3512C and 3516C Engines Caterpillar

Use this procedure in order to troubleshoot the electrical system if a problem is suspected with the remote emergency stop switch. Use this procedure if the diagnostic code in Table 1 is active or easily repeated.

The customer's remote emergency stop switch sends two signals to the Electronic Control Module (ECM). The signals are used to determine if the remote emergency stop switch is active. The customer's remote emergency stop switch is active when the switch is in the open state and the two signals are high. The customer's remote emergency stop switch is inactive when the switch is in the closed state and the two signals are held low.

If the ECM is powering up and one of the signals from the customer's remote emergency stop switch is in a different state from the other signal, the ECM determines that one of the signals is faulty. If one of the signals from the customer's remote emergency stop switch is in a different state from the other signal, the ECM will generate a diagnostic code that remains active until power to the ECM is cycled. The ECM will not allow the crank cycle to begin if the signals are opposite of each other. The ECM will allow the engine to be started manually in this state.

The ECM monitors the inputs from the customer's remote emergency stop signals at all times. If the engine is running and one of the signals from the customer's remote emergency stop switch changes states, the engine will continue to run. The ECM initiates an emergency stop shutdown only when both signals are high during engine operation.

Relay "R3A" and relay "R3" are energized through terminal 3 of the diode assembly. Terminal 3 of the diode assembly will energize relay "R3A" and relay "R3" for 1 second. The contacts of relay "R3" keep relay "R3A" and relay "R3" energized until the Engine Control Switch (ECS) is cycled to the OFF/RESET position. The contacts of relay "R3A" energizes the coil of relay "R2A". When relay "R2A" is energized, power is removed from the ECM. The ECM will power down. The injection signals to the injector solenoids will stop.

The contacts of relay "R3A" also supply power to terminal 3 of the connector for a timer. When power is applied to terminal 3 of the connector for the timer, the timer will activate. The timer outputs 24 VDC from terminal 6 of the connector for the timer for 2.5 seconds. The 24 VDC from the timer is applied to the coil of the "ASOS" switch and to terminal 2 of the diode assembly. The "ASOS" switch energizes the two air shutoff solenoids. The solenoids trip the air shutoff valves. The 2.5 second time limit for activation of the "ASOS" switch prevents damage to the air shutoff solenoids. A normally open switch at the air shutoff valves will close when the air shutoff solenoid activates the air shutoff valve. The switch inputs a signal to the ECM. The signal notifies the ECM that the air shutoff valves are closed. The ECM will not send injection signals to the injector solenoids until the switch inputs from the air shutoff valves indicate that the valves are open. The air shutoff valve must be manually opened in order to start the engine.

The ECM will not allow the starting sequence to begin when the customer's remote emergency stop switch is activated. The engine will not be able to restart until the following conditions are met:

• The engine rpm must equal zero.

• The inputs from the customer's remote emergency stop must go low.

• The ECM has been reset.

The electrical power to the input for the keyswitch must be turned OFF for three seconds in order to reset the engine ECM after an emergency stop condition.

Note: If one of the inputs from the customer's remote emergency stop switch is in a different state from the other signal, the Caterpillar Electronic Technician (ET) will display the warning "INVALID DATA".

Illustration 1	g01329445
Typical schematic

Illustration 2	g01218361
P1 ECM connector (P1-5) Digital return (P1-23) Emergency stop signal 1 (P1-28) Emergency stop signal 2

Illustration 3	g01323796
Terminal locations for the TB-C1/C-C18 customer connector (Terminal U) "E-Stop 1" (Terminal T) "E-Stop 2"

Illustration 4	g01322302
Terminal locations for the following connectors P-C1/A-C90 Connector for the power distribution panel, A-C2/J-C2 RH rigid harness connector and C-C2/J-C1 LH rigid harness connectors (Terminal G) Drive for the air shutoff switch F708-BK(Black) (Terminal H) Return for the air shutoff solenoid H708-BK(Black) (Terminal I) Drive for the air shutoff solenoid G708-BK(Black)

