G3516C, G3516E, and G3512E Generator Set Engines Caterpillar

Use this procedure to troubleshoot suspect problems with the circuit for the indicator lamps.

This procedure covers the following diagnostic codes:

• 323-3 Engine Shutdown Lamp : Voltage Above Normal

• 324-3 Warning Lamp (Action) : Voltage Above Normal

• 443-3 Crank Terminate Relay : Voltage Above Normal

• 445-3 Run Relay : Voltage Above Normal

The Electronic Control Module (ECM) has four outputs in order to indicate the status of engine operation: "Run Relay", "Crank Terminate Relay", "Engine Control Alarm Status" and "Fault Relay". These outputs can be used to energize indicator lamps or the outputs can be used to interface with other controls.

The ECM opens an internal circuit in order to set an output to OFF. The ECM closes the circuit in order to set the output to ON. When the circuit is closed and the output is ON, the ECM allows a maximum current of 0.3 amperes to flow through the circuit to a ground that is inside the ECM.

If excessive current flows through the circuit, a diagnostic code is generated. A short circuit to the +Battery side will also activate a diagnostic code.

Note: These circuits do not sink enough current for illumination of standard incandescent lights. If a lamp is burned out, replace the lamp with the lamp that is specified in the engine's Parts Manual.

"Run Relay" - This output indicates that the engine is in the "Run" status. The engine will start soon or the engine is running. While this output is energized, a short circuit to a positive voltage source or excessive current through the circuit will cause a diagnostic code to become activated. The ECM cannot diagnose this output while the output is OFF.

"Crank Terminate Relay" - This output indicates that the engine rpm is greater than the programmed engine speed that is required for disengagement of the starting motor. While this output is energized, a short circuit to a positive voltage source or excessive current through the circuit will cause a diagnostic code to become activated. The ECM cannot diagnose this output while the output is OFF.

"Engine Control Alarm Status" - This is the alarm output. This output indicates that the ECM has detected an electrical problem or an abnormal operating condition. While this output is energized, a short circuit to a positive voltage source or excessive current through the circuit will cause a diagnostic code to become activated. The ECM cannot diagnose this output while the output is OFF.

"Fault Relay" - This is the shutdown output. This output indicates that a potentially damaging operating condition was detected by the ECM. The ECM has shut down the engine. While this output is energized, a short circuit to a positive voltage source or excessive current through the circuit will cause a diagnostic code to become activated. The ECM cannot diagnose this output while the output is OFF.

Note: Some indicators may obtain the status of the engine via a data link. If all of the indicators are not directly controlled by the ECM, do not proceed with this test.

A 323-3 or 324-3 diagnostic code can only be generated if a shutdown condition or an alarm condition is active. Failure to correct these serious conditions can result in engine damage.

Use Caterpillar Electronic Technician (ET) to determine the event code or the diagnostic code that corresponds to the 323-3 or 324-3 diagnostic code. Troubleshoot that event code or that diagnostic code before you troubleshoot the 323-3 or 324-3 diagnostic code. Refer to Troubleshooting, "Symptom Troubleshooting" or Troubleshooting, "Diagnostic Trouble Codes".

The most likely causes of a diagnostic code for a status indicator is a poor electrical connection or a problem in a wiring harness. The next likely cause is a problem with an indicator. The least likely cause is a problem with the ECM.

Logged diagnostic codes provide a historical record. Before you begin this procedure, use Cat ET to print the logged codes to a file.

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	g01326256
Schematic for the status indicators

Test Step 1. Inspect the Electrical Connectors and Wiring

1. Remove the electrical power from the engine.

2. Thoroughly inspect each of the following connectors:

   • J2/P2 connectors

   • J6/P6 connectors

   1. Check the torque of the allen head screw for the ECM connectors.

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

      Note: These outputs do not provide enough current for illumination of standard incandescent lights. If a lamp is burned out, replace the lamp with the lamp that is specified in the engine's Parts Manual.

   3. Inspect the wiring and the receptacles for the status indicators.

   4. Check the harness and wiring for abrasion and for pinch points from the customer's equipment to the ECM.

Expected Result:

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

Results:

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

• 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

Test Step 2. Check for Diagnostic Codes

1. Connect Cat ET to the service tool connector on the terminal box. Refer to Troubleshooting, "Electronic Service Tools".

