IT12F, IT14F, IT18F, IT24F and IT28F Integrated Toolcarriers and 910F, 918F, 924F and 928F Wheel Loaders Power Train Electronic Control System Caterpillar

Illustration 1	g00620218

Note: Before troubleshooting, move the transmission control through all positions. Ensure that the fault is on hold.

Test Step 1. CHECK FOR THE + BATTERY AT THE NEUTRALIZER SWITCH.

Note: Use the 7X-1710 Multimeter Probe to measure voltage in this step.

1. Turn the disconnect switch and the keyswitch to the ON position.

2. Measure the + battery.

3. At the neutralizer switch, measure the voltage at 126-PK-18.

Expected Result:

The measured voltage should be approximately +battery.

Results:

• YES - The measured voltage is approximately +battery. Proceed to test step 2.

• NO - The measured voltage is NOT approximately +battery. The wire 126-PK-18 has failed or the fuse is blown.

  Repair: Repair the wire or replace the fuse.

  Stop.

Test Step 2. CHECK THE TRANSMISSION NEUTRALIZER SWITCH.

1. The disconnect switch and the keyswitch remain in the ON position.

2. At the neutralizer switch, measure the voltage at 720-PU-18. Press the brake pedal and release the brake pedal.

Expected Result:

When the brake pedal is pressed, NO voltage should be measured. When the brake pedal is NOT pressed, the measured voltage should be approximately +battery.

Results:

• YES - When the brake pedal is pressed, NO voltage is measured. When the brake pedal is NOT pressed, the measured voltage is approximately +battery. The switch is correct. Proceed to test step 3.

• NO - When the brake pedal is pressed the voltage is measured. When the brake pedal is not pressed, the measured voltage is NOT approximately +battery. The neutralizer switch has failed.

  Repair: Replace the neutralizer switch.

  Stop.

Test Step 3. CHECK THE NEUTRALIZER CIRCUIT.

Note: Use the 7X-1710 Multimeter Probe to measure voltage in this step.

1. The disconnect switch and the keyswitch remain in the ON position.

2. Measure the voltage across the transmission control 720-PU-18, and the ground contact of the neutralizer circuit.

Expected Result:

The measured voltage should be approximately +battery.

Results:

• YES - The measured voltage is approximately +battery. The neutralizer circuit is correct. Proceed to test step 4.

• NO - The measured voltage is NOT approximately +battery. The neutralizer circuit has failed.

  Repair: Repair the harness or replace the harness.

  Stop.

Test Step 4. CHECK THE HARNESS FOR A SHORT.

Note: The neutralizer switch must NOT be activated during the check.

1. Turn the keyswitch and the disconnect switch to the OFF position.

2. Disconnect the transmission control from the machine harness.

3. Disconnect the transmission ECM from the machine harness.

4. At the machine harness connector, measure the resistance between contact 12 and contact 18 and all of the other contacts.

Expected Result:

All of the measured resistances should be greater than 5,000 ohms.

Results:

• YES - All of the measured resistances are greater than 5,000 ohms. Proceed to Test Step 5.

• NO - One or more of the measured resistances is less than 5,000 ohms. The harness has a short between the wires with low resistance measurements.

  Repair: Repair the harness or replace the harness.

  Stop.

Test Step 5. CHECK THE HARNESS FOR AN OPEN.

1. The disconnect switch and the keyswitch remain in the OFF position.

2. The machine harness remains disconnected from the transmission control and the transmission ECM.

3. At the transmission control's connector, measure the resistance from 967-BU-18, 965-WH-18 and the ground wire to the corresponding ECM connector's contact 18, contact 12, and contact 2.

Expected Result:

All of the measured resistances should be less than 5,000 ohms.

Results:

• YES - The resistances are less than 5,000 ohms. The sensor is operating properly. Inspect the harness connector and inspect the contacts. Verify that the diagnostic code is present. If the code is present, the transmission electronic control module has failed.

  Repair: It is unlikely that the ECM has failed. Exit this procedure and perform this procedure again. Also, recheck if the diagnostic code is active. If the cause of the diagnostic code is not found, replace the transmission ECM. See Testing and Adjusting, "Electronic Control Module (ECM) - Replace". Clear the diagnostic code. Refer to Systems Operation, "Diagnostic Operation".

  Stop.

• NO - One or more of the measured resistance are greater than 5,000 ohms. The wire or wires with the high resistances are open.

  Repair: Repair the wires or replace the harness.

  Stop.