TA19 and TA22 Transmissions Power Train Electronic Control System Caterpillar

Illustration 1	g01343159
Connections for the 10 volt sensor supply

The sensor supply is a power supply that is internal to the ECM. The sensor supply provides 10 VDC in order to operate the sensors.

This diagnostic code will be recorded when the Transmission ECM reads the voltage for the circuit of the sensor supply as being below normal.

The possible causes of the diagnostic code are listed:

• 10 VDC is shorted to ground between the sensor and the ECM.

• The ECM has failed. This is unlikely.

System Response:

The results of this diagnostic code are listed:

• All of the associated sensors will also log diagnostic codes.

Test Step 1. CHECK THE SENSOR.

1. Ensure that the diagnostic code of SPN 1542 FMI 1 is present. The diagnostic code should be active.

2. Disconnect the machine harness from all of the sensors in the circuit.

Expected Result:

The diagnostic code is NO longer active.

Results:

• OK - The diagnostic code is NO longer active. One of the sensors have failed.

  Repair: Reconnect the sensors one at a time until the diagnostic code becomes active. Replace the sensor that causes the active diagnostic code.

  STOP

• NOT OK - The diagnostic code remains active. The sensors are NOT causing the diagnostic code. Proceed to Test Step 2.

Test Step 2. CHECK FOR A SHORT TO GROUND.

1. The sensors remain disconnected from the machine harness.

2. Turn the disconnect switch and the key start switch to the OFF position.

3. Disconnect the machine harness from the ECM.

4. At the ECM, measure the resistance between the contact of the sensor supply voltage (J1-13) and frame ground.

Expected Result:

The resistance is greater than 5000 ohms.

Results:

• OK - The resistance that is measured is greater than 5000 ohms. The harness circuit is correct. The ECM has failed.

  Repair: It is unlikely that the ECM has failed. Exit this procedure. Perform the diagnostic code procedure for SPN 1542 FMI 1 again. If the cause of the diagnostic code is NOT found, replace the ECM . See Testing and Adjusting, "Electronic Control Module (ECM) - Replace".

  STOP

• NOT OK - The resistance that is measured is less than 5000 ohms. The machine harness has failed. There is a short between frame ground and the contact for the sensor supply voltage in the machine harness.

  Repair: Repair the machine harness or replace the machine harness.

  STOP