G3500 A3 Engines Caterpillar

Use this procedure to troubleshoot the following diagnostic codes:

• 338-5 Engine Pre-Lube Pump Relay current below normal

• 338-6 Engine Pre-Lube Pump Relay current above normal

This procedure troubleshoots the output circuit for the prelube relay. Refer to Troubleshooting, "Prelubrication System" in order to troubleshoot the circuit for the prelubrication pressure switch.

The prelubrication system is an option. If Caterpillar did not supply the prelube system, the prelube function is disabled. The following codes are also disabled:

• E233 (3) Low Engine Pre-Lube Pressure

• 338-5 Engine Pre-Lube Pump Relay current below normal

• 338-6 Engine Pre-Lube Pump Relay current above normal

• 339-5 Engine Pre-Lube Pressure Switch current below normal

The prelube system is enabled when the "Engine Pre-Lube Time Out Period" is programmed for a time period that is between 30 and 300 seconds.

If the "Engine Pre-Lube Time Out Period" is programmed for a time period of zero seconds, the prelubrication is disabled. The engine will crank without the prelubrication. The E233 (3) event code and the 338-5, 338-6, and 339-5 diagnostic codes are disabled.

The prelube pump will not operate if the emergency stop button is activated or if the engine speed is greater than 0 rpm.

During the prestart, the Electronic Control Module (ECM) can energize the prelube pump before cranking the engine. The pump provides lubrication to the engine bearings. When the conditions permit operation and the logic determines that lubrication is required, the ECM provides +Battery voltage to the prelube relay. The prelube relay provides pressurized air or gas to the prelube pump motor. The prelube pump motor rotates the prelube pump. After activation, the prelube system will operate until one of the following occurrences:

• Closure of the prelubrication pressure switch

• Completion of the "Engine Pre-lube Time Out Period"

• Activation of the emergency stop button

The ECM monitors the prelubrication pressure switch in order to verify lubrication of the engine prior to start-up. The pressure switch is normally open. The pressure switch closes when the prelube pump raises the engine oil pressure to 9 ± 3 kPa (1.3 ± 0.4 psi). Closure of the pressure switch indicates that sufficient oil pressure has been achieved. After the pressure switch closes, the prelube pump continues to operate for a programmable time ("Engine Pre-Lube Time Out Period"). The engine starting sequence continues when the engine prelube sequence is complete.

If the ECM does not detect closure of the pressure switch within the programmed time, the ECM monitors the engine oil pressure sensor. The pressure determines whether lubrication has occurred. If the prelubrication does not occur, an E233 (3) Low Engine Pre-Lube Pressure is generated. The starting sequence is terminated.

The prelube pump can also be operated with a manual switch. When the switch is closed, a +Battery signal is sent to the ECM. The ECM provides +Battery voltage to the prelube relay until one of these conditions occur:

• Closure of the prelubrication pressure switch

• Activation of the manual prelube switch

• Activation of the emergency stop button

The prelubrication system also operates after shutdown. The postlube ensures that the turbocharger has adequate lubrication during coast mode. When the engine reaches 0 rpm, the output for the prelube relay will operate for 3 minutes.

The most likely causes of the diagnostic code are a poor electrical connection or a problem in a wiring harness. The next likely cause is a problem with the pressure switch. The least likely cause is a problem with the ECM.

The troubleshooting procedure may generate additional diagnostic codes. Keep your mind on correcting the cause of the original diagnostic code. Clear the diagnostic codes after the problem is resolved.

Illustration 1	g01250708
Schematic of the prelubrication system

Test Step 1. Inspect the Electrical Connectors and the Wiring

1. Set the engine control to the OFF/RESET position.

Note: For the following steps, refer to Troubleshooting, "Inspecting Electrical Connectors".

