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 FMI 03 diagnostic code is activated by the ECM when none of the switch input circuits is grounded.

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

• The switch has failed.

• Open or bad connection in the common ground circuit.

• Open or bad connection in a switch input circuit.

• Machine ECM failure. 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. DETERMINE WHICH CIRCUIT IS NOT CORRECT

This step will determine which one of the five switch inputs to the ECM is causing the problem. If the suspected problem circuit is known, proceed to the next test step.

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

2. While observing the active CID 2705 FMI 03 diagnostic code, move the Throttle Switch to each of the three positions. At each switch position, determine if the CID 2705 FMI 03 diagnostic code is active.

Expected Result:

The CID 2705 FMI 03 diagnostic code is active in one or all of the switch positions.

Results:

• YES - The CID 2705 FMI 03 diagnostic code is active in one of the switch positions. Record the circuit that is causing the problem. If the CID 2705 FMI 03 activates only in one of the switch positions: this event indicates that either the switch has failed, or the selected switch input circuit is open. Proceed to Test Step 3.

• YES - The CID 2705 FMI 03 diagnostic code is active in all of the switch positions. This condition indicates that there is either a problem with the switch, a harness connector, or with the common ground circuit. Proceed to Test Step 2.

• NO - The CID 2705 FMI 03 diagnostic code is not active in any of the switch positions.

  Repair: If the CID 2705 FMI 03 diagnostic code was active and is no longer active, turn the key switch and the disconnect switch OFF. Refer to the complete machine Electrical System Schematic. Disconnect and inspect all of the connectors that are in the switch input circuits. Ensure that all connections are clean, secure and in good condition.

  Proceed to Test Step 5.

Test Step 2. CHECK THE SWITCH COMMON GROUND CIRCUIT FOR AN OPEN

An open common ground switch circuit will result in the CID 2705 FMI 03 becoming active when the switch is in any position. If the CID 2705 FMI 03 diagnostic code is not active in all switch positions, proceed to the next test step.

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

2. Disconnect the machine harness connector from the switch module.

3. At the machine harness connector for the switch module, measure the resistance from switch common ground contact 2 (wire J766-PU) and 5 (wire J766-PU).

4. While observing the multimeter resistance measurement, wiggle the machine harness connector for the switch. Gently pull on the wires and move the wires around.

Expected Result:

The resistance measurement is less than 5 ohms at all times during the manipulation of the harness.

Results:

• YES - The resistance measurement is less than 5 ohms. The switch common ground circuit is correct. Proceed to Test Step 3.

• NO - The resistance measurement is greater than 5 ohms. There is an open or a bad connection in the switch common ground circuit (wire J766-PU).

  Repair: Resistances greater than 5 ohms but less than 5000 ohms: This condition indicates a point or splice connection in the ground circuit is not open, but is not a good connection. Resistances greater than 5000 ohms:This condition indicates that a wire is open, or not connected. Refer to the complete machine Electrical System Schematic. Start at the sensor and work back to the ECM connection. Check all of the connectors and wires that are in the switch circuit for continuity. Ensure that all of the connections are clean, locked into the connector housing and in good condition. Repair the machine harness or replace the machine harness.Repair or replace the machine harness.

  STOP

Test Step 3. CHECK THE SWITCH

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

1. At the connector for the switch module, place the switch in position "A". Check resistance from common ground contact #1 to each of the five switch input contacts individually. Check continuity from the common ground 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 common ground contact and each of the switch contacts in each switch position is correct according to the switch status table.

Results:

• YES - The continuity between the common contact and each of the switch contacts in each switch position is correct according to the switch status table. The operation of the Throttle Switch is correct. Proceed to Test Step 4.

• NO - The continuity from the common ground contact to each of 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 in order 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.

  STOP

Test Step 4. CHECK THE SWITCH CIRCUIT FOR AN OPEN

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

1. At the switch harness connector, place a jumper wire from the suspect faulty switch input circuit to one of the other switch input circuits.

2. Disconnect the machine harness connector J2 from the Machine ECM.

3. At the harness connector J2 for the ECM, measure the resistance between the same two switch input circuits that are connected by the jumper wire.

4. While observing the resistance measurement of the circuits, gently wiggle the machine harness near the ECM connectors and near the switch connector.

Expected Result:

The resistance measurement is less than 5 ohms at all times during the manipulation of the harness.

Results:

• YES - Resistance is less than 5 ohms at all times, while manipulating the harness. The resistance measurement is not indicating that there is an open or a poor connection in the switch signal circuits. Proceed to Test Step 5.

• NO - Resistances greater than 5 ohms during the movement of the harness. There is an open or a bad connection in the signal circuit.

  Repair: Resistances greater than 5 ohms but less than 5000 ohms: This condition indicates a point or splice connection in the ground circuit is not open, but is not a good connection. Resistances greater than 5000 ohms:This condition indicates that a wire is open, or not connected. Refer to the complete machine Electrical System Schematic. Start at the sensor and work back to the ECM connection. Check all of the connectors and wires that are in the switch circuit for continuity. Ensure that all of the connections are clean, locked into the connector housing and in good condition. Repair the machine harness or replace the machine harness.Repair the machine harness or replace the machine harness.

  STOP

Test Step 5. 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 sensor circuit.

3. Reconnect all harness connectors. Make sure that the connectors are fully seated and the clips for each connector are securely 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 03 diagnostic code.

Expected Result:

The diagnostic code is not active.

Results:

• YES - The 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 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 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 the ECM must be replaced, refer to Testing and Adjusting, "Electronic Control Module (ECM) - Replace".

  STOP