3500B Industrial Engines with the ADEM 3 Electronic Control Module Caterpillar

Use this procedure to troubleshoot the electrical system if a problem is suspected with the air shutoff system or if any one of the diagnostic codes in Table 1 is active or easily repeated.

The engine's ECM has the ability to stop the engine by cutting off the inlet air supply in an emergency situation. The ECM activates the air shutoff solenoid in order to close the air shutoff valve. The air shutoff is optional. A programmable parameter needs to be set to "Installed" with Caterpillar Electronic Technician (ET) in order to enable the air shutoff system.

There is a switch at each of the air shutoff valves that is included in a detection circuit that inputs a signal to the engine ECM. The ECM monitors the input from the detection circuit in order to determine if the air shutoff valves are in the closed position. If the circuit indicates that the air shutoff valves are closed, the ECM will generate the E2087 event code.

There are three conditions which cause the engine control to activate the air shutoff solenoid. The first condition occurs when the operator initiates an emergency shutdown. When the emergency shutdown is recognized, fuel is shut off and the air shutoff solenoid is activated. The second condition is for an engine overspeed. The third condition occurs when engine rpm is present and the detection circuit indicates an "ACTIVE" input to the ECM.

The input for the air shutoff switch is "NOT ACTIVE" when the switch circuit indicates an open circuit between terminal P1-55 and terminal P1-56. The input for the air shutoff switch is "ACTIVE" when the switch circuit indicates a closed circuit between terminal P1-55 and terminal P1-56.

Ensure that BOTH of the air shutoff valves are manually reset after activating the air shutoff system in order to start the engine again. Regardless of the reason for activation, the main power to the ECM must be turned OFF for 30 seconds in order to reset the engine control.

Illustration 1	g01264294
Typical schematic

Illustration 2	g01264297
P1 ECM connector (P1-5) Digital return (P1-23) Emergency stop signal 1 (P1-28) Emergency stop signal 2 (P1-55) +Battery from ECM (P1-56) Air shutoff switch

Illustration 3	g01256338
P2 ECM connector (P2-13) Air shutoff

Illustration 4	g01234146
Location of ECM connectors

Illustration 5	g01264298
Machine interface connector (Terminal 4) Air shutoff (Terminal 5) −Battery (Terminal 9) Digital return (Terminal 11) −Battery (Terminal 27) Emergency stop signal (Terminal 31) Left hand air shutoff (Terminal 33) Right hand air shutoff

Test Step 1. Inspect Electrical Connectors and Wiring

1. Turn the breaker for the ECM to the OFF position.

2. Turn the switch that provides power to the keyswitch input for the ECM to the OFF position.

3. Thoroughly inspect the J1/P1 ECM connector and the J2/P2 ECM connector. Inspect all of the connectors that are associated with the circuit.

   Refer to Troubleshooting, "Inspecting Electrical Connectors" for details.

4. Perform a 45 N (10 lb) pull test on each of the wires in the ECM connectors that are associated with the circuit.

5. Check the ECM connector (allen head screw) for the proper torque. Refer to Troubleshooting, "Inspecting Electrical Connectors" for details.

6. Check the harness and wiring for abrasion and for pinch points.

Expected Result:

All connectors, pins and sockets are completely coupled and/or inserted and the harness and wiring are free of corrosion, of abrasion and of pinch points.

Results:

• OK - The connectors and wiring are free of any problems. Proceed to Test Step 2.

• Not OK - The wiring and/or connectors are in need of repair.

  Repair: Repair the wiring and/or connectors or replace the wiring and/or connectors. Refer to Troubleshooting, "Inspecting Electrical Connectors".

  STOP

Test Step 2. Check for "Active" Diagnostic Codes or for "Active" Event Codes

1. Connect Caterpillar Electronic Technician (ET) to the service tool connector.

2. Restore electrical power to the ECM.

3. Monitor the diagnostic codes on Cat ET. Check and record any diagnostic codes.

   Note: Wait at least 30 seconds in order for the diagnostic codes to become active.

4. Determine if a diagnostic code has occurred several times.

   Note: A diagnostic code that is logged several times is an indication of an intermittent problem. Most intermittent problems are the result of a bad connection between a socket and a pin in a connector or a bad connection between a wire and a terminal. The problem may be caused by moisture, corrosion, or wear.

5. Determine if the problem is active and related to one of the following diagnostic codes:
   • 446-5

   • 446-6

   • E2087

   • E2088

Expected Result:

A diagnostic code or an event code is not active.

