inlet heater relay's control circuit.

2. Restore power to the ECM.

3. Start the "Air Inlet Heater Override" on Cat ET.

   Note: The "Air Inlet Heater Override" has a one minute timer in order to disable the test when the time expires.

4. Stop the "Air Inlet Heater Override".

5. Remove power from the ECM.

Expected Result:

The short circuit diagnostic code 06 changed to an open circuit diagnostic code 05 when the control wires to the air inlet heater relay were disconnected.

Results:

• OK - The short circuit diagnostic code changed to an open circuit diagnostic code.

  Repair: There is a short circuit in the air inlet heater relay. Replace the air inlet heater relay and clear the diagnostic codes. Verify that the repair eliminates the problem.

  STOP

• Not OK - The short circuit diagnostic code did not change. Proceed to Test Step 5.

Test Step 5. Check the Operation of the ECM by Creating an Open and Short at the ECM Connector

1. Check the operation of the ECM by creating an open at the ECM.

   1. Remove power from the ECM.

   2. Disconnect the P2 ECM connector. Thoroughly inspect both halves of the connector for signs of corrosion and/or for moisture.

   3. Remove the wires for the air inlet heater relay from the P2 ECM connector. Install wire jumpers with Deutsch sockets into the sockets for the air inlet heater relay. Ensure that the wire jumpers are not touching any other wires. Reconnect the P2 connector.

   4. Restore power to the ECM.

   5. Start the "Air Inlet Heater Override" on Cat ET.

      Note: The "Air Inlet Heater Override" has a one minute timer in order to disable the test when the time expires.

      A 05 diagnostic code should be active for the air inlet heater relay.

   6. Remove power from the ECM.

2. Check the operation of the ECM by creating a short at the ECM.

   1. Install a jumper wire between the two wire jumpers for the air inlet heater relay that were installed in the previous step.

   2. Restore power to the ECM.

   3. Start the "Air Inlet Heater Override" on Cat ET.

      Note: The "Air Inlet Heater Override" has a one minute timer in order to disable the test when the time expires.

      A 06 diagnostic code should be active for the air inlet heater relay.

   4. Remove power from the ECM.

   5. Remove the wire jumpers and reconnect ECM connector J2/P2.

Expected Result:

An open circuit diagnostic code 05 is active when the wires for the air inlet heater relay are removed from the ECM connector. A short circuit diagnostic code 06 is active when the jumper wire is installed across the wires for the air inlet heater relay.

Results:

• OK - The ECM is working properly. The problem is in the wiring between the ECM and the air inlet heater relay.

  Repair: Repair the wires and/or the connector.

  STOP

• Not OK - One of the following conditions exists: The open circuit diagnostic code 05 is not active when the harness is disconnected. The short circuit diagnostic code 06 is not active when the jumper wire is installed.

  Repair: Perform the following repair:

  1. Temporarily connect a spare ECM.

  2. Remove all jumper wires and reconnect all connectors and wires.

  3. Recheck the system for active diagnostic codes.

  4. Repeat this test step.

  5. If the problem is resolved with the spare ECM, reconnect the suspect ECM.

  6. If the problem returns with the suspect ECM, replace the ECM.

  7. Verify that the repair eliminates the problem.

  STOP

Test Step 6. Check for Battery Voltage to the Air Inlet Heater Relay

1. Remove the wire from the +Battery side of the air inlet heater relay.

2. Connect a test lamp between the wire from the +Battery side of the air inlet heater relay and engine ground.

3. Restore power to the ECM.

4. Observe the test lamp.

5. Remove power from the ECM.

Expected Result:

The test lamp illuminated.

Results:

• OK - The test lamp illuminated. Battery voltage is reaching the air inlet heater relay. Proceed to Test Step 7.

• Not OK - The test lamp did not illuminate.

  Repair: Battery voltage is not reaching the relay. Ensure that the circuit breaker is not tripped. Repair the harness from the battery to the air inlet heater relay. Verify that the repair eliminates the problem.

  STOP

Test Step 7. Check for Voltage Output at the Air Inlet Heater Relay

1. Reconnect the wire from the +Battery to the air inlet heater relay.

2. Remove the wire to the air inlet heater from the air inlet heater relay.

3. Connect a test lamp between the output terminal of the air inlet heater relay and engine ground.

4. Restore power to the ECM.

5. Observe the test lamp. The test lamp should not be illuminated, since the air inlet heater relay is not energized. If the test lamp is illuminated, ensure that the test lamp is connected to the output side of the air inlet heater relay.

6. Run the "Air Inlet Heater Override" on Cat ET and observe the test lamp.

   Note: The "Air Inlet Heater Override" has a one minute timer in order to disable the test when the time expires.

7. Stop the "Air Inlet Heater Override".

8. Remove power from the ECM.

Expected Result:

The test lamp illuminated while the override was active.

Results:

• OK - The test lamp illuminated while the override was active. 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 illuminate while the override was active.

  Repair: Replace the air inlet heater relay.Verify that the repair eliminates the problem.

  STOP

Test Step 8. Check the Wiring Between the Air Inlet Heater Relay and the Air Inlet Heater

1. Reconnect the wire from the air inlet heater relay to the air inlet heater.

2. Disconnect the wire between the air inlet heater relay and the air inlet heater from the air inlet heater.

3. Connect a test lamp between the wire at the air inlet heater and engine ground.

4. Restore power to the ECM.

5. Run the "Air Inlet Heater Override" on Cat ET and observe the test lamp.

   Note: The "Air Inlet Heater Override" has a one minute timer in order to disable the test when the time expires.

6. Stop the "Air Inlet Heater Override".

7. Remove power from the ECM.

8. Reconnect the wire between the air inlet heater relay and the air inlet heater.

Expected Result:

The test lamp illuminated while the override was active.

Results:

• OK - The test lamp illuminated while the override was active. The wire from the air inlet heater relay to the air inlet heater is OK. Proceed to Test Step 9.

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

  Repair: There is an open in the wire between the air inlet heater relay and the air inlet heater. Replace the wire. Verify that the repair eliminates the problem.

  STOP

Test Step 9. Measure the Current through the Air Inlet Heater

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

2. Connect the current probe to a multimeter.

3. Restore 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. Avoid unnecessary cycling of the air inlet heater in order to prevent the battery from discharging. The "Air Inlet Heater Override" has a one minute timer in order to disable the test when the time expires.

5. Stop the "Air Inlet Heater Override".

6. Remove power from the ECM.

Expected Result:

The current reading is between 77 and 95 Amperes.

Results:

• OK - The current is within the specified ranges.

  Repair: The current is within the specified ranges. The air inlet heater circuit appears to be operating correctly at this time. If an intermittent problem is suspected, refer to Troubleshooting, "Electrical Connectors - Inspect".

  STOP

• Not OK - The current reading is not within the specified ranges.

  Repair: Check continuity of the wire between the air inlet heater and engine ground. Check the connections at the air inlet heater and at engine ground for corrosion. If the wire between the air inlet heater and engine ground is OK, replace the air inlet heater.Verify that the problem is resolved.

  STOP