3512C and 3516C Engines 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 Engine Control Switch (ECS) is placed in the START position. After the ECS is placed in the START position, the ECM will begin the prelube cycle. The ECM will send an engine start signal to terminal BH of the customer connector after the prelube cycle is complete. The customer's engine start signal will return on terminal BJ of the customer connector. The signal is then sent to terminal 10 of the G-C6 connector on the "Marine Power Display (MPD)" panel.

If a "Starter Select Switch" is installed in the MPD panel, the switch can be set to use either the electric starting motors or the air starting motors. If electric starting motors are installed on the engine, the starting motor relays "SMMS1" and "SMMS2" will be energized. If air starting motors are installed on the engine, the air start solenoids will be energized. If a "Starter Select Switch" is not installed in the MPD panel, the start signal is routed from TB-8 to TB-7. The signal from TB-7 is wired to the starting system. 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.

Note: The prelube cycle can be disabled by setting the duration of the prelube cycle to 0.

This process will repeat for a programmed amount of times "Total Number of Crank Cycles". If the engine does not start, Caterpillar Electronic Technician (ET) will display "OVERCRANK". The engine control will be in an idle state. The process can be restarted by turning the ECS to the OFF/RESET position. Next, turn the ECS to the STOP position. Then turn the ECS to the START position.

The engine can be manually started by using the "crank override switch" which is located on the inside of the instrument panel.

Illustration 1	g01313474
Typical example

Illustration 2	g01242365
P2 ECM connector (P2-6) Starter drive (+) (P2-7) Return (-)

Illustration 3	g01242366
Customer connector (Terminal BH) Start signal from ECM (Terminal BJ) Start signal from customer

Illustration 4	g01234146
Location of ECM connectors

Test Step 1. Inspect Electrical Connectors and Wiring

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

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

3. Thoroughly inspect the ECM connectors J1/P1 and J2/P2. Inspect all of the other connectors. Refer to 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 allen head screw on each ECM connector for the proper torque. Refer to Troubleshooting, "Inspecting Electrical Connectors" for the correct torque values.

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

Results:

• OK - The connectors and wiring are OK. 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. Attempt to Start the Engine

1. Turn the ECS to the STOP position.

2. Connect Cat ET to the service tool connector.

3. Observe the "startup mode" parameter on the Cat ET status screen.

4. Turn the ECS to the START position. Continue monitoring the "startup mode" parameter on the Cat ET status screen as the engine cranks.

   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.

Expected Result:

The status screen for the "startup mode" parameter displays "CRANK". The engine cranks.

Results:

• OK - The "startup mode" parameter on the status screen on Cat ET displays "CRANK". The engine cranks.

  Repair: The problem may be intermittent. If the problem is intermittent, refer to Troubleshooting, "Inspecting Electrical Connectors".

  STOP

• Not OK - Engine Doesn't Crank - The "startup mode" parameter on the status screen on Cat ET displays "CRANK". The engine will not crank. Proceed to Test Step 3.

• Not OK - Status Screen - The "startup mode" parameter on the status screen on Cat ET does not display "CRANK".

  Repair: Refer to Troubleshooting, "Engine Control Switch (ECS)".

  STOP

Test Step 3. Check the Start Signal at the Customer Connector

1. Remove wire F701 from terminal BJ on the customer connector. Connect one end of a voltmeter to the −Battery terminal. Connect the other end of the voltmeter to terminal BJ.

2. Turn the ECS to the START position.

3. Monitor the voltage on the voltmeter.

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

5. Reconnect all wires.

Expected Result:

The voltage is 24 ± 3 VDC.

Results:

• OK - The voltage is 24 ± 3 VDC. Proceed to Test Step 5.

• Not OK - The voltage is not 24 ± 3 VDC. Proceed to Test Step 4.

Test Step 4. Check the Start Signal at the ECM

1. Disconnect the ECM connector J2/P2.

2. Remove wire G701 from the ECM connector P2-6. Install a wire jumper into P2-6.

3. Reconnect the ECM connector J2/P2.

4. Connect one end of a voltmeter to the −Battery terminal. Connect the other end of the voltmeter to the wire jumper in P2-6.

5. Turn the ECS to the START position.

6. Monitor the voltage on the voltmeter.

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

8. Remove the wire jumper and replace all wires.

Expected Result:

The voltage is 24 ± 3 VDC.

Results:

• OK - The voltage is 24 ± 3 VDC.

