Marine Multi-Station Control System Caterpillar

The voltage to the PCP is below normal or shorted low.

Troubleshooting:

This procedure tests whether proper voltage is supplied to the PCP by the multi station control system (MSCS). Use this procedure if there is an active CID 1815 FMI 04 Control System Low Voltage diagnostic code or if you suspect that there is a problem with the electrical battery supply to the PCP.

The battery connections for the multi station control system come into the marine junction box (MJB) on the 5/16 inch terminal posts that are located on the bottom of the marine junction box. The battery voltage is then routed through the appropriate circuit protection and then out through the various connectors to power the following items:

• Displays

• Keyswitch panel

• The ECM unswitched battery connections

Test Step 1. CHECK THE WIRING AND CONNECTORS.

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Illustration 1	g03325937

1. Ensure that none of the circuit breakers are tripped.

2. Turn the keyswitch OFF.

3. Inspect the battery and the battery connections to the marine junction box.

4. Check the Allen head screw on the ECM and the connectors on the power train control processor (PCP) for the proper torque and attachment.

5. Inspect the harnesses for the following conditions:

   • Corrosion

   • Abrasion

   • Pinch points

   • Incorrect attachment

Expected Result:

All items are in good condition.

Results:

• OK - All items are in good condition. Go to Test Step 2.

• NOT OK - All items ARE NOT in good condition.

  Repair: Repair the items or replace the items.

  After the repair, verify that the diagnostic code is NOT active.

  STOP

Test Step 2. CHECK BATTERY VOLTAGE AT THE BATTERIES.

1. Measure the voltage at the batteries.

Expected Result:

The voltage is between 22 VDC and 27 VDC for a 24 VDC system. The voltage is 11 VDC to 14 VDC for a 12 VDC system.

Results:

• OK - The voltage is correct. Go to Test Step 3.

• NOT OK - The voltage IS NOT correct.

  Repair: There is a problem in the battery charging circuit. If the battery voltage is low, recharge the batteries. If the problem continues, there is a problem in the alternator charging circuit. Refer to Special Instruction, REHS0354, "Charging System Troubleshooting". Repair as required. If the battery voltage is too high there is a problem with the alternator charging circuit. Refer to Special Instruction, REHS0354, "Charging System Troubleshooting". Repair as required.

  STOP

Test Step 3. MEASURE THE VOLTAGE AT THE "MARINE JUNCTION BOX".

1. Measure the voltage at the battery post on the MJB.

Expected Result:

The voltage is between 22 VDC and 27 VDC for a 24 VDC system. The voltage is between 11 VDC and 14 VDC for a 12 VDC system.

Results:

• OK - The voltage is correct.

  Repair: Verify that there is not an auxiliary device, which could drain the battery voltage. Repair as required.

  STOP

• NOT OK - The voltage IS NOT correct. There is a problem in the battery circuit from the batteries to the MJB.

  Repair: Repair as required.

  STOP