3512B Oil Well Servicing Engine (ADEM III) Caterpillar

Use this procedure to troubleshoot the electrical system if a problem is suspected with the starting system or if one of the diagnostic codes in Table 1 is active.

The ECM has the ability to crank the engine when the circuit for the start/run/stop switch is activated. The crank cycle will continue for the time that is equal to the cycle crank time that has been programmed or the crank cycle will continue until the engine speed reaches the crank terminate speed. If crank terminate speed is not reached before the cycle crank time, the starting motor will deactivate for a time that is equal to the cycle crank time.

This process will repeat for a programmed amount of times (Total Number of Crank Cycles). If the engine does not start, the parameter for "Startup Mode" on the Caterpillar Electronic Technician (ET) will display "OVERCRANK". The engine control will be in an idle state.

The engine can be started manually by using the manual crank switch.

Illustration 1	g01229789
Schematic for the starting motor system

Test Step 1. Inspect the Electrical Connectors and the Wiring

1. Remove electrical power from the ECM.
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   Illustration 2	g01229824
   Location of the J2/P2 ECM connector and the customer connector (typical left side engine view)

2. Thoroughly inspect connectors (1) and (2). Also, thoroughly inspect all of the other connectors for the circuit. Refer to Troubleshooting, "Inspecting Electrical Connectors" for details.
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   Illustration 3	g01229808
   Terminal locations at the P2 ECM connector (P2-6) Crank relay (P2-7) Return for the crank relay

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   Illustration 4	g01229816
   Terminal locations at the customer connector (Terminal 05) Crank relay (Terminal 12) Return for the crank relay

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

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

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 connectors and wiring appear to be 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 for Active Diagnostic Codes

1. Connect Cat ET to the service tool connector.

2. Restore electrical power to the ECM.

3. Turn the start/run/stop switch to the START position.

4. Monitor the active diagnostic code screen on Cat ET. Check and record any active diagnostic codes for the start relay.

   Note: Wait at least 30 seconds in order for the diagnostic codes to become active.

5. Turn the start/run/stop switch to the STOP position.

Expected Result:

No diagnostic codes are active.

Results:

• OK - No diagnostic codes are active, but a problem is suspected in the starting system. Proceed to Test Step 6.

• Not OK - A -5 diagnostic code is active at this time. Proceed to Test Step 4.

• Not OK - A -6 diagnostic code is active at this time. Proceed to Test Step 3.

Test Step 3. Create an Open Circuit at the Start Relay

1. Disconnect the wires from terminal 3 and terminal 4 on the start relay. Ensure that the wires are isolated from engine ground and other sources of electrical power.

2. Turn the start/run/stop switch to the START position.

3. Monitor the active diagnostic code screen on Cat ET. Check and record any active diagnostic codes for the start relay.

   Note: Wait at least 30 seconds in order for the diagnostic codes to become active.

4. Check for a -5 diagnostic code for the start relay.

   Note: Wait at least 30 seconds in order for the diagnostic code to become active.

5. Turn the start/run/stop switch to the STOP position.

Expected Result:

A -5 diagnostic code is now active for the start relay.

Results:

• OK - A -5 diagnostic code became active after disconnecting the wires. A -6 diagnostic code was active before disconnecting the wires.

  Repair: The harness and the ECM are OK. There is a problem with the start relay. Replace the start relay. Verify that there are no active diagnostic codes for the new start relay. Clear any logged diagnostic codes.

  STOP

• Not OK - A -6 diagnostic code remains active. There is a short between the start relay and the ECM. There may be a problem with the ECM. Leave the wires for the start relay disconnected. Proceed to Test Step 5.

Test Step 4. Create a Short at the Connector for the Start Relay

1. Install a jumper wire between terminal 3 and terminal 4 at the start relay.

2. Turn the start/run/stop switch to the START position.

3. Monitor the active diagnostic code screen on Cat ET. Check and record any active diagnostic codes for the start relay.

   Note: Wait at least 30 seconds in order for the diagnostic codes to become active.

4. Turn the start/run/stop switch to the STOP position.

Expected Result:

A -6 diagnostic code is active when the jumper wire is installed. A -5 diagnostic code is active when the jumper wire is removed.

Results:

• OK - A -6 diagnostic code is active when the jumper wire is installed. A -5 diagnostic code is active when the jumper wire is removed. The engine harness and the ECM are OK.

  Repair: The harness and the ECM are OK. There is a problem with the start relay. Replace the start relay. Verify that there are no active diagnostic codes for the new start relay. Clear any logged diagnostic codes.

