IT28G Integrated Toolcarrier and 924G, 924GZ and 928G Wheel Loaders Caterpillar

Illustration 1	g00987048

This diagnostic code is recorded when the ECM determines that the signal from the shift lever is invalid.

Test Step 1. CHECK THE SHIFT LEVER SIGNAL

Use Cat ET for this test.

1. Disconnect the FNR switch harness 4 pin C-C50 connector from the shift lever.

2. Connect a jumper wire from pin 3 to pin 4 on the shifter 4 pin connector.

3. Connect Cat Electronic Technician (Cat ET) to the machine.

4. Turn on the disconnect switch and the keyswitch.

5. Select the power train ECM.

6. Go to Cat ET status screen 4.

7. Move the shift lever through all possible positions. Observe the status of the "Shift Lever Position" on the ET screen.

Expected Result:

The status of the shift lever position changes properly.

Results:

• Status changes properly - The status of the shift lever position changes properly. The diagnostic code does not exist at this time. Proceed to Test Step 5.

• Status always invalid - The status on Cat ET is "DATA FAULT" in all positions of the shifter. Proceed to Test Step 2.

• Status is invalid in one position - The status on Cat ET is "DATA FAULT" in a particular position. Proceed to Test Step 3.

Test Step 2. CHECK FOR POWER AND GROUND AT THE SHIFTER

Use a calibrated digital multi-meter with spoon probes for these tests.

1. At the shifter 6 pin connector, connect the positive (red) multimeter lead to wire 110-GN(Green).

2. Connect the negative (black) multimeter lead to wire 200-BK(Black).

3. Measure the voltage between the two wires.

Expected Result:

The voltage is system voltage.

Results:

• OK - The voltage is system voltage. Proceed to Test Step 3.

• NOT OK - The voltage is not system voltage. The wiring to the shifter may have failed.

  Repair: Check the fuse for wire 110-GN(Green).

  If the fuse is bad, replace the fuse.

  If the fuse is good, the wiring may have failed. Repair or replace the wiring between the fuse and the shifter or between the shifter and ground.

  STOP

Test Step 3. CHECK THE SHIFTER HARNESS AND ECM

Reference: The shifter schematic

1. The shift lever has three connectors:

   • 8 Pin

   • 6 Pin

   • 4 Pin

2. At the shifter, disconnect the 6-pin C-C52 harness connector.

   The eight pin harness connector remains connected to the shifter 8 pin connector.

   Pins 3 and 4 of the shifter 4 pin connector remains jumpered.

3. Check the voltage at each of the shift lever inputs.

   If a particular position is already suspect, begin with the wires for that position.

Expected Result:

All voltage is 0.

A reading of 0 V indicates that the wire is correctly grounded by the transmission ECM.

If the voltage reading is not 0 V at a specific switch position, the transmission ECM has failed to ground the wire.

Results:

• OK - All voltage is 0. The ECM and harness are working correctly.

  Repair: Replace the shifter.

  STOP

• NOT OK - A voltage is not 0. The wiring or the ECM may have failed. Proceed to Test Step 4.

Test Step 4. CHECK THE ECM

1. Open the machine service disconnect switch.

2. Based on the information in Table 2 remove the corresponding wires from the machine ECM harness connectors "C-C12" and "C-C13". After removing all of the wires shown in Table 2, place DT sockets into the connectors and wire the sockets. This action will allow the wires to be individually grounded. Be sure that the wires cannot accidentally touch frame ground.

3. Close the machine service disconnect switch.

4. Power up the machine with the key in the run position.

5. Connect and start up Cat ET.

6. Connect the two wires from the machine ECM harness connectors to frame ground to simulate each position of the shifter.

   If a particular position is already suspect, begin with the wires for that position.

   Reference: See the following:

   • The shifter schematic

   • Table 1

   • Table 2

7. Monitor the status of the shifter with Cat ET.

Expected Result:

As each combination of contacts is grounded, Cat ET displays the corresponding shifter position.

Results:

• OK - As each combination of contacts is grounded, Cat ET displays the corresponding shifter position. The ECM is working properly. The harness may have failed.

  Repair: Repair or replace the harness.

  STOP

• NOT OK - As each combination of contacts is grounded, Cat ET does not display the corresponding shifter position. The ECM may have failed.

  Repair: Clean the contacts for the ECM harness connectors.

  ECM failure is unlikely. Exit this procedure and perform this procedure again. If the problem remains, contact your Technical Communicator.

  STOP

Test Step 5. VERIFY REMOTE FNR SWITCH FUNCTIONALITY

1. Place steering column shift lever in Neutral and First Gear.

2. Remove the jumper wire between pin 3 and pin 4 of the shifter 4 pin connector.

3. Connect the four pin receptacle, connector "C-C50" from the cab harness onto the shifter 4 pin plug.

   This action will enable the remote FNR switch circuit for the shift handle.

4. Insure that the pins and sockets are seated properly and that the connector mates correctly.

5. Place the remote FNR switch in the FORWARD position.

6. Verify that Cat ET shows "F1" as desired gear.

7. Place the remote FNR switch in the REVERSE position.

8. Verify that Cat ET shows "R1" as desired gear.

Expected Result:

As each combination is switched, Cat ET displays the corresponding gear and direction.

Results:

• Status changes properly - As each combination is switched, Cat ET displays the corresponding gear and direction. Monitor the machine. If the problem occurs, repeat the entire test procedure again.

  STOP

• Status invalid - Cat ET displays "DATA FAULT" in either a particular position or all positions. Proceed to Test Step 6 .

Test Step 6. CHECK REMOTE FNR HARNESS

1. Ensure that the steering column shift lever is in Neutral and First Gear.

2. Assure that the cab harness 4 pin receptacle connector C-C50 is connected to the shifter 4 pin plug.

3. Disconnect the six pin connector that goes to the remote FNR switch assembly.

4. On the cab harness connector "C-C23", place a jumper wire from pin 1 202-BK(Black) to pin 4 G787-GN(Green).

5. Verify that Cat ET shows "F1" as the desired gear.

6. Move the jumper wire connection from pin 1 202-BK(Black) to pin 6 G788-YL(Yellow).

7. Verify that Cat ET shows "R1" as the desired gear.

8. Move the jumper wire connection from pin 1 202-BK(Black) to pin 5 P916-OR(Orange).

9. Verify that Cat ET shows "N1" as the desired gear.

Expected Result:

As each jumper pin combination is checked, Cat ET displays the corresponding gear and direction.

Results:

• Status changes properly - As each jumper pin combination is checked, Cat ET displays the corresponding gear and direction. The harness from the remote FNR switch assembly to the ECM is working correctly.

  Repair: Replace the remote FNR switch assembly.

  STOP

• Status always invalid - Cat ET displays "DATA FAULT" no matter which wire is jumpered to pin 1. The common signal pin 1 202-BK(Black) may have lost connection to machine ground. The harness may have failed.

  Repair: Replace or repair the harness.

  STOP

• Status invalid when a particular wire is jumpered - Cat ET displays "DATA FAULT" when a particular wire is jumped to pin 1. The wiring harness may have failed.

  Repair: Replace or repair the harness.

  STOP