Illustration 5	g01320528
Connector locations (1) A-C1/E-C2 RH rigid harness connectors (2) A-C2/J-C2 RH rigid harness connectors (3) P-C1/A-C90 Connectors for the power distribution panel (4) P-C2/A-C91 Connectors for the power distribution panel (5) G-C6/F-C2/F-C1/A-C92 Connectors for a RH Control panel (6) C-C22 Primary ECM connector P2 (7) C-C15 Primary ECM connector P1 (8) C-C28 Secondary ECM connector P2 (9) C-C29 Secondary ECM connector P1 (10) G-C6/F-C2/F-C1/C-C17 Connectors for a LH Control panel (11) TB-C1/C-C18 Customer connectors (12) C-C2/J-C1 LH rigid harness connectors (13) C-C1/E-C1 LH rigid harness connectors

Illustration 6	g01234146
Location of ECM connectors

Test Step 1. Inspect the Electrical Connectors and the Wiring for the Customer's Emergency Stop

Note: The 337-2 diagnostic code is generated because of a problem with the emergency stop inputs to the ECM from the customer connector. The two signals should be at a low potential or the two signals should be at a high potential. When the two signals are at a different potential from each other the diagnostic code is generated.

1. Turn the circuit breaker for the battery to the OFF position.

2. Turn the ECS to the OFF/RESET position.

3. Disconnect the following connectors.

   • C-C18 customer connector

   • P1 ECM connector

   • P2 ECM connector

4. Check for an open circuit in the wiring.

   1. Install a wire jumper between terminal U and terminal T at the customer connector.

   2. Measure the resistance between P1-23 and P1-28 on the P1 ECM connector. Wiggle the harness while performing the resistance checks.

   3. Remove the wire jumper.

5. Check for a short circuit in the wiring.

   1. Measure the resistance between wire F715-BK(Black) and every wire on the following connectors.

      • C-C18 customer connector

      • P1 ECM connector

      • P2 ECM connector

   2. Measure the resistance between wire F719-BK(Black) and every wire on the following connectors.

      • C-C18 customer connector

      • P1 ECM connector

      • P2 ECM connector

Expected Result:

The resistance checks indicate a short circuit when the wire jumper is installed. The resistance checks indicate an open circuit when the wire jumper is removed.

Results:

• OK - The harness and wiring appear to be OK. Verify that the two input signals on terminal U and terminal T from the customer connector TB-C1 are at the same potential before proceeding. Proceed to Test Step 2.

• Not OK - There is a problem in the connectors and/or wiring.

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

  STOP

Test Step 2. Test the Air Shutoff System

1. Turn the circuit breaker for the battery to the ON position.

2. Turn the ECS to the STOP position. The engine should be off.

3. Activate the customer's emergency stop switch.

4. Monitor the air shutoff solenoids.

5. Deactivate the customer's emergency stop switch.

Expected Result:

The air shutoff solenoids activated.

Results:

• OK - The air shutoff solenoids activated correctly.

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

  STOP

• Not OK - The air shutoff solenoids failed to activate. Proceed to Test Step 3.

Test Step 3. Check for the Voltage from the "ASOS" Switch at the Connector P-C1/A-C90 for the Power Distribution Panel

1. Turn the ECS to the STOP position. The engine should be off.

2. Remove wire G708-BK(Black) from terminal "I" of connector A-C90. Install a wire jumper into the connector for wire G708-BK(Black).

3. Activate the customer's emergency stop switch.

4. Monitor the voltage on the wire jumper in terminal I at connector A-C90 of the rigid harness. Refer to Illustration 1 for terminal locations.

5. Deactivate the customer's emergency stop switch.

6. Return all wiring to the original configuration.

Expected Result:

The voltage measures 24 ± 3 VDC for approximately 2.5 seconds.

Results:

• OK - The voltage measures 24 ± 3 VDC for approximately 2.5 seconds. The circuit is operating correctly to this point. Proceed to Test Step 7.

• Not OK - The voltage did not measure 24 ± 3 VDC for approximately 2.5 seconds. Proceed to Test Step 4.

Test Step 4. Test for Voltage to the Coil of the "ASOS" Switch at the Connector A-C90 for the Power Distribution Panel

1. Remove wire F708-BK(Black) from terminal "G" of connector A-C90. Install a wire jumper into the connector for wire F708-BK(Black).

2. Turn the ECS to the STOP position.

3. Activate the customer's emergency stop switch.

4. Monitor the voltage on the wire jumper in terminal G at connector A-C90 of the rigid harness. Refer to Illustration 1 for terminal locations.

