3176C, 3196 and 3406E Engines for Caterpillar Built Machines Caterpillar

The ground level shutdown switch provides the ability to shut down the engine. The Electronic Control Module (ECM) remains active and the Caterpillar Electronic Technician (Cat ET) can be used to communicate with the ECM. The ground level shutdown switch must be returned to the RUN position and the keyswitch must be cycled to the OFF/RESET position before the ECM will allow the engine to start.

To shut down the engine, lift the red cover guard and toggle the switch to the SHUTDOWN position. The ECM reads the switch position. If the engine is running, the ECM disables the fuel injection. The ECM will not allow the engine to start if the engine is not running.

Normally, the voltage at P1:40 (Ground Level Shutdown Switch (N/O)) is 11.5 ± 0.5 VDC with the switch in the RUN position. The voltage at P1:23 (Ground Level Shutdown (N/C)) is less than 0.5 VDC with the switch in the RUN position.

Illustration 1	g01007938
Schematic

Illustration 2	g01007927
P1 ECM connector

Test Step 1. Check for Connector Damage

1. Turn the keyswitch to the OFF/RESET position.

2. Check the connectors and wiring for the following problems: damage, corrosion, abrasion and incorrect attachment.

Expected Result:

The connectors and the wiring are free of the following problems: damage, corrosion, abrasion and incorrect attachment.

Results:

• OK - Proceed to Test Step 2.

• Not OK -

  Repair: Repair the connectors or wiring and/or replace the connectors or wiring.

  STOP

Test Step 2. Check the Switch on Cat ET

1. Connect Cat ET to the service tool connector.

2. Turn the keyswitch to the ON position.

3. Operate the ground level shutdown switch. Observe the status for the ground level shutdown switch on Cat ET.

4. Turn the keyswitch to the OFF/RESET position.

Expected Result:

The status of the switchis "ON" with the switch in the SHUTDOWN position. The status is "OFF" when the switch is in the RUN position.

Results:

• OK - The switch is operating normally.STOP

• Not OK - Proceed to Test Step 3.

Test Step 3. Short the Wires at the Switch

Record the switch wiring before removing the wires.

1. Disconnect the wires from the ground level shutdown switch.

2. Install a jumper wire between P700:3 (Ground Level Shutdown Switch (N/O)) and P700:2 (Digital Return). Leave P700:1 (Ground Level Shutdown Switch (N/O)) open.

3. Turn the keyswitch to the ON position.

4. Observe the status of the ground level shutdown switch on Cat ET. The status of the switch should be "OFF".

5. Disconnect the wires from P700:3 (Ground Level Shutdown Switch (N/C)) and P700:2 (Digital Return).

6. Install a jumper wire between P700:1 (Ground Level Shutdown Switch (N/O)) and P700:2 (Digital Return).

7. Turn the keyswitch to the OFF/RESET position.

8. Turn the keyswitch to the ON position.

9. Observe the status of the ground level shutdown switch on Cat ET. The status of the switch should be "ON".

10. Remove the wire short.

Expected Result:

The status of the ground level shutdown switch changes accordingly as you short the terminals of the P700 ground level shutdown switch connector.

Results:

• OK - The problem is not with the harness and/or in the ECM.

  Repair: Temporarily connect a new switch. Verify that the new switch solves the problem before you permanently install the new switch.

  STOP

• Not OK - There is a problem in the harness and/or the ECM. Proceed to Test Step 4.

Test Step 4. Check for a Short Circuit in the Wiring Harness

1. Turn the keyswitch to the OFF/RESET position.

2. Disconnect the J1/P1 ECM connector and the J700/P700 ground level shutdown switch connector.

3. Measure the resistance between P1:40 (Ground Level Shutdown Switch (N/O)) and P1:5 (Digital Return).

4. Measure the resistance between P1:23 (Ground Level Shutdown Switch (N/C)) and P1:5 (Digital Return).

5. Measure the resistance between P1:40 (Ground Level Shutdown Switch (N/O)) and P1:23 (Ground Level Shutdown Switch (N/C)).

6. Measure the resistance between P1:23 (Ground Level Shutdown Switch (N/C)) and engine ground.

7. Measure the resistance between P1:40 (Ground Level Shutdown Switch (N/O)) and engine ground.

Expected Result:

The resistance is greater than 20,000 Ohms for each measurement.

Results:

• OK - Proceed to Test Step 5.

• Not OK - There is a short in the harness between the switch and the ECM.

  Repair: Repair the connectors or wiring and/or replace the connectors or wiring.

  STOP

Test Step 5. Check the Resistance Through the Harness

1. Install a jumper wire between P700:1 (Ground Level Shutdown Switch (N/O)) and P700:2 (Digital Return) at the ground level shutdown switch.

2. Measure the resistance between P1:40 (Ground Level Shutdown Switch (N/O)) and P1:5 (Digital Return).

3. Install a jumper wire between P700:3 (Ground Level Shutdown Switch (N/C)) and P700:2 (Digital Return) at the ground level shutdown switch.

4. Measure the resistance between P1:23 (Ground Level Shutdown Switch (N/C)) and P1:5 (Digital Return).

5. Remove the wire short and reconnect the J1/P1 ECM connector and the J700/P700 ground level shutdown switch connector.

Expected Result:

The resistance is less than 10 Ohms for each measurement.

Results:

• OK - The resistance is within acceptable limits. Proceed to Test Step 6.

• Not OK - There is an open or excessive resistance in the harness.

  Repair: Repair the connectors or wiring and/or replace the connectors or wiring.

  STOP

Test Step 6. Short the Switch Inputs at the ECM

1. Remove the wires from P1:40 (Ground Level Shutdown Switch (N/O)), P1:23 (Ground Level Shutdown Switch (N/C)), and P1:5 (Digital Return). Use a 121-9587 Wire Removal Tool .

2. Insert a jumper wire with sockets on each end between P1:23 (Ground Level Shutdown Switch (N/C)) and P1:5 (Digital Return).

3. Turn the keyswitch to the ON position.

   Note: The digital return will no longer be connected to the other sensors and switches. Additional diagnostic codes will be generated. Clear the codes after you complete this test.

4. Observe the status of the ground level shutdown switch on Cat ET. The status of the switch should be "OFF".

5. Turn the keyswitch to the OFF/RESET position.

6. Remove the jumper wire.

7. Install the jumper wire between P1:40 (Ground Level Shutdown Switch (N/O)) and P1:5 (Digital Return).

8. Turn the keyswitch to the ON position.

9. Observe the status of the ground level shutdown switch on Cat ET. The status of the switch should be "ON".

10. Turn the keyswitch to the OFF/RESET position.

11. Remove the wire short.

Expected Result:

The status of the ground level shutdown switch changes accordingly as you short the terminals of the P1 ECM connector.

Results:

• OK - The harness is faulty.

  Repair: Repair the connectors or wiring and/or replace the connectors or wiring.

  STOP

• Not OK -

  Repair: Replace the ECM. Refer to Troubleshooting, "Replacing the ECM with a New ECM".

  STOP