3406E, C12, C15 and C18 Marine Engines Caterpillar

Note: If the vessel is equipped with a Multi-Station Control System (MSCS), refer to Service Manual, RENR7651, "Marine Multi-Station Control System" for the proper troubleshooting procedure.

This procedure tests whether proper voltage is being supplied to the Electronic Control Module (ECM).

Unswitched battery voltage is supplied through the customer connector to the ECM at P1:48, P1:52, and P1:53. The negative battery is supplied to the ECM at P1:61, P1:63, and P1:65. The ECM receives the input from the keyswitch at P1:70 when the keyswitch is in the ON position or the START position. When the ECM detects battery voltage at this input, the ECM will power up. When battery voltage is removed from this input, the ECM will power down.

The cause of an intermittent power supply to the ECM can occur on either the positive side or the negative side of the battery circuit. Both sides are routed from the ECM to the battery. The three connections for the unswitched +battery should be routed through a dedicated protective device (circuit breaker).

The engine ECM requires the keyswitch to be in the ON position in order to maintain communications with the electronic service tool.

For intermittent problems such as intermittent shutdowns that could be caused by engine wiring, temporarily bypassing the engine wiring may be an effective means of determining the root cause. If the symptoms disappear with the bypass wiring, the engine wiring is the cause of the problem. A means of bypassing engine wiring is explained in this test procedure.

Illustration 1	g00946101
Schematic (40-pin customer connector)

Illustration 2	g00946102
Schematic (70-pin customer connector)

Illustration 3	g00956626
P1 ECM connector

Test Step 1. Inspect Electrical Connectors and Wiring

1. Thoroughly inspect the J1/P1 ECM connector and the J61/P61 Customer connector. Also inspect the connections for the battery and the connections to the keyswitch. Refer to Troubleshooting, "Electrical Connectors - Inspect" for details.

2. Perform a 45 N (10 lb) pull test on each of the wires in the ECM connector that are associated with the following connections:
   • P1:48, P1:52, and P1:53 (Unswitched Positive Battery)

   • P1:61, P1:63, and P1:65 (Negative Battery)

   • P1:70 (Keyswitch)

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

4. Check the harness and wiring for abrasions and for pinch points from the battery to the ECM. Also, check the harness and wiring for abrasions and for pinch points from the keyswitch to the ECM.

Expected Result:

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

Results:

• OK - There are no problems with the wiring and/or the connectors. Proceed to Test Step 2.

• Not OK - There is a problem with the connectors or wiring.

  Repair: Repair the connectors or wiring and/or replace the connectors or wiring. Ensure that all of the seals are properly in place and ensure that the connectors are completely coupled.

  STOP

Test Step 2. Check the Battery Voltage at the ECM

1. Disconnect the J1/P1 ECM connector and install a 70-Pin Breakout T.

2. Reconnect the harness.

3. Turn the keyswitch to the ON position.

4. Measure the voltage between P1:52 (Unswitched Positive Battery) and P1:63 (Negative Battery).

5. Measure the voltage between P1:48 (Unswitched Positive Battery) and P1:61 (Negative Battery).

6. Measure the voltage between P1:53 (Unswitched Positive Battery) and P1:65 (Negative Battery).

7. Measure the voltage between P1:70 (Keyswitch) and P1:63 (Negative Battery).

Expected Result:

The measured voltage is between 11.0 VDC and 13.5 VDC for a 12 volt system and between 22.0 VDC and 27.0 VDC for a 24 volt system with no suspected intermittent problems at this time.

Results:

• OK - The ECM is receiving the correct voltage.

  Repair: If an intermittent condition is suspected, refer to Troubleshooting, "Electrical Connectors - Inspect".

  STOP

• Battery voltage is out of range - Proceed to Test Step 3.

• Intermittent or no voltage - Proceed to Test Step 4.

• Keyswitch voltage out of range -

  Repair: Trace the wiring for the keyswitch from the ECM through the keyswitch circuit to the batteries. Find the problem and repair the problem. Check the circuit protection for the circuit and for the wiring.Verify that the repairs eliminate the problem.

  STOP

Test Step 3. Check the Batteries

1. Measure no-load battery voltage at the battery posts.

2. Load test the batteries. Use the 4C-4911 Battery Load Tester. Refer to Special Instruction, SEHS9249, "Use of 4C-4911 Battery Load Tester for 6, 8 and 12 Volt Lead Acid Batteries" and Special Instruction, SEHS7633, "Battery Test Procedure".

Expected Result:

The batteries pass the load test. The measured voltage is the minimum specification for a 12V or 24V system.

Results:

• OK - The batteries are OK.

  Repair: Check the wiring between the batteries and the ECM for shorts.Check the connectors between the batteries and the ECM for moisture and/or corrosion.Repair the wiring and/or the connectors.Verify that the repair eliminates the problem.

  STOP

• Not OK - The battery voltage is low or the battery did not pass the load test.

  Repair: Recharge or replace the faulty batteries. Verify that the repair eliminates the problem.

  STOP

Test Step 4. Use the Bypass Harness for the Electronic Service Tool to Bypass the Engine Wiring

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Batteries give off flammable fumes which can explode. To avoid injury or death, do not strike a match, cause a spark, or smoke in the vicinity of a battery.

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NOTICE
Do Not connect the bypass harness to the battery until the 20 Amp in-line fuse has been removed from the +Battery line. If the fuse is not removed before connection to the battery, a spark may result.

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Illustration 4	g00878173
Bypass harness

Note: This bypass harness is only for test applications. This bypass harness must be removed before the vessel is released to the customer. The bypass harness can be used in order to determine if the cause of the intermittent problem is interruptions in battery power to the ECM or the keyswitch circuit.

1. Turn the keyswitch to the OFF position.

2. Disconnect the J1/P1 ECM connector.

3. Connect a bypass harness between the P1 ECM connector and the ECM.

4. Remove the in-line fuse from the + battery wire of the bypass harness. Connect the + battery wire and the − battery wire directly to the battery posts.

   Note: This bypass directly connects the circuit for the keyswitch to the ECM. The ECM will remain powered until the connection to the unswitched battery line "+" is disconnected from the battery post. Remove the 20 Amp fuse from the in-line fuse holder in order to power down the ECM. Remove the 20 Amp in-line fuse before connecting or disconnecting the bypass harness.

5. Connect the electronic service tool to the data link connector of the bypass harness and verify that communication can be established.

   Note: Disconnect the bypass harness and restore all wiring to the original condition after testing.

Expected Result:

Installing the bypass eliminates the problem.

Results:

• OK - The symptoms disappear when the bypass harness is installed. Also, the symptoms return when the bypass harness is removed. The problem is in the wiring that supplies power to the ECM.

  Repair: Repair the wiring that supplies power to the ECM.Verify that the repair eliminates the problem.

  STOP

• Not OK - The bypass harness did not fix the problem.

  Repair: If the problem still exists, temporarily connect a test ECM.

  1. Use the bypass harness to verify that the repair eliminates the problem.

  2. Reconnect the P1 ECM connector.

  3. If the problem is resolved with the test ECM, reconnect the suspect ECM. If the problem returns with the suspect ECM, replace the ECM.

  4. Verify that the repair eliminates the problem.

  STOP