26SI Series Alternator – MID 122 – CID 0269 – FMI 03

Conditions Which Generate This Code:

This diagnostic code is recorded when the voltage of the sensor supply circuit (T930-WH-18) is above the normal range (nominal 8.3 VDC). Any sensor that is connected to this supply may not operate properly or the sensor may be damaged. If there is not a sensor connected, then this fault can be considered a nuisance fault. The possible causes of this diagnostic code are listed below:

  • The circuit for +V (T930-WH-18) to the sensor is shorted to the battery.

  • The sensor is faulty.

  • The ECM is faulty, however ECM failure is unlikely.

Test Step 1. CHECK THE SUPPLY OUTPUT FOR THE SENSOR.

  1. Disconnect the Product Link Input or Output cable (J2) from the sensor cable for the machine.
  1. Turn the key start switch to the ON position.
  1. Measure the sensor supply output (J2-1) to verify that it is less than 9 VDC when on and less than 4 VDC when off.

Expected Result:

The sensor supply output measures above less than 4 VDC in the off state and less than 9 VDC in the on state.

Results:

  • OK – The voltage is in the required voltage range. The Product Link Sensor Supply and Product Link harness are likely not faulty. The machine harness or the external sensor may be faulty. Proceed to Test Step 3.

  • NOT OK – The voltage is not in the required voltage range. The Product Link cable has a possible short to the battery. Proceed to Test Step 2.

Test Step 2. CHECK THE PRODUCT LINK HARNESS FOR A SHORT TO BATTERY.

  1. Turn the key start switch to the OFF position.
  1. Keep the Product Link Input or Output cable disconnected from the cable for the sensor for the machine.
  1. At the Product Link harness, measure the resistance from sensor supply contact J2-1 (+V) to the Product Link cable J1-1.

Expected Result:

The resistance should be greater than 5000 ohms.

Results:

  • OK – The Product Link harness is correct. Proceed to Test Step 3.

  • NOT OK – There is a short in the Product Link harness J2-1 (T930-WH-18) and a battery source (J1-1).

    Repair: Repair the Product Link harness or replace the Product Link harness.

    STOP

Test Step 3. CHECK THE CABLE FOR THE SENSOR FOR A SHORT TO BATTERY.

  1. Keep the Product Link harness Input or Output cable that is disconnected from the sensor cable for the machine.
  1. At the sensor machine harness, measure the resistance from sensor supply contact J2-1 (+V) to battery power.

Expected Result:

The resistance should be greater than 5000 ohms.

Results:

  • OK – The sensor or the sensor harness are not shorted to the battery. Proceed to Test Step 4.

  • NOT OK – There is a short between the sensor harness “J2-1” (T930-WH-18) and the source for the battery, or the sensor has failed resulting in a short to the battery.

    Repair: Replace the wiring harness or repair the wiring harness.

    STOP

Test Step 4. CHECK IF THE DIAGNOSTIC CODE IS STILL ACTIVE.

  1. Clean the contacts of the harness connectors.
  1. Reconnect all harness connectors.
  1. Turn the key start switch to the ON position.
  1. Operate the machine.
  1. Determine if CID 0269 FMI 03 diagnostic code is present by using Cat ET.

Expected Result:

The “CID 0269 FMI 03” diagnostic code is present.

Results:

  • OK – The problem has not been corrected. However, ECM failure is unlikely.

    Repair: Perform this diagnostic test procedure again. If the cause of the diagnostic code is not found, replace the Product Link ECM. Before replacing the Product Link, contact your Caterpillar Technical Communicator. Refer to Systems Operation, Troubleshooting, Testing and Adjusting, “Electronic Control Module (ECM) – Replace”.

    STOP

  • NOT OK – The diagnostic code is not present. The problem does not exist at this time. The initial problem was probably caused by a poor electrical connection or a short at one of the harness connectors that was disconnected and reconnected. Resume normal machine operation.STOP
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