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Illustration 2	g01392084
Location of the ECM connectors that are for the prelubrication system (typical left front side engine view) (1) J2/P2 ECM connectors

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Illustration 3	g01393591
Location of the prelubrication relay (typical right rear side engine view) (2) Prelube relay

2. Thoroughly inspect ECM connectors (1) and the connectors for relay (2) .

   1. Check the allen head screw for each of the ECM connectors for the proper torque.
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   Illustration 4	g01393595
   Terminal locations at the P1 ECM connector that is for the prelubrication system (P2-12) Prelube relay (P2-22) Return

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   Illustration 5	g01393596
   Terminal locations at the interface box that is for the prelubrication system (Terminal 1) Prelube relay (Terminal 2) Manual prelube switch

   2. Perform a 45 N (10 lb) pull test on each of the wires that are associated with the circuit for the prelube relay.

   3. Check the harness and the wiring for abrasion and for pinch points from the prelube relay to the ECM.

Expected Result:

The connectors, pins, and sockets are connected properly. The connectors and the wiring do not have corrosion, abrasion, or pinch points.

Results:

• Not OK - The components are not in good condition and/or at least one connection is improper.

  Repair: Perform the necessary repairs and/or replace parts, if necessary.

  STOP

• OK - The components are in good condition with proper connections. Proceed to Test Step 2.

Test Step 2. Check for Diagnostic Codes

1. Establish communication between Caterpillar Electronic Technician (ET) and the engine ECM. Refer to Troubleshooting, "Electronic Service Tools", if necessary.

2. Check for an active 338-5 diagnostic code.

   If there is an active 338-5 diagnostic code, proceed to the "Results" for this test step. Otherwise, continue this procedure.

   Note: The 338-5 diagnostic code can only be detected when the ECM output for the prelube relay is off. The output is normally off when the engine control is in the COOLDOWN/STOP position and when the pressure switch is closed.

3. Use Cat ET to check the logged diagnostic codes. If there is a 338-6 diagnostic code, clear the code.

4. Activate the manual prelube switch for at least 30 seconds. Then release the switch.

   Note: The 338-6 diagnostic code can only be detected when the ECM output for the prelube relay is on. The output is normally on when the engine control is in the START position and the pressure switch is open.

5. Use Cat ET to look for a logged 338-6 diagnostic code.

Expected Result:

When the engine control was in the COOLDOWN/STOP position, there was no active 338-5 diagnostic code.

After the manual prelube switch was operated, there was no logged 338-6 diagnostic code.

Results:

• OK - No diagnostic codes were generated. The output for the prelube relay seems to be OK at this time. The initial diagnostic code was probably caused by a poor electrical connection.

  Repair: If there is an intermittent problem that is causing the codes to be logged, refer to Troubleshooting, "Inspecting Electrical Connectors".

  STOP

• Not OK (338-5 diagnostic code) - A 338-5 diagnostic code was activated. The code can be caused by an actual open circuit or by a short circuit to the +Battery side. Proceed to Test Step 3.

• Not OK (338-6 diagnostic code) - After the manual prelube switch was operated, a 338-6 diagnostic code was generated. Proceed to Test Step 7.

Test Step 3. Check for a Short Circuit to the +Battery Side

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Gaseous fuel is present. Personal Injury or Death can result from an open flame or spark igniting the gaseous fuel causing an explosion and/or fire. Always use a gas detector to determine the presence of gaseous fuel when maintaining and servicing. Contact your local gas provider immediately for assistance in the event of a leak.

Note: Open sparks can be generated during this test.

1. Make sure that no combustible gas is present in the surrounding atmosphere.

2. Ensure that the engine control is in the COOLDOWN/STOP position.

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High voltage. Power source must be disconnected before working on equipment. Failure to disconnect power source could result in injury or death.

3. Verify that the pressurized air for the prelube pump motor is deactivated.

4. Disconnect the harness connector for the prelube relay. Then connect the connector. Listen for an audible click from the relay.

   If the ambient noise is too loud, touch the relay when the connector is connected in order to feel the vibration. The relay will vibrate when the relay is de-energized and energized.

Expected Result:

There is no audible click and/or vibration when the connector is disconnected and connected. The relay is not energized when the engine control is in the COOLDOWN/STOP position.

Results:

• OK - There is no audible click and/or vibration when the connector is disconnected and connected. There is no short circuit to the +Battery side. There is an open circuit. Proceed to Test Step 5.

• Not OK - There is no audible click and/or vibration when the connector is disconnected and connected. The relay is receiving power when the engine control is in the COOLDOWN/STOP position. There is probably a short circuit to the +Battery side in a connector or a wiring harness. Proceed to Test Step 4.

