3406E and 3456 Generator Set Engines Caterpillar

The Electronic Control Module (ECM) receives the start/run signal from the Generator Set Control (GSC). The parameters for the total number of crank cycles and the engine cooldown must be programmed to zero (0).

If the signals from the start/run/stop input to the ECM are in opposite states, the ECM determines that one of the signals is faulty. The ECM ignores the signals until power is cycled to the ECM.

336-02 (Incorrect ECS Switch Inputs) will be active until the ECM is powered down. The status for the ignition switch will display "ABNORMAL DATA" until power to the ECM is cycled.

If the engine is running and the signals from the start/run/stop input to the ECM change to opposite states, the engine will continue to run. The ECM generates a diagnostic code that will remain active until power to the ECM is cycled. When the engine is shutdown, the ECS must be placed in the OFF/RESET position. This will disconnect power to the ECM.

Note: For troubleshooting applications that are equipped with a EMCP II, refer to Service manual, RENR2483, "Electronic Modualr Control Panel II (EMCP II)". For troubleshooting applications that are equipped with a EMCP II +, refer to Service Manual, RENR2484, "Electronic Modular Control Panel II + (EMCP II +)".

Illustration 1	g01067483
Schematic for the ECS with EMCP II

Test Step 1. CHECK FOR CONNECTOR DAMAGE.

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

2. Turn the battery disconnect switch to the OFF position.

3. Thoroughly inspect the ECM connectors J1/P1 and J2/P2. Inspect all of the other connectors. Refer to the diagnostic functional test Troubleshooting, "Inspecting Electrical Connectors" for details.

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

5. Check the ECM connector (allen head screw) for the proper torque of 6.0 N·m (55 lb in).

6. Check the customer connector (allen head screw) for the proper torque of 2.25 ± 0.25 N·m (20 ± 2 lb in).

7. Check the harness and the 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 okay. Proceed to Test Step 2.

• Not OK - The connectors and/or wiring are not okay.

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

  STOP

Test Step 2. CHECK THE VOLTAGE TO THE ECM.

1. Remove ECM connector J1/P1.

2. Turn the battery disconnect switch to the ON position.

3. Turn the ECS to the STOP position.

4. Measure the voltage between P1:6 +Batt and P1:5 -Batt.

5. Measure the voltage between P1:4 unswitched +Batt and P1:11 +Batt.

6. Measure the voltage between P1:23 switch 1 and P1:11 +Batt.

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

8. Turn the battery disconnect switch to the OFF position.

9. Reconnect ECM connector J1/P1.

Expected Result:

The voltage is 24 ± 3 VDC.

Results:

• OK - The voltage is 24 ± 3 VDC. The ECM is receiving the correct voltage. Proceed to Test Step 4.

• Not OK - The voltage is not 24 ± 3 VDC. The voltage is incorrect. The battery or the alternator may be causing the problem. Proceed to Test Step 3.

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

Test Step 3. CHECK THE BATTERY VOLTAGE.

1. Measure the open circuit voltage at the battery terminals. Refer to Testing and Adjusting, "Test Tools for the Electrical System" for the proper procedures to check the batteries.

2. Load test the batteries. Use the 4C-4911 Battery Load Tester. Refer to the Operating Manual, SEHS9249. Refer to Special Instruction, SEHS7633.

Expected Result:

The open circuit voltage at the batteries is at least 24 ± 1 VDC, and the batteries should pass the load test.

Results:

• OK - The open circuit voltage at the batteries is 24 ± 1 VDC, and the batteries pass the load test.

  Repair: There is a problem in the harness. Repair the connectors and/or wiring or replace the connectors and/or wiring between the battery and the ECM.

  STOP

• Not OK - The battery voltage is incorrect and/or the battery fails the load test.

  Repair: The batteries or the alternator are causing the problem. Recharge the batteries or replace the batteries. Verify that the original condition is resolved. Refer to Testing and Adjusting, "Electrical System".

  STOP

Test Step 4. CHECK THE VOLTAGE AT THE SENSOR POWER SUPPLIES.

1. Disconnect ECM connector J1/P1.

2. Remove the following wires from ECM connector P1. Install a wire jumper for each of the following wires that are removed.

   • P1:36 (Analog power)

   • P1:30 (Analog return)

   • P1:35 (Digital power)

   • P1:29 (Digital return)

3. Reconnect ECM connector J1/P1.

4. Turn the battery disconnect switch to the ON position.

5. Turn the ECS to the STOP position.

6. Measure the voltage from the analog sensor supply P1:36 to the analog sensor return P1:30.

7. Measure the voltage from digital sensor supply P1:35 to the digital sensor return P1:29.

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

9. Turn the battery disconnect switch to the OFF position.

10. Remove the wire jumpers. Replace all wires.

Expected Result:

The voltage is 5.0 ± 0.2 VDC between P1:36 and P1:30. The voltage is 8.0 ± 0.4 VDC between P1-35 and P1-29.

Results:

• OK - The sensor power supplies are functioning properly. The ECM is powered up. The problem is not in the electrical system.

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

  STOP

• Not OK - If the ECM is getting the correct voltage at the +Battery terminal, but the ECM does not supply the correct voltages to the sensors, replace the ECM.

  Repair: Refer to the diagnostic procedure Troubleshooting, "Replacing the ECM".

  STOP

Test Step 5. CHECK THE WIRING FOR AN OPEN CONDITION

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

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

3. Disconnect J1/P1 ECM connector.

4. Disconnect RM13 and RM14 on the GSC.

5. Measure the resistance between P1:13 (Start/run/stop 2) and P1:14 (Start/run/stop 2).

6. Short the wire terminals that were connected to RM13 and RM14 together. Ensure that the wires are isolated from the other components.

7. Measure the resistance between P1:29 (Digital sensor return) and P1:13 (Start/run/stop 2).

Expected Result:

The resistance is less than 10 Ohms.

Results:

• OK - Proceed to Test Step 6.

• Not OK - There is an open circuit condition between the ECM and the GSC.

  Repair: Repair the wiring or replace the wiring between the ECM and the GSC. Verify that the repairs have eliminated the problem.

  STOP

Test Step 6. CHECK THE WIRING FOR SHORTS

1. Remove the short between the wire terminals that were attached to RM13 and RM14. Ensure that the individual wires are kept isolated from the other components.

2. Measure the resistance between P1:29 (Digital sensor return) and P1:14 (Start/run/stop 1).

3. Measure the resistance between P1:29 (Digital sensor return) and P1:13 (Start/run/stop 2).

Expected Result:

The resistance is greater than 20,000 Ohms.

Results:

• OK - The wiring between the ECM and the GSC is OK.

  Repair: For troubleshooting applications that are equipped with a EMCP II, refer to Service manual, RENR2483, "Electronic Modualr Control Panel II (EMCP II)".

  For troubleshooting applications that are equipped with a EMCP II +, refer to Service Manual, RENR2484, "Electronic Modular Control Panel II + (EMCP II +)".

  STOP

• Not OK - There is a short circuit in the wiring between the ECM and the GSC.

  Repair: Repair the wiring or replace the wiring. Verify that the repair has eliminated the problem.

  STOP