C32 Marine Engines Electrical Power Supply Circuit - Test Caterpillar


Electrical Power Supply Circuit - Test
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C32 Marine Engines [RENR9303]
ELECTRICAL AND STARTING SYSTEM
BATTERY GP
C32 Marine Engines Electrical Power Supply Circuit - Test

System Operation Description:

Use this procedure to troubleshoot any suspect problems with the electrical power supply.

This procedure covers the 168-02 System Voltage intermittent/erratic diagnostic code.

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

Unswitched battery voltage is supplied to the ECM via the customer connector. The ECM receives the input from the keyswitch via the marine engine control panel and from a remote location. When the ECM detects battery voltage on the keyswitch circuit, the ECM will power up. When battery voltage is removed from the keyswitch circuit, the ECM will power down. The ECM requires the keyswitch to be in the ON position in order to maintain communications with the electronic service tool.

Problems with the power supply to the ECM can occur on either the positive side or the negative side of the battery circuit.

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




Illustration 1g01129612

Schematic for the electrical power supply

Test Step 1. Inspect the Electrical Connectors and the Wiring

  1. Turn the keyswitch to the OFF position.



    Illustration 2g01130307

    Engine components for the electrical power supply

    (1) J61 customer connector

    (2) J1/P1 ECM connectors

    (3) J69 connector for the marine engine control panel (typical location)

  1. Thoroughly inspect connectors (1), (2), and (3). Also inspect the connections for the battery and the connections to the keyswitch. Refer to Troubleshooting, "Electrical Connectors - Inspect" for details.



    Illustration 3g01132902

    P1 terminals that are associated with the electrical power supply

    (P1-48) +Battery

    (P1-52) +Battery

    (P1-53) +Battery

    (P1-61) −Battery

    (P1-63) −Battery

    (P1-65) −Battery

    (P1-67) −Battery

    (P1-70) Keyswitch




    Illustration 4g01136760

    Terminals on the service tool connector that are associated with the electrical power supply

    (A) +Battery

    (B) −Battery




    Illustration 5g01130772

    Terminals on the customer connectors that are associated with the electrical power supply

    (1) +Battery

    (2) −Battery

    (3) −Battery

    (5) +Battery

    (8) +Battery

    (9) −Battery

    (30) Keyswitch




    Illustration 6g01130782

    Terminals on the connector for the marine engine control panel that are associated with the electrical power supply

    (3) Keyswitch

    (8) +Battery

    (10) −Battery

  1. Perform a 45 N (10 lb) pull test on each of the wires that are associated with the electrical power supply.

  1. Check the allen head screw on each ECM connector for the proper torque. Refer to Troubleshooting, "Electrical Connectors - Inspect" for the correct torque values.

  1. 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 of the 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 harness and connectors appear to be OK. Proceed to Test Step 2.

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

    Repair: Repair the wiring and/or the connectors. Replace parts, if necessary. Ensure that all of the seals are properly in place and ensure that the connectors are completely coupled. Verify that the repair eliminates the problem.

    STOP

Test Step 2. Check the Battery Voltage at the P1 Connector

  1. Disconnect the J1/P1 connectors.

  1. Turn the keyswitch to the ON position.

  1. Measure the voltage between the points that are listed in Table 1. Be sure to wiggle the wires in the harnesses as you make each voltage measurement.

    Table 1
    Voltage Measurements for the Electrical Power Supply at the P1 Connector    
    Terminal     Terminal    
    P1-48 (+Battery)     P1-61 (−Battery)    
    P1-52 (+Battery)     P1-63 (−Battery)    
    P1-53 (+Battery)     P1-65 (−Battery)    
    P1-53 (+Battery)     P1-67 (−Battery)    
    P1-70 (Keyswitch)     P1-65 (−Battery)    

Expected Result:

Each voltage measurement 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. Each voltage measurement is steady.

Results:

  • OK - The ECM is receiving the correct voltage.

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

    STOP

  • Not OK - The voltage measurements are not within the specification. Proceed to Test Step 3.

  • Not OK - The voltage measurements are intermittent or there is no voltage. Proceed to Test Step 4.

  • Not OK - The voltage on terminal 70 (keyswitch) is not within the specification.

    Repair: The keyswitch circuit from each keyswitch is protected by a circuit breaker. Verify that the circuit breaker is closed. Trace the wiring for the keyswitch from the ECM through the keyswitch circuit to the batteries. Find the problem and make repairs.Verify that the repairs eliminate the problem.

    STOP

Test Step 3. Check the Batteries

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

  1. 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 measured voltage is at least 11.0 VDC for a 12 volt system and at least 22.0 VDC for a 24 volt system. The battery passes the load test.

Results:

  • OK - The battery is OK.

    Repair: If the problem is still not resolved, there is a problem with the wiring between the battery and the ECM.Repair the wiring and/or the connectors. Replace parts, if necessary. 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 the battery or replace the battery. Verify that the repair eliminates the problem.

    STOP

Test Step 4. Bypass the Engine Wiring With a Bypass Harness

The bypass harness determines if the cause of the problem is in the engine's wiring harness. The bypass harness is only for testing purposes. Remove the bypass harness before you release the vessel to the customer.

    ------ WARNING! ------

    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.

    ----------------------

  1. Turn the keyswitch to the OFF position.

  1. Disconnect the J1/P1 ECM connectors.



    Illustration 7g00878173

    Bypass harness

  1. Connect the bypass harness to the J1 connector.


    NOTICE

    Remove the 20 Amp fuse from the bypass harness before you connect the bypass harness to the battery. A spark may occur if the fuse is not removed before you connect the bypass harness to the battery.


  1. Remove the 20 Amp fuse from the in-line fuse holder of the bypass harness. Connect the +Battery wire and the −Battery wire directly to the battery posts.

    Note: The bypass harness energizes the keyswitch circuit. The ECM will immediately power up when you make the battery connections. The ECM will remain powered until you disconnect the bypass harness from the battery. Remove the 20 Amp fuse from the in-line fuse holder before you disconnect the bypass harness from the battery.

  1. Connect the AVSpare Electronic Technician (ET) to the service tool connector on the bypass harness. Verify that Cat ET can communicate with the ECM.

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

Expected Result:

Installing the bypass harness eliminates the problem.

Results:

  • OK - Installing the bypass harness eliminates the problem. The problem is in the wiring that supplies power to the ECM. There may be a problem with a connector.

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

    STOP

  • Not OK - Installing the bypass harness does not eliminate the problem. There may be a problem with the ECM.

    Repair: It is highly unlikely that the ECM has failed. Perform this entire procedure again. If the problem is still not resolved, replace the ECM. Refer to Troubleshooting, "Replacing the ECM". Verify that the problem is resolved.

    STOP

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