D6N Track-Type Tractor Caterpillar

Illustration 1	g02722691
The Cab Throttle Switch connections in the Throttle Switch.

This diagnostic code is associated with the Cab Throttle Switch. The switch module is located on the left console in the cab. The switch provides three switch inputs to the machine ECM. The ECM detects the position of the switch when the corresponding switch position input circuit contacts are closed.

During normal operations: one of the switch inputs is connected to 8 v sensor return creating a closed circuit.

The CID 2705 FMI 04 diagnostic code is activated by the ECM when every switch input circuit is grounded at the same time.

The conditions that could cause the ECM to activate this diagnostic code are listed below:

• The switch has failed.

• There is a short to a ground source in one or more of the switch input circuits.

• The ECM has failed. ECM failure is unlikely.

The following table indicates the switch circuits in each switch position.

Note: CAT ET will show the ECM status of the four individual switch inputs.

Note: Switch contacts 2 and 5 are always grounded.

Note: Poor connections may be the cause of a problem in an electrical circuit. Verify that all connections in the circuit are clean, secure and in good condition. If a problem with a connection is found, correct the problem and verify that this diagnostic code is active before performing this procedure.

Note: The following test procedure may cause other diagnostic codes to be activated. Ignore these created diagnostic codes and clear the diagnostic codes when the problem has been corrected.

Test Step 1. CHECK THE SWITCH

1. Turn the key switch disconnect switch and the disconnect switch to the ON position. DO NOT START THE ENGINE.

2. While observing the status of the active CID 2705 FMI 04 diagnostic code, disconnect the machine harness connector from the switch module connector.

Expected Result:

When the machine harness connector for the Throttle Switch is disconnected from the Throttle switch module connector, a CID 2705 FMI 03 diagnostic code becomes active. The CID 2705 FMI 04 diagnostic code is no longer active.

Results:

• YES - The CID 2705 FMI 03 diagnostic code is no longer active. A CID 2705 FMI 04 becomes active when the machine harness connector is disconnected from the switch module connector. This condition indicates that the operation of the Throttle Switch is not correct. Verify that the switch is defective in the next test step. Proceed to Test Step 2.

• NO - The CID 2705 FMI 03 diagnostic code remains active when the machine harness connector is disconnected from the switch module connector. The Throttle Switch is not causing the problem. Proceed to Test Step 3.

Test Step 2. CHECK THE SWITCH OPERATION

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

2. Disconnect the machine harness connector from the Cab Throttle Switch module.

3. At the connector for the switch module, place the switch in "Low"position. Check resistance from 8 v sensor return contacts 2and5to each of the switch input contacts. Check continuity from the 8 v sensor return contact to the other switch contacts in this manner, with the switch in every possible position. Refer to the switch status table at the beginning of this procedure for the correct continuity.

Expected Result:

The continuity between the 8 v sensor return contact and the switch contacts in each switch positions is correct according to the switch status table.

Results:

• YES - The continuity between the 8 v sensor return contact and the contacts in each switch position is correct according to the switch status table. The operation of the Throttle Switch is correct. Go to Test Step 3.

• NO - The continuity from the 8 v sensor return contact to the possible switch contacts is not correct according to the switch status table. The operation of the Throttle Switch is not correct.

  Repair: Repeat this test step to verify that the Throttle Switch operation is not correct for the suspected faulty circuit. If the switch operation is not correct, replace the Throttle Switch / Bidirectional Shift Selection Switch module.After the module is replaced, verify that the new section for the Throttle Switch is operating correctly before operating the machine.

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Test Step 3. CHECK THE SWITCH INPUT CIRCUITS FOR A SHORT

The key switch and the disconnect switch remain in the OFF position. The machine harness remains disconnected from the switch.

1. Disconnect the machine harness connectors J1 and J2 from the ECM.

2. At the machine harness connector J1 for the ECM, measure the resistance between switch input contact J1-45 (wire J766-PU) and frame ground. Measure the resistance between switch input contact J1-45 (wire J766-PU) and switch inputJ2(wireF715-PU) .

3. Repeat the procedure in the previous test step for each of the other three switch input contacts at J2-29, J2-30, andJ2-31 .

Expected Result:

Each resistance measurement is greater than 5000 ohms.

Results:

• OK - Each resistance measurement is greater than 5000 ohms. The switch input circuits are not shorted to ground or to another circuit in the machine harness. Proceed to Test Step 4.

• NOT OK - One or more of the resistance measurements is less than 5000 ohms. There is a short to ground or to another circuit in the machine harness.

  Repair: The input circuit that checks the low resistance to frame ground or to another circuit is causing the problem.Refer to the complete machine Electrical System Schematic. Check all of the connectors that are in the defective input circuit. Ensure that all connections are clean, secure and in good condition.For information on testing for short circuits and finding short circuits, refer to Testing and Adjusting, "Wiring Harness (Short Circuit) - Test". Repair the machine harness or replace machine harness.

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Test Step 4. CHECK THE STATUS OF THE DIAGNOSTIC CODE

1. Inspect the harness connectors and clean the contacts of the harness connectors that are in the affected circuit. Check the wires for damage to the insulation that can be caused by excessive heat, battery acid, or chafing.

2. Perform a 45 N (10 lb) pull test on each of the wires that are associated with the circuits.

3. Reconnect all harness connectors. Make sure that the connectors are fully seated and the clips for each connector are fastened.

4. Turn the disconnect switch and the key start switch to the ON position. DO NOT START THE ENGINE.

5. Check the status of the CID 2705 FMI 04 diagnostic code.

Expected Result:

The CID 2705 FMI 04 diagnostic code is not active.

Results:

• OK - The CID 2705 FMI 04 diagnostic code is not active. The diagnostic code does not exist at this time. The initial diagnostic code was probably caused by a poor connection at one of the connectors that was disconnected and reconnected. Resume normal operation.STOP

• NO - The CID 2705 FMI 04 diagnostic code is active. The diagnostic code has not been corrected.

  Repair: If the problem has not been corrected, Use the Caterpillar Electronic Technician (Cat ET) service tool, if available, in order to perform a "Wiggle Test" on the sensor circuit in the machine wiring harness. The wiggle test can detect momentary or intermittent shorts or opens in the machine wiring harness.If all possible causes of the problem have been investigated and no problem can be found, the ECM could be causing the problem.Prior to replacing an ECM, always contact your dealership Technical Communicator for possible consultation with Caterpillar. If ECM must be replaced, refer to Testing and Adjusting, "Electronic Control Module (ECM) - Replace".

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