2. Restore the electrical power to the engine.

3. Attempt to start the engine and observe the status indicators. Allow a minimum of 30 seconds for any diagnostic codes to activate. Use the "Active Diagnostic" screen on Cat ET to look for the codes that are listed in Table 1:
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   Table 1

   Diagnostic Codes and Descriptions with Corresponding ECM Outputs
   Code	Description	ECM Output
   323-3	Engine Shutdown Lamp : Voltage Above Normal	"Fault Relay"
   324-3	Warning Lamp (Action) : Voltage Above Normal	"Engine Control Alarm Status"
   443-3	Crank Terminate Relay : Voltage Above Normal	"Crank Terminate Relay"
   445-3	Run Relay : Voltage Above Normal	"Run Relay"

Expected Result:

There are no active diagnostic codes. The "Engine On" indicator and the "Crank Terminate" indicator (if equipped) illuminated normally. The "Active Alarm" indicator and the "Engine Failure" indicator did not illuminate.

Results:

• Yes (Original 443-3 or 445-3 Diagnostic Code) - The original diagnostic code was 443-3 or 445-3. When the engine was started, the "Run Relay" indicator and the "Crank Terminate Relay" indicator (if equipped) illuminated normally. The "Engine Control Alarm Status" indicator and the "Fault Relay" indicator did not illuminate. There are no active diagnostic codes.

  Repair: The outputs for the status indicators seem to be operating correctly at this time. The original diagnostic code was probably caused by a poor electrical connection.

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

  STOP

• Yes (Original 323-3 or 324-3 Diagnostic Code) - The original diagnostic code was 323-3 or 324-3. When the engine was started, the "Run Relay" indicator and the "Crank Terminate Relay" indicator (if equipped) illuminated normally. The "Engine Control Alarm Status" indicator and the "Fault Relay" indicator did not illuminate. There are no active diagnostic codes.

  Repair: The 323-3 and 324-3 diagnostic codes can only be activated when the corresponding indicator is activated. There may still be a problem with the output for the alarm indicator or the shutdown indicator. The alarm and/or the shutdown must be activated.

  Allow the engine operation to continue. Proceed to Test Step 3.

• Not OK (Active 323-3 or 324-3 Diagnostic Code) - There is an active 323-3 or 324-3 diagnostic code. There must be a shutdown condition before a 323-3 diagnostic code can be generated. There must be an alarm condition before a 324-3 diagnostic code can be generated. Both of these conditions are serious.

  Repair: Use Cat ET to determine the event code or the diagnostic code that corresponds to the 323-3 or 324-3 diagnostic code. Troubleshoot that event code or that diagnostic code before you troubleshoot the 323-3 or 324-3 diagnostic code. Refer to Troubleshooting, "Symptom Troubleshooting" or Troubleshooting, "Diagnostic Trouble Codes".

  Exit this procedure. After you have resolved the condition, return to this procedure in order to troubleshoot the 323-3 and/or 324-3 diagnostic code, if necessary.

  STOP

• Not OK (Active 443-3 or 445-3 Diagnostic Code) - When the engine was started, the "Run Relay" indicator and/or the "Crank Terminate Relay" indicator (if equipped) did not illuminate normally. The "Engine Control Alarm Status" indicator and the "Fault Relay" indicator did not illuminate. A 443-3 or 445-3 diagnostic code was activated. There is a problem with the output for the "Run Relay" indicator and/or the "Crank Terminate Relay" indicator (if equipped). Proceed to Test Step 4.

Test Step 3. Check for Proper Operation of the Status Indicators for the Alarm and Shutdown

Note: All active diagnostic codes and active event codes must be cleared in order for the "Engine Control Alarm Status" indicator to be OFF.

Allow the engine operation to continue for this procedure. Operate the engine under low load.

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Illustration 2	g01065357
Typical right side view (1) Unfiltered engine oil pressure sensor (2) Filtered engine oil pressure sensor

1. During engine operation, disconnect the connector for the unfiltered engine oil pressure sensor (1). Observe the "Engine Control Alarm Status" indicator on the control panel (if equipped).

   If you are only troubleshooting a 324-3 diagnostic code, proceed to the “Expected Result”.

   Note: When the filtered engine oil pressure sensor is disconnected, the engine will shut down.

2. Disconnect the connector for the filtered engine oil pressure sensor (2). Observe the "Fault Relay" indicator on the control panel (if equipped).

3. Use the "Diagnostics" screen on Cat ET to look for active diagnostic codes.

Expected Result:

The "Engine Control Alarm Status" indicator illuminated and a 542-3 diagnostic code was activated when the unfiltered engine oil pressure sensor is disconnected.