5. Deactivate the customer's emergency stop switch.

6. Return all wiring to the original configuration.

Expected Result:

The voltage measures 24 ± 3 VDC for approximately 1 second.

Results:

• OK - The voltage measures 24 ± 3 VDC for approximately 1 second. The circuit is operating correctly to this point. Proceed to Test Step 5.

• Not OK - No voltage was measured. Proceed to Test Step 14.

Test Step 5. Test for Voltage to the Coil of the "ASOS" Switch

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

2. The input to the coil of the "ASOS" switch is wire T708-BK(Black) from the diode assembly. Disconnect wire T708-BK(Black) from the "ASOS" switch. Connect a voltmeter between wire T708-BK(Black) and the engine ground.

   Note: The "ASOS" switch is turned on for one second by the ECM. The timer keeps the "ASOS" switch energized for approximately 2.5 seconds.

3. Turn the ECS to the STOP position.

4. Activate the customer's emergency stop switch.

5. Monitor the voltage on the voltmeter.

6. Deactivate the customer's emergency stop switch.

7. Return all wiring to the original configuration.

Expected Result:

The voltage measures 24 ± 3 VDC for approximately 2.5 seconds.

Results:

• OK - The voltage measures 24 ± 3 VDC for approximately 2.5 seconds. The circuit is operating correctly to this point. Proceed to Test Step 6.

• Not OK - No voltage was measured. Proceed to Test Step 10.

• Not OK - The voltage did not measure 24 ± 3 VDC for 2.5 seconds. Proceed to Test Step 8.

Test Step 6. Check for Voltage from the "ASOS" Switch to the Air Shutoff Solenoids

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

2. Disconnect wire G708-BK(Black) from the "ASOS" switch.

3. Connect a voltmeter to the empty terminal on the "ASOS" switch. Connect the other lead of the voltmeter to engine ground.

4. Turn the ECS to the STOP position. The engine should be off.

5. Activate the customer's emergency stop switch.

6. Monitor the voltage on the voltmeter.

7. Deactivate the customer's emergency stop switch.

8. Reconnect wire G708-BK(Black) to the "ASOS" switch.

Expected Result:

The voltage measures 24 ± 3 VDC for approximately 2.5 seconds.

Results:

• OK - The voltage measures 24 ± 3 VDC for approximately 2.5 seconds. The circuit is operating correctly to this point.

  Repair: Repair the wire G708-BK(Black) between the "ASOS" switch and terminal I at connector P-C1 of the power distribution panel.

  STOP

• Not OK - The voltage did not measure 24 ± 3 VDC for approximately 2.5 seconds.

  Repair: Verify that 24 ± 3 VDC is present on wire K708-BK(Black) at the normally open contacts of the "ASOS" switch. If voltage is not present on wire K708-BK(Black), check the wiring and the circuit breaker for the air shutoff for problems.

  Check wire 220-BK(Black) on the coil of the "ASOS" switch for continuity to the −Battery. If necessary, repair the wire or replace the wire.

  If wire 220-BK(Black) is OK and voltage is present on wire K708-BK(Black), replace the "ASOS" switch.

  STOP

Test Step 7. Check the Voltage at the Connector for the Air Shutoff Solenoids

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

2. Disconnect the connector for the air shutoff solenoids. Disconnect the connector for the right and left sides of the engine.

3. Connect a voltmeter between wire G708-BK(Black) on the connector for the air shutoff solenoid and the engine ground.

4. Turn the ECS to the STOP position. The engine should be off.

5. Activate the customer's emergency stop switch.

6. Monitor the voltage on the voltmeter.

7. Deactivate the customer's emergency stop switch.

8. Reconnect the connectors for the air shutoff solenoids.

Expected Result:

The voltage measures 24 ± 3 VDC for approximately 2.5 seconds.

Results:

• OK - The voltage measures 24 ± 3 VDC for approximately 2.5 seconds. The circuit is operating correctly to this point.

  Repair: Check the wire H708-BK(Black) from terminal A of the connector for the air shutoff solenoid for continuity to the −Battery terminal. If the wire H708-BK(Black) to the −Battery terminal is OK, replace the air shutoff solenoid.

  STOP

• Not OK - The voltage did not measure 24 ± 3 VDC for approximately 2.5 seconds. System voltage was not available at the solenoid connector.