Test Step 4. Determine the Cause of the Energized Relay

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Gaseous fuel is present. Personal Injury or Death can result from an open flame or spark igniting the gaseous fuel causing an explosion and/or fire. Always use a gas detector to determine the presence of gaseous fuel when maintaining and servicing. Contact your local gas provider immediately for assistance in the event of a leak.

Note: Open sparks can be generated during this test.

1. Remove the wires from terminal locations P2-12 and P2-22 at the ECM connector.

2. Set the engine control to the COOLDOWN/STOP position.

3. Disconnect the harness connector for the prelube relay. Then connect the connector. Listen for an audible click from the relay.

   If the ambient noise is too loud, touch the relay when the connector is connected in order to feel the vibration. The relay will vibrate when the relay is de-energized and energized.

Expected Result:

There is no audible click and/or vibration when the connector is disconnected and connected. The relay is not energized when the engine control is in the COOLDOWN/STOP position.

Results:

• OK - There is no audible click and/or vibration when the connector is disconnected and connected. The relay is not energized when the ECM is disconnected from the circuit.

  Repair: Perform the following steps:

  1. Set the engine control to the OFF/RESET position.

  2. Restore the wiring to the P2 ECM connector. Pull on the wires in order to verify proper installation of the terminals.

  3. Temporarily install a new ECM. Refer to Troubleshooting, "Replacing the ECM".

     If the problem is resolved with the new ECM, install the original ECM and verify that the problem returns. If the new ECM operates correctly and the original ECM does not operate correctly, replace the original ECM. Refer to Troubleshooting, "Replacing the ECM".

  STOP

• Not OK - There is no audible click and/or vibration when the connector is disconnected and connected. The relay is energized when the ECM is disconnected. There is a short circuit to the +Battery side in the engine harness.

  Repair: Repair the connector and/or wiring, when possible. Replace parts, if necessary. Verify that the problem is resolved.

  STOP

Test Step 5. Create a Short Circuit at the Harness Connector for the Prelube Relay

1. Set the engine control to the OFF/RESET position.

2. Disconnect the harness connector for the prelube relay.

3. Connect a jumper wire between the two terminals on the harness connector for the prelube relay.

4. Set the engine control to the COOLDOWN/STOP position.

Note: The 338-5 diagnostic code can only be detected when the ECM output for the prelube relay is off. The output is normally off when the engine control is in the COOLDOWN/STOP position and when the pressure switch is CLOSED.

5. Wait for 30 seconds and use the "Active Diagnostic" screen of Cat ET to look for a 338-5 diagnostic code.

Expected Result:

A 338-5 diagnostic code was not generated when the jumper wire was installed.

Results:

• OK - A 338-5 diagnostic code was not generated when the jumper wire was installed. The harness and the ECM are OK. There is a problem with the relay.

  Repair: Perform the following procedure:

  1. Set the engine control to the OFF/RESET position.

  2. Remove the jumper wire from the harness connector for the prelube relay.

  3. Inspect the terminals of the connectors for the prelube relay. Check the terminals for damage, for moisture, and for corrosion. Make repairs, as needed.
  If the problem is not resolved, replace the relay.

  STOP

• Not OK - A 338-5 diagnostic code was generated when the jumper wire was installed. There is an open circuit in a harness or a problem with the ECM. Proceed to Test Step 6.

Test Step 6. Create a Short Circuit at the ECM

1. Set the engine control to the OFF/RESET position.

2. Remove the wires from terminal locations P2-12 and P2-22 at the ECM connector.

3. Install a jumper wire between terminal locations P2-12 and P2-22. Pull on the jumper wire in order to verify proper installation.

4. Set the engine control to the COOLDOWN/STOP position.

Note: The 338-5 diagnostic code can only be detected when the ECM output for the prelube relay is OFF. The output is normally OFF when the engine control is in the COOLDOWN/STOP position and when the pressure switch is CLOSED.

5. Wait for 30 seconds and use the "Active Diagnostic" screen of Cat ET to look for an active 338-5 diagnostic code.

Expected Result:

There is no active 338-5 diagnostic code.

