3126B Petroleum Engine Caterpillar

The Electronic Control Module (ECM) is the computer that controls the Caterpillar engine. The personality module contains the software that controls the operation of the computer (ECM).

The personality module software is the instructions that are used by the ECM to control the engine. For this reason, updating the personality module to a different version may affect some engine functions.

This procedure covers the following diagnostic codes:

• 253-02 Personality Module mismatch

• 254-12 Electronic Control Module Error

• 268-02 Check Programmable Parameters

Also, use this procedure to troubleshoot the following conditions:

• The integrity of the customer parameters or the system parameters in the ECM is questionable.

• The data for the engine lifetime totals is questionable.

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The connection of any electrical equipment and the disconnection of any electrical equipment may cause an explosion hazard which may result in injury or death. Do not connect any electrical equipment or disconnect any electrical equipment in an explosive atmosphere.

Test Step 1. Check for an Active 254-12 Diagnostic Code

1. Turn the keyswitch to the OFF position.

2. Connect Caterpillar Electronic Technician (ET) to the service tool connector. Check for an active 254-12 diagnostic code.

Expected Result:

The 254-12 code is not active.

Results:

• Not active - A 254-12 code is not active. Proceed to Test Step 2.

• Active - A 254-12 code is active.

  Repair: Replace the ECM. Refer to Troubleshooting, "Replacing the ECM". Verify that the problem is resolved.

  STOP

Test Step 2. Inspect the Electrical Connectors and the Wiring

1. Turn the keyswitch to the OFF position.

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Illustration 1	g01120020
ECM (1) J2/P2 connectors (2) J1/P1 connectors

2. Thoroughly inspect connectors (1) and (2). Inspect the battery connections. Refer to Troubleshooting, "Electrical Connectors - Inspect" for details.

3. Check the allen head screw on the ECM connectors for the proper torque. Refer to Troubleshooting, "Electrical Connectors - Inspect" for the correct torque value.

4. Check the harnesses and the wiring for abrasion and for pinch points.

Expected Result:

All connectors, pins and sockets are completely coupled and/or inserted and the harnesses and wiring are free of corrosion, of abrasion, and of pinch points.

Results:

• OK - The harnesses and the connectors appear to be OK. Proceed to Test Step 3.

• Not OK - The wiring and/or a connector are not OK.

  Repair: Repair the wiring and/or the connectors. Replace parts, if necessary. 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 3. Check for Diagnostic Codes

1. Turn the keyswitch to the ON position.

2. Use Cat ET to check for active diagnostic codes. Observe the "Active Diagnostic" screen on Cat ET. Wait at least 15 seconds so that any codes may become active. Look for these codes:
   • 253-02

   • 254-12

   • 268-02

3. Verify that the engine's configuration parameters are not scrambled.

Expected Result:

None of the above codes are active. The configuration parameters are not scrambled.

Results:

• Active 253-02 code - A 253-02 diagnostic code is active. Proceed to Test Step 4.

• Active 268-02 code - A 268-02 diagnostic code is active. Proceed to Test Step 5.

• Scrambled parameters - The configuration parameters are scrambled. Proceed to Test Step 6.

Test Step 4. Check the Part Number of the Personality Module

1. Turn the keyswitch to the ON position.

2. Use Cat ET to verify that the personality module part number agrees with the original engine arrangement.

Expected Result:

The correct personality module is installed in the ECM.

Results:

• OK - The correct personality module is installed in the ECM.

  Repair: The engine will not start until the 253-02 diagnostic code is cleared. Clearing this code requires factory passwords and resetting the personality module code to zero. Refer to Troubleshooting, "Factory Passwords".Acquire factory passwords. Use Cat ET to reset the personality module code to zero. Clear the 253-02 diagnostic code. Return the engine to service.

  STOP

• Not OK - The correct personality module is not installed in the ECM.

  Repair: Program the ECM with the correct personality module. Refer to Troubleshooting, "Flash Programming". Verify that the repair eliminates the problem.

  STOP

Test Step 5. Determine the Parameters that Require Programming

1. Turn the keyswitch to the ON position.

2. Use Cat ET to verify that the configuration parameters are correct for the engine's application. Refer to Troubleshooting, "System Configuration Parameters".

Expected Result:

The configuration parameters are correct.

Results:

• OK - The configuration parameters are correct.

  Repair: Clear the diagnostic code and return the engine to service.

  STOP

• Not OK - The configuration parameters are not correct.

  Repair: The 268-02 diagnostic code cannot be cleared until all of the parameters are programmed with the correct values. The engine may use a default torque map or the ECM may limit the engine to low idle until this diagnostic code is cleared.Try to program the configuration parameters. Refer to Troubleshooting, "System Configuration Parameters".If the programming is successful, clear the code and return the engine to service.If the parameters cannot be programmed, replace the ECM. Refer to Troubleshooting, "Replacing the ECM". Verify that the repair eliminates the problem.

  STOP

Test Step 6. Review the Parameters and Data

1. Turn the keyswitch to the ON position.

2. Use Cat ET to review the system configuration parameters and the engine lifetime totals.

Expected Result:

The parameters and totals are correct.

Results:

• OK - The parameters and totals are correct.

  Repair: Return the engine to service.

  STOP

• Not OK - The parameters and/or the totals are incorrect.

  Repair: Try to program the suspect parameter or parameters. Refer to Troubleshooting, "System Configuration Parameters".If the programming is successful, clear the code and return the engine to service.If the parameters cannot be programmed, replace the ECM. Refer to Troubleshooting, "Replacing the ECM". Verify that the repair eliminates the problem.

  STOP