  Repair: Repair the wire G708-BK(Black) between the connector for the air shutoff solenoids and terminal I at connector A-C90 of the rigid harness. Refer to Illustration 1 for a schematic of the circuit.

  STOP

Test Step 8. Check the Voltage at the Contact of Relay "R3A"

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

2. Disconnect wire T120-BK(Black) from terminal 87 of relay "R3A".

3. Connect a voltmeter between terminal 87 of relay "R3A" and the engine ground.

4. Turn the ECS to the STOP position.

5. Activate the customer's emergency stop switch.

6. Monitor the voltage on the voltmeter.

7. Deactivate the customer's emergency stop switch.

8. Reconnect wire T120-BK(Black).

Expected Result:

The voltage measures 24 ± 3 VDC.

Results:

• OK - The voltage measures 24 ± 3 VDC. Proceed to Test Step 9.

• Not OK - The voltage did not measure 24 ± 3 VDC. Proceed to Test Step 11.

Test Step 9. Check the Voltage at Terminal 6 of the Connector for the Timer

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

2. Connect a voltmeter between terminal 6 of the connector for the timer and engine ground.

3. Turn the ECS to the STOP position.

4. Activate the customer's emergency stop switch.

5. Monitor the voltage on the voltmeter.

6. Deactivate the customer's emergency stop switch.

Expected Result:

The voltage measures 24 ± 3 VDC for approximately 2.5 seconds.

Results:

• OK - The voltage measures 24 ± 3 VDC for approximately 2.5 seconds. Proceed to Test Step 12.

• Not OK - The voltage did not measure 24 ± 3 VDC for approximately 2.5 seconds.

  Repair: Check for 24 ± 3 VDC on terminal 3 of the connector for the timer. If voltage is not present on terminal 3, repair the wire T120-BK(Black) between terminal 87 of relay "R3A" and terminal 3 of the connector for the timer.

  If voltage is present on terminal 3 of the connector for the timer, verify that wire 220-BK(Black) on terminal 2 of the connector for the timer has continuity to the −Battery. If wire 220-BK(Black) does not have continuity to the −Battery, repair the wire.

  Verify that 24 ± 3 VDC is present on terminal 1 of the connector for the timer. If 24 ± 3 VDC is not present on terminal 1 of the connector for the timer, verify that the engine control switch is not in the "OFF/RESET" position. Verify that the "MPD" breaker is not tripped. Check the normally closed contact of relay "R1" for proper operation. Check the wire 120 between terminal 1 of the connector for the timer and relay "R1" for damage. Check the wire A120 between relay "R1" and the "MPD" breaker for damage. If necessary, repair the wires.

  If the voltage is present on terminal 1 and terminal 3 of the timer and wire 220-BK(Black) is OK, replace the timer.

  STOP

Test Step 10. Check the Voltage at Terminal 4 of the Connector for the Diodes

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

2. Disconnect wire T708-BK(Black) from terminal 4 of the connector for the diodes.

3. Connect a voltmeter between terminal 4 of the connector for the diodes and the engine ground.

4. Turn the ECS to the STOP position.

5. Activate the customer's emergency stop switch.

6. Monitor the voltage on the voltmeter.

7. Deactivate the customer's emergency stop switch.

Expected Result:

The voltage measures 24 ± 3 VDC for approximately 2.5 seconds.

Results:

• OK - The voltage measures 24 ± 3 VDC for approximately 2.5 seconds.

  Repair: Repair the wire T708 between the connector for the diodes and the "ASOS" switch.

  STOP

• Not OK - The voltage did not measure 24 ± 3 VDC for approximately 2.5 seconds.

  Repair:

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

  2. Disconnect wire F708-BK(Black) from terminal 1 of the connector for the diodes.

  3. Connect a voltmeter between wire F708-BK(Black) and the engine ground.

  4. Turn the ECS to the STOP position.

  5. Activate the customer's emergency stop switch.

  6. Monitor the voltage on the voltmeter.

  7. Deactivate the customer's emergency stop switch.
  If the voltage measures 24 ± 3 VDC for approximately 1 second, replace the diodes.

  If the voltage does not measure 24 ± 3 VDC for approximately 1 second, repair the wire F708-BK(Black) between the connector for the diodes and wire F708-BK(Black) on pin G at connector A-C90 of the right rail.