Results:

• OK - A diagnostic code or an event code is not active.

  Repair: The problem may be intermittent. If the problem is intermittent, refer to Troubleshooting, "Inspecting Electrical Connectors".

  STOP

• Not OK - An E2088 event code is active. The configurable parameter for the air shutoff is set to "Enabled". The configurable parameter "Air Inlet Shutoff Detection" is set to "Not Installed".

  Repair: Go to Troubleshooting, "System Configuration Parameters". Set the parameter for the "Air Inlet Shutoff Detection" to "Installed". Clear the event code.

  STOP

• Not OK - An E2087 event code is active.

  Repair: Verify that the air shutoff valves are in the closed position. If the air shutoff valves are in the closed position, determine the reason for activation of the air shutoff system. After the reason for the air shutoff system's activation has been resolved, remove power from the ECM. Manually open the air shutoff valves. Restore power to the ECM and check for an active E2087 event code. If the air shutoff valves are in the open position and the E2087 event code is active, go to the following test step.

  Proceed to Test Step 3.

• Not OK - A 446-5 event code or a 446-6 diagnostic code is active. Proceed to Test Step 4.

Test Step 3. Check the Detection Circuit for the Air Shutoff System

1. Remove electrical power from the ECM.

2. Disconnect the ECM connector J1/P1.

3. Check continuity between terminals P1-55 and P1-56 on ECM connector P1.

4. Check the continuity between switch terminals at each air shutoff valve.

5. Each continuity check should indicate an open circuit.

6. If a continuity check indicates a short circuit, repair the wiring and/or replace the switch(s).

7. If the E2087 event code is still active after repairing any wiring or repairing any switch, disconnect the wiring from ECM terminals P1-55 and P1-56. Ensure that the wires are not touching engine ground or any other wire in the harness.

8. Reconnect ECM connector J1/P1.

9. Restore electrical power to the ECM.

10. Monitor the diagnostic codes on Cat ET. Check and record any diagnostic codes.

    Note: Wait at least 30 seconds in order for the diagnostic codes to become active.

Expected Result:

The E2087 event code is no longer active.

Results:

• OK - The E2087 event code is no longer active.

  Repair: The problem may be intermittent. If the problem is intermittent, refer to Troubleshooting, "Inspecting Electrical Connectors".

  STOP

• Not OK - The E2087 event code is still active.

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

  STOP

Test Step 4. Check the Status of the Air Shutoff on Cat ET

1. Connect Cat ET to the service tool connector.

2. Turn the breaker for the ECM to the ON position.

3. Turn the switch that provides power to the keyswitch input for the ECM to the ON position.

4. Access the screen for the override for the air shutoff on Cat ET. Activate the override for the air shutoff.

5. Monitor the status of the air shutoff on Cat ET.

6. Deactivate the override for the air shutoff.

Expected Result:

The air shutoff solenoid activates. Cat ET indicates that the air shutoff is "ON".

Results:

• OK - The air shutoff solenoid activates. Cat ET indicates that the air shutoff is "ON".

  Repair: The air shutoff system is operating properly from the ECM to the air shutoff solenoid. The wiring and/or the emergency stop switch that inputs a signal into the ECM may need repair. Check the continuity between ECM terminals P1-23 and P1-05. Check the continuity between ECM terminals P1-28 and P1-05. Check the continuity between the terminals on the emergency stop switch. Repair the wiring and/or replace the switch.

  STOP

• Not OK - The air shutoff solenoid activates. Cat ET does not indicate that the air shutoff is "ON".

  Repair: There is a problem in the wiring between the ECM and the switches at the air shutoff solenoids or there is a problem in the air shutoff switch(s) that indicates that the air shutoff valves are closed. Check the continuity between ECM terminals P1-55 and P1-56. Check the continuity between switch terminals at each air shutoff solenoid. Repair the wiring and/or replace the switch(s).

  STOP

• Not OK - The air shutoff solenoid does not activate. Proceed to Test Step 5.

