TH48-E80 Petroleum Transmission Power Train Electronic Control System Caterpillar

Illustration 1	g01186920
Schematic of the Shift Control Circuit from the 40 Pin Connector to the ECM

This diagnostic code is recorded when the ECM reads erratic data from the transmission shift control.

The possible causes of this diagnostic code are listed:

• A shorted harness or an open harness

• The transmission shift control has failed.

• The ECM has failed.

Note: Ensure that the CID 0702 FMI 02 for the controller is active.

Test Step 1. CHECK THE BATTERY VOLTAGE.

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

2. At the 40 pin connector, measure the voltage from contact 6 to frame ground.

Expected Result:

The voltage should be approximately battery voltage.

Results:

• OK - The voltage that is measured is approximately battery voltage. Proceed to test step 2.

• NOT OK - The voltage that is measured is not approximately battery voltage.

  Repair: Repair the harness or replace the harness. Verify that the repair corrects the problem.

  STOP

Test Step 2. CHECK THE GROUND CIRCUIT.

1. The key start switch and the disconnect switch remain in the OFF position.

2. At the connector for the sensor, measure the resistance from contact 2 to frame ground.

Expected Result:

The resistance should be less than 5 ohms.

Results:

• OK - The resistance is less than 5 ohms. Proceed to test step 3.

• NOT OK - The resistance is greater than 5 ohms.

  Repair: There is an open in the ground circuit. Repair the harness or replace the harness. Verify that the repair corrects the problem.

  STOP

Test Step 3. CHECK THE HARNESS.

1. Use the Electronic Technician in order to view the status of the contacts for the position sensor. See Troubleshooting, "Using Caterpillar Electronic Technician to Determine Diagnostic Codes".

2. View the ET status screen 9 as the transmission shift control is cycled through the gears. The ground verify (pin 1) should always be grounded. Two additional wires should be grounded in order to indicate the current gear selection. Therefore, three wires are grounded and three wires will be open.

Expected Result:

The display shows the correct indication for each contact.

Results:

• OK - The display shows the correct indication for each contact.

  Repair: The sensor has failed. Replace the sensor. Verify that the sensor corrects the problem.

  Proceed to test step 4.

• NOT OK - The display does NOT show the correct indication for each contact.

  Repair: The problem is in the circuit that did not display a correct indication. Repair the circuit or replace the harness.

  Proceed to test step 4.

Test Step 4. CHECK IF THE DIAGNOSTIC CODE REMAINS.

1. Inspect the contacts and clean the contacts of the harness.

2. Reconnect all harness connectors.

3. Turn the disconnect switch and the key start switch to the ON position.

4. Operate the machine.

5. Stop the machine and engage the parking brake.

6. Observe the status of the diagnostic code.

Expected Result:

The diagnostic code is no longer active.

Results:

• OK - The diagnostic code is no longer present. The diagnostic code does not exist at this time. The initial diagnostic code 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

• NOT OK - The diagnostic code has not been corrected.

  Repair: It is unlikely that the ECM has failed. Exit this procedure and perform this diagnostic code again. If the cause of the diagnostic code is not found, replace the ECM. See Testing and Adjusting, "Electronic Control Module (ECM) - Replace".

  STOP