TA19 and TA22 Transmissions Power Train Electronic Control System Caterpillar

Illustration 1	g01343159
Connections of 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 above normal.

The possible causes of the diagnostic code are listed:

• The +10 VDC is shorted to the +battery circuit.

• The ECM has failed. This is unlikely.

Test Step 1. CHECK FOR SHORT TO THE +BATTERY CIRCUIT

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

2. Disconnect the machine harness from the ECM.

3. At the machine harness connectors for the ECM, measure the resistance between the +battery contact (J2-1) and the contact for the sensor supply voltage (J1-13).

Expected Result:

The resistance that is measured should be greater than 5000 ohms.

Results:

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

  Repair: It is unlikely that the ECM has failed. Perform the Test Step 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 measures less than 5000 ohms. The machine harness has failed. There is a short between the +battery circuit and the circuit for the sensor power supply in the machine harness.

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

  STOP