  Repair: Check wire G701 for continuity between ECM connector P2-6 and terminal BH of the customer connector. If necessary, repair the wire. If wire G701 is OK, repair the wiring or devices on the customer's side of the customer connector.

  STOP

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

  Repair: Check the electrical power to the ECM. Refer to Troubleshooting, "Electrical Power Supply".

  Verify that the engine prelube is operating correctly. Refer to Troubleshooting, "Prelubrication System".

  If the above systems are operating correctly, the problem may be in the ECM. Refer to Troubleshooting, "Replacing the ECM".

  STOP

Test Step 5. Check the Start Signal from the MPD Panel

1. If an electric starting system is installed on the engine, perform the following step.

   1. Remove wire E701 from terminal 9 of connector "G-C6" at the MPD panel. Connect one end of a voltmeter to the −Battery terminal. Connect the other end of the voltmeter to terminal G-C6-9.

2. If an air starting motor system is installed on the engine, perform the following step.

   1. Remove wire G701 from terminal 13 of connector "G-C6" at the MPD panel. Connect one end of a voltmeter to the −Battery terminal. Connect the other end of the voltmeter to terminal G-C6-13.

3. Turn the ECS to the START position.

4. Monitor the voltage on the voltmeter.

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

6. Reconnect all wires.

Expected Result:

The voltage is 24 ± 3 VDC.

Results:

• OK - Electric starting system - The voltage is 24 ± 3 VDC on terminal 9 of connector "G-C6". Proceed to Test Step 6.

• OK - Air starting motor system - The voltage is 24 ± 3 VDC on terminal 13 of connector "G-C6". Proceed to Test Step 12.

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

  Repair: Verify that 24 ± 3 VDC is present on terminal 10 of connector "G-C6" at the MPD panel. If voltage is not present on terminal 10 of connector "G-C6" at the MPD panel, repair the wire F701 between terminal 10 and terminal BJ of the customer connector.

  If voltage is present on terminal 10 of connector "G-C6" at the MPD panel, repair the wiring between terminal 10 of connector "G-C6" at the MPD panel and either terminal 9 or terminal 13 of connector "G-C6" at the MPD panel.

  STOP

Test Step 6. Check the Start Signal from the Power Distribution Panel

1. Remove wire E701 from the engine side of terminal f of connector "P-C1" at the power distribution panel. Connect one end of a voltmeter to the −Battery terminal. Connect the other end of the voltmeter to wire E701.

2. Turn the ECS to the START position.

3. Monitor the voltage on the voltmeter.

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

5. Reconnect all wires.

Expected Result:

The voltage is 24 ± 3 VDC.

Results:

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

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

  Repair: Repair the wire E701 between terminal 9 of connector G-C6 on the MPD panel and terminal f of connector "P-C1" on the power distribution panel.

  STOP

Test Step 7. Check the Voltage from "SMMS1" and "SMMS2"

1. Remove wire 304 from the engine side of terminal O of connector "P-C2" at the power distribution panel. Connect one end of a voltmeter to the −Battery terminal. Connect the other end of the voltmeter to terminal O of connector "P-C2".

2. Turn the ECS to the START position.

3. Monitor the voltage on the voltmeter.

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

5. Remove wire 314 from the engine side of terminal R of connector "P-C2" at the power distribution panel. Connect one end of a voltmeter to the −Battery terminal. Connect the other end of the voltmeter to terminal R of connector "P-C2".

6. Turn the ECS to the START position.

7. Monitor the voltage on the voltmeter.

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

9. Reconnect all wires.

Expected Result:

The voltage is 24 ± 3 VDC.

Results:

• OK - The voltage is 24 ± 3 VDC. Proceed to Test Step 11.

• Not OK - The voltage is not 24 ± 3 VDC. Proceed to Test Step 8.

Test Step 8. Check the Voltage at the Coil of "SMMS1" and the Coil of "SMMS2"

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

2. Remove wire G701 from terminal 3 of "SMMS1" and from terminal 3 of SMMS2.

3. Connect a voltmeter between wire G701 and engine ground.

4. Turn the ECS to the START position.

5. Monitor the voltage on the voltmeter.

6. Turn the ECS to the STOP position.

7. Reconnect all wires.

Expected Result:

The voltage is 24 ± 3 VDC.

Results:

• OK - The voltage is 24 ± 3 VDC. Proceed to Test Step 9.

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

  Repair: Repair the wire G701 between the SMMS switches and terminal f of connector "P-C1" on the power distribution panel.

