3500B Marine Engines Caterpillar

The Primary Electronic Control Module (ECM) receives four input signals from the Engine Control Switch (ECS). The input signals allow the ECM to determine the mode of operation. The ECS can operate in four modes: OFF/RESET, MAN/START, COOLDOWN/STOP and AUTO.

When the ECS is set to the OFF/RESET position, the START/RUN/STOP INPUT and the AUTO input are open. The ECM is not powered. Engine operation will stop when the ECS is switched to this position.

When the ECS is set to the AUTO position, the START/RUN/STOP INPUT is open and the AUTO input is low. The ECM is powered. If the remote START/STOP Switch is closed, the engine start sequence will begin.

When the ECS is set to the MAN/START position, The START/RUN/STOP INPUT is low and the ECS in AUTO input is open. The ECM will begin the engine start sequence.

When the ECS is set to the COOLDOWN/STOP position, the START/RUN/STOP INPUT and the ECS in AUTO input are open. After the engine cooldown, the ECM will shut down the engine.

If the signals from the START/RUN/STOP INPUT are opposite, the ECM determines that one of the signals is faulty. The ECM ignores the signals until power is cycled to the ECM.

If this occurs, the engine must be cranked manually. Use the Manual Crank Switch which is located inside the Instrument Panel. When the engine is shut down, the ECS must be placed in the OFF/RESET position. This will disconnect power to the ECM. A CID-FMI will be active until the ECM is powered down. The status for the ECS will display "ABNORMAL DATA" until power to the ECM is cycled.

If you close the remote START/RUN/STOP switch and the ECS is in the AUTO position, the engine will start. The status for the ECS will display "ON" or "OFF". This parameter is available on the Caterpillar Electronic Technician (ET) only when the ECS is in the AUTO position.

Note: Turn the breaker for the "MAG Relays" to the OFF position for this test. After completing this test, turn the breaker for the "MAG Relays" to the ON position.

Illustration 1	g00720787
Typical example

Test Step 1. Check for Connector Damage.

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

2. Turn the ECS to the OFF/RESET 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 2.25 ± 0.25 N·m (20 ± 2 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. The harness and wiring should be free of corrosion, of abrasion or of pinch points.

Results:

• OK - The connectors and wiring are okay. Proceed to Test Step 2.

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

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

  STOP

Test Step 2. Check the Status of the ECS in the STOP Position.

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

2. Connect the Cat ET to the service tool connector.

3. Turn the ECS to the STOP position.

4. Observe the status for the ECS on the Cat ET.

Expected Result:

The status for the ECS should read "STOP".

Results:

• OK - The ECS is functioning correctly. Proceed to Test Step 3.

• Not OK - The status for the ECS does not display "STOP". Proceed to Test Step 4.

Test Step 3. Check the Status of the ECS in the START Position.

1. Turn the ECS to the START position.

2. Observe the status for the ECS on the Cat ET.

Expected Result:

The status for the ECS should read "RUN".

Results:

• OK - The ECS is functioning correctly. Proceed to Test Step 5.

• Not OK - The status of the ECS does not display "RUN". Proceed to Test Step 4.

Test Step 4. Install a Jumper Wire.

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

2. Disconnect the primary ECM connector P1. Remove wires P1-14, P1-8 and P1-29.

3. Fabricate a jumper wire.

4. Install the jumper wire at P1. Connect the jumper wire between P1-14 and P1-8 to P1-29. Reconnect P1.

5. Turn the ECS to the STOP position.

6. Observe the status for the ECS on the Cat ET.

7. Turn the ECS to the OFF/RESET position and remove the jumper wire.

Expected Result:

The status for the ECS should display "RUN" while the jumper wire is installed. The status for the ECS should display"STOP" when the jumper wire is removed.

Results:

• OK - The status for the ECS displays the proper states. The problem is not with the ECM. Proceed to Test Step 6.

• Not OK - The status for the ECS does not show the correct states.

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

  STOP

Test Step 5. Check the Status of the ECS in the AUTO Position.

1. Turn the ECS to AUTO. Place the Remote START/STOP Switch in the START position.

2. Observe the status for the ECS on the Cat ET. Observe the parameters for the remote start on the Cat ET.

Expected Result:

The status for the ECS should read "AUTO". The status for the remote start should read "ON".

Results:

• OK - The ECS and the remote START/STOP switch are working correctly.

