G3412C, G3508, G3512 and G3516 Engines Status Control Module Caterpillar

Use this procedure if the engine does not crank. Also use this procedure if the engine shuts down immediately after starting.

Note: The engine must be equipped with an electric starting motor.

Test Step 1. Inspect Electrical Connectors and Wiring

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

2. Thoroughly inspect all of the connectors that are associated with the circuit.

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

• Not OK - There is a problem with 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. Start the Engine

1. Turn the main disconnect switch to the ON position and start the engine. View the engine "Status Control Module (SCM)".

Expected Result:

The engine is running. There were no active fault indicators.

Results:

• OK - The engine is running. There were no active fault indicators.

  Repair: The problem is no longer present. If the problem is intermittent, inspect the electrical connectors and wiring.If necessary, repair the connectors or wiring and/or replace the connectors or wiring.Verify that the repair eliminates the problem.

  STOP

• Not OK - The engine does not crank. The SCM shows a blank screen, regardless of the position of the "Engine Control Switch (ECS)". Proceed to Test Step 3.

• Not OK - The engine does not crank. All of the fault indicators are illuminated.

  Repair: Proceed to Troubleshooting, "Engine Shutdown Unexpected and All Fault Indicators Are Flashing".

  STOP

• Not OK - The engine does not crank. A fault indicator(s) is illuminated.

  Repair: Proceed to the appropriate diagnostic procedure in Troubleshooting.

  STOP

• Not OK - The engine does not crank. There are no fault indicators. Allow the "CB2" to cool down for five minutes. Proceed to Test Step 4.

Test Step 3. Check the Voltage at the SCM

1. Turn the ECS to the STOP position.

2. Measure the voltage between terminal 1 and terminal F at the SCM.

   Note: Place the positive meter lead on terminal F and place the negative meter lead on terminal 1.

Expected Result:

The voltage should be between 15 VDC and 45 VDC. The polarity is correct.

Results:

• OK - The voltage is between 15 VDC and 45 VDC.

  Repair: Replace the SCM.

  STOP

• NOT OK - The voltage is below 15 VDC. The polarity is correct.

  Repair: Measure the voltage at the battery posts. Check the wiring and/or connectors between the SCM and the battery.Repair the connectors or wiring and/or replace the connectors or wiring. Replace the battery, if necessary.Verify that the repair eliminates the problem.

  STOP

• NOT OK - The polarity is not correct. Correct any improper connections in the wiring. Proceed to Test Step 4.

Test Step 4. View the Battery Voltage Displayed on the SCM

1. View the battery voltage displayed on the SCM.

Expected Result:

The voltage is above 20 VDC.

Results:

• OK - The voltage is above 20 VDC. Proceed to Test Step 5.

• NOT OK - The voltage is less than 20 VDC.

  Repair: Repair the connectors or wiring and/or replace the connectors or wiring. Replace the battery, if necessary.Verify that the repair eliminates the problem.

  STOP

Test Step 5. Check the Starting Circuit

1. Momentarily connect a wire between terminal 25 and the +Battery terminal at the SCM.

Expected Result:

The engine cranks.

Results:

• OK - The engine cranks. Proceed to Test Step 6.

• NOT OK - The engine does not crank.

  Repair: Proceed to Testing and Adjusting, "Starting Motor Magnetic Switch - Test".Troubleshoot the pinion solenoid and troubleshoot the starting motor. If necessary, repair components or replace components.Verify that the repair eliminates the problem.

  STOP

Test Step 6. Check the Voltage at the SCM

1. Turn the ECS to the MANUAL/START position.

2. Measure the voltage between terminal 25 and the −Battery at the SCM.

3. Measure the voltage between terminal W and the −Battery at the SCM.

4. Measure the voltage between the +Battery and the −Battery at the SCM.

Expected Result:

The +Battery voltage is greater than 20 VDC.

Results:

• OK - The +Battery voltage is greater than 20 VDC.

  Repair: The problem is no longer present. If the problem is intermittent, inspect the electrical connectors and wiring.

  STOP

• NOT OK - The +Battery voltage checks are all less than 20 VDC.

  Repair: Repair the connectors or wiring and/or replace the connectors or wiring. If necessary, replace the battery.Verify that the repair eliminates the problem.

  STOP

• NOT OK - The +Battery voltage is less than 20 VDC on terminal 25.

  Repair: Troubleshoot the starting motor relay. Proceed to Testing and Adjusting, "Relay Module - Test".

  STOP

• NOT OK - The +Battery voltage is less than 20 VDC on terminal 25. The +Battery voltage is less than 20 VDC on terminal W. The +Battery voltage is greater than 20 VDC.

  Repair: Check the F8 fuse.Check the connectors or wiring. If necessary, replace parts or repair parts.Verify that the repair eliminates the problem.

  STOP