  STOP

• Not OK - The -5 diagnostic code remains active with the jumper in place. The open circuit is between the ECM and the start relay. There may be a problem with the ECM. Proceed to Test Step 5.

Test Step 5. Test for the Proper Operation of the ECM

1. Fabricate two jumper wires that are long enough to create a test circuit at the ECM connector. Crimp a connector socket to one end of each of the jumper wires.

2. Disconnect the J2/P2 ECM connectors.

3. Remove the wires from terminal locations P2-6 and P2-6at the ECM connector. Install the jumper wires into these terminal locations.

4. Connect the J2/P2 ECM connectors.

5. Check the operation of the ECM by creating an open at the ECM:

   1. Hold the loose end of the jumper wires away from any components in order to create an open circuit condition.

   2. Turn the start/run/stop switch to the START position.

   3. Monitor the active diagnostic code screen on Cat ET. Check and record any active diagnostic codes for the start relay.

      Note: Wait at least 30 seconds in order for the diagnostic codes to become active.

   4. Turn the start/run/stop switch to the STOP position.

6. Check the operation of the ECM by creating a short circuit at the ECM:

   1. Short circuit the loose ends of the jumper wires.

   2. Turn the start/run/stop switch to the START position.

   3. Monitor the active diagnostic code screen on Cat ET. Check and record any active diagnostic codes for the start relay.

      Note: Wait at least 30 seconds in order for the diagnostic codes to become active.

7. Turn the start/run/stop switch to the STOP position.

Restore the wiring to the original configuration.

Expected Result:

A -5 diagnostic code is active when the test circuit is open at the ECM connector. A -6 diagnostic code is active when the jumper wires are shorted at the ECM connector.

Results:

• OK - The ECM is operating properly. The problem is in the wiring between the ECM and the connector for the start relay. Inspect the customer connector for damage or for a loose, corroded connection.

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

  STOP

• Not OK - One of the following conditions exists: The -5 diagnostic code is not active when the wire for the start relay is disconnected. The -6 diagnostic code is not active when the wire jumper is installed.

  Repair: Replace the ECM. Refer to Troubleshooting, "Replacing the ECM". Verify that the problem is resolved.

  STOP

Test Step 6. Check the Voltage to the Start Relay

1. Remove the wire from terminal 1 of the start relay.

2. Ensure that the battery disconnect switch is in the ON position.

3. Measure the voltage between the wire and the engine ground stud.

4. Restore the wiring to the original configuration.

Expected Result:

The voltage measures 24 ± 3 VDC.

Results:

• OK - The voltage measures 24 ± 3 VDC. Proceed to Test Step 7.

• Not OK - The voltage does not measure 24 ± 3 VDC.

  Repair: The problem appears to be in the wiring between the +Battery terminal and the start relay. Repair the connectors or wiring and/or replace the connectors or wiring.

  STOP

Test Step 7. Check the Voltage from the Start Relay to the Start Solenoid

1. Remove the wire from terminal 2 at the start relay.

2. Turn the start/run/stop switch to the START position.

3. Measure the voltage between terminal 2 on the start relay and the engine ground stud.

4. Turn the start/run/stop switch to the STOP position.

5. Restore the wiring to the original configuration.

Expected Result:

The voltage measures 24 ± 3 VDC.

Results:

• OK - The voltage measures 24 ± 3 VDC. Proceed to Test Step 8.

• Not OK - The voltage does not measure 24 ± 3 VDC.

  Repair: Voltage is present at the input terminal to the secondary circuit of the start relay. There are no diagnostic codes for the start relay. Voltage is not present at the output terminal to the secondary circuit of the start relay. Replace the start relay. Verify that the problem is resolved.

  STOP

Test Step 8. Check the Voltage at the Start Solenoid

1. Remove the wire from the positive terminal at the start solenoid.

2. Turn the start/run/stop switch to the START position.

3. Measure the voltage between this wire at the start solenoid and the engine ground stud.

4. Turn the start/run/stop switch to the STOP position.

5. Restore the wiring to the original configuration.

Expected Result:

The voltage measures 24 ± 3 VDC.

Results:

• OK - The voltage measures 24 ± 3 VDC. The problem appears to be in the start solenoid.

  Repair: Verify that you have continuity on the return wire for the start solenoid between the start solenoid and the −Battery. If the return wire for the start solenoid is OK, verify that you have continuity on the +Battery wire for the start solenoid between the start solenoid and the +Battery. If the wiring to the start solenoid is OK, install a new start solenoid.

  STOP

• Not OK - The voltage does not measure 24 ± 3 VDC. The problem is in the wiring between the start relay and the start solenoid.

  Repair: Repair the wiring and/or the connectors. Verify that the problem is resolved.

  STOP