Test Step 5. Check the Voltage to the Coil of the Air Shutoff Relay

1. Turn the switch that provides power to the keyswitch input for the ECM to the OFF position.

2. Turn the breaker for the ECM to the OFF position.

3. Disconnect wire G971-BR from terminal 3 on the air shutoff relay.

4. Connect a voltmeter between wire G971-BR and engine ground.

5. Turn the breaker for the ECM to the ON position.

6. Turn the switch that provides power to the keyswitch input for the ECM to the ON position.

7. Access the screen for the override for the air shutoff on Cat ET. Activate the override for the air shutoff.

8. Monitor the status of the air shutoff on Cat ET.

9. Deactivate the override for the air shutoff.

10. Turn the switch that provides power to the keyswitch input for the ECM to the OFF position.

11. Turn the breaker for the ECM to the OFF position.

12. Replace all wires to the original configuration.

Expected Result:

The voltage measures 24 ± 3 VDC.

Results:

• OK - The voltage is 24 ± 3 VDC. Proceed to Test Step 6.

• Not OK - The voltage is not 24 ± 3 VDC. Proceed to Test Step 8.

Test Step 6. Check the Output Voltage from the Air Shutoff Relay

1. Disconnect wire G971-BR from terminal 1 on the air shutoff relay.

2. Connect a voltmeter between terminal 1 and engine ground.

3. Turn the breaker for the ECM to the ON position.

4. Turn the switch that provides power to the keyswitch input for the ECM to the ON position.

5. Access the screen for the override for the air shutoff on Cat ET. Activate the override for the air shutoff.

6. Monitor the voltage on the voltmeter.

7. Deactivate the override for the air shutoff.

8. Replace all wires to the original configuration.

Expected Result:

The voltage is 24 ± 3 VDC.

Results:

• OK - The voltage is 24 ± 3 VDC. Proceed to Test Step 7.

• Not OK - The voltage is not 24 ± 3 VDC.

  Repair: Verify that wire 229-BK has continuity from the air shutoff relay to the −Battery. If wire 229-BK is not OK, repair the wire and retest the circuit.If wire 229-BK is OK, verify that 24 ± 3 VDC is present on terminal 2 of the air shutoff relay. If voltage is present on terminal 2 and wire 229-BK is OK, replace the air shutoff relay.If voltage is not present on terminal 2, repair wire 150-OR between the +Battery and the air shutoff relay. Verify that the circuit breaker is not tripped.

  STOP

Test Step 7. Check the Output Voltage at the Solenoid for the Air Shutoff

1. Disconnect the wires to the air shutoff solenoid(s) at the air shutoff solenoid(s).

2. Connect a voltmeter between the wires at the solenoid.

3. Access the screen for the override on Cat ET. Activate the override for the air shutoff.

4. Monitor the voltage between the wires at the solenoid.

5. Deactivate the override for the air shutoff.

Expected Result:

The voltage is 24 ± 3 VDC.

Results:

• OK - The voltage is 24 ± 3 VDC.

  Repair: Check the connections at the solenoid for damage. If the connections are okay, install a new air shutoff solenoid.

  STOP

• Not OK - The voltage is not 24 ± 3 VDC.

  Repair: Repair the wire G971-BR between the air shutoff relay and the air shutoff solenoid(s).

  STOP

Test Step 8. Check the Output Voltage at the ECM

1. Turn the breaker for the ECM to the OFF position.

2. Turn the switch that provides power to the keyswitch input for the ECM to the OFF position.

3. Disconnect the ECM connectors J2/P2.

4. Remove wire G971-BR in socket P2-13 from ECM connector P2. Install a wire jumper into the socket for P2-13.

5. Reconnect ECM connector J2/P2.

6. Connect a voltmeter between the wire jumper in socket P2-13 and engine ground.

7. Turn the breaker for the ECM to the ON position.

8. Turn the switch that provides power to the keyswitch input for the ECM to the ON position.

9. Access the override on Cat ET. Activate the override for the air shutoff.

10. Monitor the voltage between the wire jumper in socket P2-13 and engine ground.

11. Deactivate the override for the air shutoff.

12. Turn the breaker for the ECM to the OFF position.

13. Turn the switch that provides power to the keyswitch input for the ECM to the OFF position.

14. Remove the wire jumper. Reinstall all wires. Reconnect ECM connector J2/P2.

Expected Result:

The voltage is 24 ± 3 VDC.

Results:

• OK - The voltage is 24 ± 3 VDC. The problem appears to be in the wiring between the ECM and the air shutoff solenoid.

  Repair: Repair the wiring or replace the wiring between the ECM and the air shutoff solenoid.

  STOP

• Not OK - The voltage is not 24 ± 3 VDC.

  Repair: The ECM did not output the correct voltage. Replace the ECM. Refer to Troubleshooting, "Replacing the ECM".

  STOP