3512B Oil Well Servicing Engine (ADEM III) Caterpillar

Use this procedure to troubleshoot the electrical system if a problem is suspected with the power to the engine's Electronic Control Module (ECM) or if any one of the diagnostic codes in Table 1 is active or easily repeated. Refer to Troubleshooting, "Event Code List" for the default conditions for event codes.

To reduce resistance in the wiring harness, there are two isolated power connections to the ECM. The connections must be complete in order to ensure proper engine operation. There is a constant power supply to the ECM when the engine is shutdown. In order to shut off the power to the ECM, the main power must be disconnected.

The engine will begin the start-up cycle when the following conditions exist:

• The ECM detects battery voltage at the keyswitch on P1-70.

• The Start/Run/Stop Switch is activated.

Illustration 1	g01227331
Typical schematic for the electrical power supply

Test Step 1. Inspect the Electrical Connectors and the Wiring

1. Remove electrical power from the ECM.
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   Illustration 2	g01227322
   Location of the components for the electrical power supply (typical left side engine view) (1) Air shutoff solenoid (2) Customer connector (3) J1/P1 ECM connector (4) J2/P2 ECM connector

2. Thoroughly inspect connectors (2), (3), and (4). Also, thoroughly inspect the terminal connections at the air shutoff mechanisms.

   Refer to Troubleshooting, "Inspecting Electrical Connectors" for details.

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   Illustration 3	g01227424
   P1 ECM connector (P1-5) Digital return (P1-21) Start/Run/Stop input 1 (P1-22) Start/Run/Stop input 2 (P1-23) Emergency stop signal "C" (P1-28) Emergency stop signal "D" (P1-52) +Battery (P1-53) +Battery (P1-55) +Battery (ECM) (P1-56) Air shutoff (NO) (P1-63) −Battery (P1-65) −Battery (P1-70) Keyswitch

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   Illustration 4	g01227426
   P2 ECM connector (P2-13) Air shutoff

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

4. Check the allen head screw for each ECM connector for the proper torque. Refer to Troubleshooting, "Inspecting Electrical Connectors" for the correct torque value.

5. 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 are free of corrosion, of abrasion, and of pinch points.

Results:

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

• Not OK - There is a problem in the connectors and/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.

  Verify that the repair eliminates the problem.

  STOP

Test Step 2. Check the Battery Voltage

1. Turn the main disconnect switch to the OFF position.

2. Measure no-load voltage at the battery posts. Refer to Systems Operation/Testing and Adjusting for the proper procedures to check the batteries.

3. 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 no-load voltage at the batteries is at least 23.5 VDC, and the batteries pass the load test.

Results:

• OK - The no-load voltage at the batteries is at least 23.5 VDC, and the batteries pass the load test. Proceed to Test Step 3.

• Not OK - The no-load voltage at the batteries is less than 23.5 VDC, and/or the batteries fail the load test.

  Repair: The batteries are causing the problem. The problem may be related to a problem with the alternator. Recharge the batteries or replace the batteries. Verify that the original condition is resolved. Refer to Systems Operation/Testing and Adjusting for information on the charging system.

  STOP

Test Step 3. Check the Voltage at the ECM Connector

1. Disconnect the J1/P1 ECM connector.

2. Wiggle the harness during the following test steps in order to find an intermittent condition.

   1. Measure the voltage between P1-52 (unswitched +Battery) and P1-63 (−Battery).

   2. Measure the voltage between P1-53 (unswitched +Battery) and P1-65 (−Battery).

   3. Measure the voltage between P1-70 (keyswitch) and P1-63 (−Battery).

Expected Result:

The voltage is within ± 1 VDC from the voltage that was measured at the battery terminals.

Results:

• OK - The ECM is receiving the correct voltage.

  Repair: There may be an intermittent electrical problem that is causing the problem. If an intermittent condition is suspected, refer to Troubleshooting, "Inspecting Electrical Connectors".

  STOP

• Not OK - The voltage is not within ± 1 VDC from the voltage that was measured at the battery terminals. Proceed to Test Step 4.

Test Step 4. Check the Voltage at the Customer Connector

1. Disconnect the customer connector.

2. Wiggle the harness during the following test steps in order to find an intermittent condition.

   1. Measure the voltage between terminal t1 (unswitched +Battery) and terminal 34 (− Battery).

   2. Measure the voltage between terminal 2 (unswitched +Battery) and terminal 35 (− Battery).

   3. Measure the voltage between terminal 27 (keyswitch) and terminal 34 (− Battery).

Expected Result:

The voltage is within ± 1 VDC from the voltage that was measured at the battery terminals.

Results:

• OK - The voltage is correct at the customer connector.

  Repair: The problem is in the wiring and/or connectors between the customer connector and the ECM. Use continuity checks in order to find the open or short in the wiring harness.

  STOP

• Not OK - The voltage is not within ± 1 VDC from the voltage that was measured at the battery terminals. The voltage is not correct at the customer connector.

  Repair: There is an open circuit or excessive resistance in the wiring or connections between the batteries and the customer connector. Verify that the battery disconnect switch is in the ON position. Verify that the connection for the engine ground is clean and tight. Repair the connectors or wiring and/or replace the connectors or wiring.

  STOP