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

  STOP

• Remote Start Not OK - The status for the remote start does not display "ON". There is a problem with the wiring between the remote START/STOP switch and the ECS. Proceed to Test Step 7.

• ECS Not OK - The status for the ECS does not display "AUTO". Proceed to Test Step 8.

Test Step 6. Check Switches and the Wiring.

1. Turn the ECS to the OFF position.

2. Disconnect ECM connector J1/P1.

3. Measure the resistance between the digital return, P1-29 and the Start/Run/Stop input 1 at the ECM connector P1-8.

4. Measure the resistance between the digital return, P1-29 and the Start/Run/Stop input 2 at the ECM connector P1-14.

5. Turn the ECS to the STOP position and repeat the above two measurements.

Expected Result:

The resistance should be greater than 20,000 Ohms.

Results:

• OK - The resistance is greater than 20,000 Ohms. Proceed to Test Step 9.

• Not OK - The resistance is less than 20,000 Ohms. There is a short circuit in the ECS and/or the wiring between the ECS and the ECM.

  Repair: Repair the connectors or wiring and/or replace the connectors or wiring. If the wiring is okay, replace the ECS.

  STOP

Test Step 7. Check the Switches and the Wiring.

the ECM connector

1. Turn the ECS to the AUTO position with the Remote START/STOP Switch in the STOP position.

2. Measure the resistance between the digital sensor return P1-29 and the Start/Run/Stop Input 1 at the ECM connector P1-8.

3. Measure the resistance between the digital sensor return P1-29 and the Start/Run/Stop Input 2 at the ECM connector P1-14.

Expected Result:

The resistance should be greater than 20,000 Ohms.

Results:

• OK - The resistance is greater than 20,000 Ohms. The ECS appears to be functioning properly. Proceed to Test Step 10.

• Not OK - The resistance is less than 20,000 Ohms. There is a short circuit in the ECS and/or the wiring between the ECS and the ECM.

  Repair: Repair the connectors or wiring and/or replace the connectors or wiring. If the wiring is okay, replace the ECS.

  STOP

Test Step 8. Install a Jumper Wire.

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

2. Disconnect the primary ECM connector P1.

3. Remove wires P1-14, P1-8 and P1-29.

4. Fabricate a jumper wire.

5. Install the jumper wire at P1. Connect P1-14 and P1-8 to P1-29. Reconnect P1.

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

7. Turn the ECS to the STOP position.

8. Observe the status for the ECS on the Cat ET.

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

10. Remove the jumper wire.

Expected Result:

The status for the ECS should read "AUTO" while the jumper wire is installed. The status for the ECS should read "STOP" when the jumper wire is removed.

Results:

• OK - The status for the ECS is displaying the proper states. The ECS is functioning correctly at this time.

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

  STOP

• Not OK - The status for the ECS does not display the correct states.

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

  STOP

Test Step 9. Check the Switches and the Wiring.

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

2. Turn the ECS to the START position.

3. Measure the resistance between the digital sensor return P1-29 and the Start/Run/Stop Input 1 at the ECM connector P1-8.

4. Measure the resistance between the digital sensor return P1-29 and the Start/Run/Stop Input 2 at the ECM connector P1-14.

Expected Result:

The resistance should read less than 10 Ohms.

Results:

• OK - The resistance is less than 5 Ohms. Proceed to Test Step 7.

• Not OK - The resistance is greater than 5 Ohms. There is an open circuit in the ECS and/or the wiring between the ECS and the ECM.

  Repair: Repair the connectors or wiring and/or replace the connectors or wiring. If the wiring is okay, replace the ECS.

  STOP

Test Step 10. Check the Switches and the Wiring.

1. Turn the ECS to the AUTO position . Ensure that the remote START/RUN/STOP switch is in the START/RUN position.

2. Measure the resistance between the digital sensor return P1-29 and the Start/Run/Stop input 1 at the ECM connector P1-8.

3. Measure the resistance between the digital sensor return P1-29 and the Start/Run/Stop input 2 at the ECM connector P1-14.

Expected Result:

The resistance should read less than 5 Ohms.

Results:

• OK - The resistance is less than 5 Ohms. The ECS appears to be functioning properly. Proceed to Test Step 8.

• Not OK - The resistance is greater than 5 Ohms. There is an open circuit in the ECS and/or the wiring between the ECS and the ECM.

  Repair: Repair the connectors or wiring and/or replace the connectors or wiring. If the wiring is okay, replace the ECS.

  STOP