  STOP

Test Step 11. Check the Voltage at the Coil of Relay "R3A"

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

2. Disconnect wire 918-BK(Black) from terminal 86 of relay "R3A".

3. Connect a voltmeter between wire 918-BK(Black) and the engine ground.

4. Turn the ECS to the STOP position.

5. Activate the customer's emergency stop switch.

6. Monitor the voltage on the voltmeter.

7. Deactivate the customer's emergency stop switch.

8. Return all wiring to the original configuration.

Expected Result:

The voltage measures 24 ± 3 VDC.

Results:

• OK - The voltage measures 24 ± 3 VDC.

  Repair: Check wire 220-BK(Black) on the coil of the "R3A" relay for continuity to the −Battery. If necessary, repair the wire or replace the wire.

  Check for 24 ± 3 VDC on wire 120-BK(Black) on terminal 30 of relay "R3A". If 24 ± 3 VDC is not present on wire 120-BK(Black), verify that the engine control switch is not in the "OFF/RESET" position. Verify that the "MPD" breaker is not tripped. Check the normally closed contact of relay "R1" for proper operation. Check the wire 120-BK(Black) between terminal 30 of the relay "R3A" and relay "R1" for damage. Check the wire 120-BK(Black) between relay "R1" and the "MPD" breaker for damage. If necessary, repair the wires.

  If wire 220-BK(Black) is OK and voltage is present on wire 120-BK(Black) on terminal 30, replace relay "R3A".

  STOP

• Not OK - The voltage did not measure 24 ± 3 VDC. Proceed to Test Step 13.

Test Step 12. Check the Voltage to Terminal 2 of the Connector for the Diodes from the Timer

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

2. Connect a voltmeter between the terminal 2 of the connector for the diodes and the engine ground.

3. Turn the ECS to the STOP position. The engine should be off.

4. Activate the customer's emergency stop switch.

5. Monitor the voltage on the voltmeter.

6. Deactivate the customer's emergency stop switch.

Expected Result:

The voltage measures 24 ± 3 VDC.

Results:

• OK - The voltage measures 24 ± 3 VDC. Proceed to Test Step 13.

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

  Repair: Repair the wire T708-BK(Black) between the diodes and the timer.

  STOP

Test Step 13. Check the Voltage from Terminal 3 of the Connector for the Diode Assembly

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

2. Connect a voltmeter between terminal 3 of the connector for the diode assembly and the engine ground.

3. Turn the ECS to the STOP position. The engine should be off.

4. Activate the customer's emergency stop switch.

5. Monitor the voltage on the voltmeter.

6. Deactivate the customer's emergency stop switch.

Expected Result:

The voltage measures 24 ± 3 VDC.

Results:

• OK - The voltage measures 24 ± 3 VDC.

  Repair: Repair the wire 918-BK(Black) between the diodes and relay "R3A".

  STOP

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

  Repair: Replace the diodes.

  STOP

Test Step 14. Check the Output Driver for the Air Shutoff System at the ECM

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

2. Disconnect the ECM connector P2.

3. Remove wire F708-BK(Black) from ECM connector P2-13. Install a wire jumper into P2-13.

4. Reconnect ECM connector P2.

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

6. Turn the ECS to the STOP position.

7. Activate the customer's emergency stop switch.

8. Monitor the voltage on the voltmeter.

9. Deactivate the customer's emergency stop switch.

10. Return all wiring to the original configuration.

Expected Result:

The voltage measures 24 ± 3 VDC for one second.

Results:

• OK - The voltage measures 24 ± 3 VDC for one second.

  Repair: Repair the wire F708-BK(Black) between the ECM connector and terminal G at connector A-C90 of the rigid harness. Refer to Illustration 1 for a schematic of the circuit. Check for voltage at the following connectors C-C2/J-C1 LH rigid harness connectors and A-C2/J-C2 RH rigid harness connectors.

  STOP

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

  Repair: Monitor the status screen for the emergency stop in order to verify that the ECM is receiving the emergency stop signal. If the ECM is receiving the emergency stop signal from the customer connector, replace the ECM. If the ECM is not receiving the emergency stop signal from the customer connector, repair the wiring between the ECM and the customer connector.

  STOP