Results:

• OK - When the jumper wire was installed, there was no active 338-5 diagnostic code. The ECM detects the jumper wire at the P2 connector. However, the ECM did not detect the jumper wire at the prelube relay. There is a problem with the wiring between the P2 connector and the prelube relay. There may be a problem with a connector.

  Repair: Perform the following procedure:

  1. Set the engine control to the OFF/RESET position.

  2. Remove the jumper wire from the P2 connector.

  3. Restore the wiring at the P2 ECM connector to the original configuration. Pull on the wires in order to verify proper installation of the terminals.

  4. Repair the wiring, when possible. Replace parts, if necessary.

  STOP

• Not OK - When the jumper wire was installed, a 338-5 diagnostic code was activated. The ECM did not detect the jumper wire. There is a problem with the ECM.

  Repair: Perform the following procedure:

  1. Set the engine control to the OFF/RESET position.

  2. Remove the jumper wire from the P2 connector.

  3. Restore the wiring at the P2 ECM connector to the original configuration. Pull on the wires in order to verify proper installation of the terminals.

  4. Replace the ECM according to Troubleshooting, "Replacing the ECM". Verify that the problem is resolved.

  STOP

Test Step 7. Create an Open Circuit at the Harness Connector for the Prelube Relay

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High voltage. Power source must be disconnected before working on equipment. Failure to disconnect power source could result in injury or death.

1. Set the engine control to the OFF/RESET position.

2. Disconnect the harness connector for the prelube relay.

3. Set the engine control to the COOLDOWN/STOP position.

4. Clear the logged 338-6 diagnostic code.

Note: The 338-6 diagnostic code can only be detected when the ECM output for the prelube relay is on. The output is normally on when the engine control is in the START position and the pressure switch is OPEN.

5. Activate the manual prelube switch for at least 30 seconds. Then release the switch.

6. Look for a logged 338-6 diagnostic code.

Expected Result:

After the manual prelube switch was operated, there was no logged 338-6 diagnostic code.

Results:

• OK - When the relay was connected, a 338-6 diagnostic code was generated. When the relay was disconnected, no 338-6 diagnostic code was generated. There is a problem with the relay.

  Repair: Perform the following procedure:

  1. Set the engine control to the OFF/RESET position.

  2. Inspect the connections of the relay for damage and/or corrosion.

  3. Perform the necessary repairs.
  If the problem is not resolved, replace the relay.

  STOP

• Not OK - When the relay was connected, a 338-6 diagnostic code was generated. When the relay was disconnected, the 338-6 diagnostic code remained. There is a problem with the wiring or with the ECM. Proceed to Test Step 8.

Test Step 8. Create an Open Circuit at the ECM

1. Remove the wire from terminal location P2-12 at the P2 ECM connector.

2. Set the engine control to the COOLDOWN/STOP position.

3. Clear the logged 338-6 diagnostic code.

Note: The 338-6 diagnostic code can only be detected when the ECM output for the prelube relay is on. The output is normally on when the engine control is in the START position and the pressure switch is OPEN.

4. Activate the manual prelube switch for at least 30 seconds. Then release the switch.

5. Look for a logged 338-6 diagnostic code again.

Expected Result:

The 338-6 diagnostic code was not generated.

Results:

• OK - When the output to the relay was disconnected from the P2 ECM connector, the 338-6 diagnostic code was not generated. There is a problem with the wiring between the P2 ECM connector and the prelube relay. The problem could be in a connector.

  Repair: Perform the following procedure:

  1. Restore the wiring at the P2 ECM connectors. Pull on the wire in order to verify proper installation of the terminal.

  2. Repair the harness, when possible. Replace the harness, if necessary.

  STOP

• Not OK - A 338-6 diagnostic code was generated when the wiring was disconnected from the P2 ECM connector. There seems to be a problem with the ECM.

  Repair: Perform the following procedure:

  1. Set the engine control to the OFF/RESET position.

  2. Restore the wiring at the P2 ECM connectors. Pull on the wire in order to verify proper installation of the terminal.

  3. Replace the ECM according to Troubleshooting, "Replacing the ECM". Verify that the problem is resolved.

  STOP