3500B Marine Engines Caterpillar

The Electronic Control Module (ECM) stores the firing order of the injectors. The firing order is for engines with standard rotation and reverse rotation. A single part number can be used for either engine. The ECM must be programmed for the correct direction of rotation.

Two ECM signals determine the direction of engine rotation. One input for the primary ECM must be connected to the digital return. One input for the secondary ECM must be connected to the digital return. The other input of both electronic control modules must remain unconnected.

Standard rotation CCW

• P1-34 of the primary ECM must be connected to the digital return P1-29.

• P1-40 of the primary ECM must be unconnected.

• P1-34 of the secondary ECM must be connected to the digital return P1-29.

• P1-40 of the secondary ECM must be unconnected.

Reverse rotation CW.

• P1-40 of the primary ECM must be connected to the digital return P1-29.

• P1-34 of the primary ECM must be unconnected.

• P1-40 of the secondary ECM must be connected to the digital return P1-29.

• P1-34 of the secondary ECM must be unconnected.

Note: Standard rotation is counterclockwise when you are facing the rear of the engine. Reverse rotation is clockwise when you are facing the rear of the engine.

Illustration 1	g00601535

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, and 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 Rotation on the Caterpillar Electronic Technician (ET).

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

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

3. Turn the ECS to the STOP position.

4. Observe the engine rotation on the Cat ET. Observe the engine rotation for both the primary ECM and the secondary ECM.

Expected Result:

The Cat ET should display the standard or reverse rotation.

Results:

• OK - The Cat ET displays the standard or reverse rotation.

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

  STOP

• Not OK - If the Cat ET displays "UNDEFINED", the ECM is not receiving the correct input. Proceed to Test Step 3.

Test Step 3. Check the Harness Resistance of the Rotation Enable Circuit.

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

2. Disconnect the ECM connector P1 from the primary ECM and from the secondary ECM.

3. Measure the resistance from each signal line to P1-29 for both the Primary ECM and the Secondary ECM.

4. Measure the resistance from P1-34 to P1-29.

5. Measure the resistance from P1-40 to P1-29.

Expected Result:

Standard rotation CCW

The resistance from P1-34 to P1-29 should be less than 5 Ohms.

The resistance from P1-40 to P1-29 should be greater than 20,000 Ohms.

Reverse rotation CW.

The resistance from P1-34 to P1-29 should be greater than 20,000 Ohms.

The resistance from P1-40 to P1-29 should be less than 5 Ohms.

Results:

• OK - The resistance measurements are correct for standard rotation and for reverse rotation. Proceed to Test Step 4.

• Not OK - The resistance measurements are incorrect for standard rotation and/or reverse rotation.

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

  STOP

Test Step 4. Check the Harness for a Short to Ground.

1. Measure the resistance from each signal line to engine ground for both the primary ECM and the secondary ECM.

2. Measure the resistance from P1-34 to engine ground.

3. Measure the resistance from P1-40 to engine ground.

4. Measure the resistance from P1-29 to engine ground.

Expected Result:

The resistance should be more than 20,000 Ohms.

Results:

• OK - The resistance is more than 20,000 Ohms.

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

  STOP

• Not OK - The resistance is less than 20,000 Ohms.

  Repair: There is a short in the harness. Repair the connectors or wiring and/or replace the connectors or wiring.

  STOP