The "Fault Relay" indicator illuminated and a 100-3 diagnostic code was activated when the filtered engine oil pressure sensor is disconnected. The engine was shut down.

Results:

• OK - The indicators, diagnostic codes, and shutdown were activated according to the "Expected Result". The outputs for the status indicators seem to be operating correctly at this time. The original problem seems to be resolved.

  Repair: The original diagnostic code was probably caused by a poor electrical connection.

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

  STOP

• Not OK - The "Engine Control Alarm Status" indicator and/or the "Fault Relay" indicator did not illuminate normally when the sensors were disconnected. A 323-3 diagnostic code and/or a 324-3 diagnostic code was generated. There is a problem with the output for the status indicators. The "542-3" and the "100-3" diagnostic codes were generated. The engine was shut down. Proceed to Test Step 4.

Test Step 4. Measure the Voltage of the Suspect Indicator at the P2 Connector

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Illustration 3	g01341999
Typical terminal box (3) Ground strap for the ECM (4) P2 connector (P2-28) Run Relay (P2-29) Crank Terminate Relay (P2-30) Fault Relay (P2-31) Engine Control Alarm Status

1. Insert a 7X-1710 Multimeter Probe into the suspect control terminal in the P2 connector.

2. Connect the positive lead of a voltmeter to the end of the 7X-1710 Multimeter Probe. Connect the voltmeter's negative lead to ground strap (3).

3. Note the voltage that is displayed on the voltmeter.

4. If the customer has equipment for the status indicators, disconnect one wire from the suspect indicator. Be sure to disconnect the wire that comes from the ECM.

5. Insulate the end of the wire with electrical tape in order to ensure that the wire does not create a short circuit.

6. Note the voltage that is displayed on the voltmeter.

Expected Result:

Before the suspect indicator was disconnected, voltage was displayed on the voltmeter. After the suspect indicator was disconnected, the voltmeter displayed approximately zero volts.

Results:

• Yes - Before the suspect indicator was disconnected, voltage was displayed on the voltmeter. After the suspect indicator was disconnected, the voltmeter displayed approximately zero volts. There is a problem in the customer's equipment.

  Repair: The problem could be caused by a poor electrical connection, a wire, or a component in the customer's equipment.

  Set the engine control to the OFF/RESET mode. Switch the 35 amp circuit breaker OFF.

  Thoroughly inspect all wiring and all connectors in the customer's equipment. Refer to Troubleshooting, "Electrical Connectors - Inspect".

  If you suspect that the indicator has an internal short circuit, temporarily install a known good indicator for the suspect indicator. Test the indicator. Verify that the problem is resolved.

  Make the necessary repairs, when possible. Replace parts, if necessary.

  STOP

• No - Before the suspect indicator was disconnected, voltage was displayed on the voltmeter. After the suspect indicator was disconnected, the voltage was still displayed on the voltmeter. Proceed to Test Step 5.

Test Step 5. Check the ECM

1. Disconnect the voltmeter leads and remove the 7X-1710 Multimeter Probe from the P2 connector.

2. Use a 151-6320 Wire Removal Tool to remove the suspect terminal from the ECM P2 connector.

3. Insulate the terminal with electrical tape in order to ensure that the terminal does not create a short circuit.

4. Fabricate a jumper wire with Deutsch terminals on the ends. Insert one end of the jumper wire into the open terminal of the P2 connector.

5. Connect a voltmeter lead to the end of the jumper wire that is not inserted into the connector.

6. Connect the other lead of the voltmeter to the ground strap for the ECM.

7. Observe the voltage reading on the voltmeter.

Expected Result:

The voltmeter displays approximately zero volts.

Results:

• The voltage is approximately zero - After the suspect terminal was removed from connector P2, the reading on the voltmeter was approximately zero. There is a problem with a connection and/or the wiring between the customer's equipment and the ECM.

  Repair: Perform the following procedure:

  1. Disconnect the voltmeter leads.

  2. Use a 151-6320 Wire Removal Tool to remove the jumper wire from the ECM P2 connector.

  3. Insert the terminal for the output wire into the P2 connector. Pull on the wire in order to verify that the terminal is fully inserted into the connector.

     Repair the connection and/or the wiring, when possible. Replace parts, if necessary.

  STOP

• The voltage remained - After the suspect terminal was removed from the P2 connector, voltage was still displayed on the voltmeter. There may be a problem with the ECM.

  Repair: Temporarily install a new ECM. Refer to Troubleshooting, "ECM - Replace".

  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, "ECM - Replace".

  STOP