  STOP

Test Step 9. Check the Voltage across the Coil of "SMMS1" and across the Coil of "SMMS2"

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

2. Connect a voltmeter across the coil of "SMMS1". Connect the voltmeter between terminal 4 and terminal 3 of "SMMS1".

3. Turn the ECS to the START position.

4. Monitor the voltage on the voltmeter.

5. Repeat the above steps for "SMMS2".

6. Turn the ECS to the STOP position.

Expected Result:

The voltage is 24 ± 3 VDC.

Results:

• OK - The voltage is 24 ± 3 VDC.

  Repair: Verify that 24 ± 3 VDC is present on terminal 1 of "SMMS1" or on terminal 1 of "SMMS2". If voltage is not present on terminal 1 of "SMMS1" or on terminal 1 of "SMMS2", check the wire A291 between terminal 1 of the starter magnetic switches and the "Starter and Alternator" breaker. Verify that the "Starter and Alternator" breaker is functioning properly.

  If voltage is present on terminal 1, proceed to Test Step 10.

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

  Repair: The problem is in the wire G229 between terminal 4 of "SMMS1" or "SMMS2" and the breaker for the secondary ECM. Check the wire G229 for continuity between terminal 4 of "SMMS1" or "SMMS2" and the breaker for the secondary ECM. Repair the wire or replace the wire.

  STOP

Test Step 10. Check the Voltage from the Starting Motor Magnetic Switch(s)

1. Remove wire 314 from terminal 2 of the SMMS2 switch. Connect one end of a voltmeter to the −Battery terminal. Connect the other end of the voltmeter to terminal 2 of "SMMS2".

2. Turn the ECS to the START position.

3. Monitor the voltage on the voltmeter.

4. Turn the ECS to the STOP position.

5. Remove wire 304 from terminal 2 of the SMMS1 switch. Connect one end of a voltmeter to the −Battery terminal. Connect the other end of the voltmeter to terminal 2 of "SMMS1".

6. Turn the ECS to the START position.

7. Monitor the voltage on the voltmeter.

8. Turn the ECS to the STOP position.

9. Reconnect all wires.

Expected Result:

The voltage is 24 ± 3 VDC.

Results:

• OK - The voltage is 24 ± 3 VDC.

  Repair: Repair the wire 314 between terminal 2 of "SMMS2" and terminal R of connector "P-C2" or repair the wire 304 between terminal 2 of "SMMS1" and terminal O of connector "P-C2". Repair the wires or replace the wires.

  STOP

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

  Repair: Replace either "SMMS2" or "SMMS2".

  STOP

Test Step 11. Check the Voltage at the Starting Motor

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

2. Remove wire 314 from terminal S of the starting motor. Connect one end of a voltmeter to the −Battery terminal. Connect the other end of the voltmeter to wire 314.

3. Turn the ECS to the START position.

4. Monitor the voltage on the voltmeter.

5. Turn the ECS to the STOP position.

6. Remove wire 304 from terminal S of the starting motor. Connect one end of a voltmeter to the −Battery terminal. Connect the other end of the voltmeter to wire 304.

7. Turn the ECS to the START position.

8. Monitor the voltage on the voltmeter.

9. Turn the ECS to the STOP position.

Expected Result:

The voltage is 24 ± 3 VDC.

Results:

• OK - The voltage is 24 ± 3 VDC. The problem appears to be in the starting motor.

  Repair: Install a new starting motor. Verify that the problem is no longer present.

  STOP

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

  Repair: The problem is in the wire 314 between the starting motor and terminal R of connector "P-C2" or in the wire 304 between the starting motor and terminal O of connector "P-C2". Repair the wires or replace the wires.

  STOP

Test Step 12. Check the Voltage at the Right Hand Air Start Solenoid or at the Left Hand Air Start Solenoid

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

2. Disconnect the connector at the air start solenoid.

3. Measure the voltage between the terminals at the connector for the air start solenoid.

4. Turn the ECS to the START position.

5. Monitor the voltage on the voltmeter.

6. Turn the ECS to the STOP position.

Expected Result:

The voltage is 24 ± 3 VDC.

Results:

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

  Repair: Install a new air start solenoid. Verify that the problem is no longer present.

  STOP

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

  Repair: The problem is in the wire G701 between the connector for the air start solenoid and terminal 9 of connector "G-C6" of the MPD panel or in wire G229 between the connector for the air start solenoid and the ECM. Repair the wires or replace the wires.

  STOP