Electronic Modular Control Panel II (EMCP II) For PEEC Engines Caterpillar

Illustration 1	g00596452
Schematic For Electrical System

The EMCP II monitors battery voltage in order to protect the EMCP II in case of a problem with the battery or battery charging. The EMCP II operates on a 24 DCV battery system or a 32 DCV battery system. The GSC receives battery voltage from RM-1 of the relay module terminal strip. The GSC measures this voltage. Voltage is received whenever the ECS is in the "START", "AUTO", or "STOP" position.

Note: The GSC does not receive battery power when the ECS is in the OFF/RESET position. The GSC receives power when the contacts "6" and "9" of the ECS are jumpered.

The GSC treats a CID 168 as an alarm fault.

Procedure

This diagnostic code can be caused by the following conditions:

• The battery voltage is less than 32 DCV for a 24 DCV battery system.

• The battery voltage is less than 45 DCV for a 32 DCV battery system.

The setpoint for system voltage (P07) specifies the battery voltage as "0" for 24 volts and "1" for 32 volts. Clear the diagnostic code from the fault log after troubleshooting is complete.

This procedure is used for troubleshooting an active fault or an inactive fault. Active alarm faults are shown on the upper display when the alarm codes key is pressed and the ECS is in any position except the OFF/RESET position. Inactive alarm faults are viewed in the fault log while the operator is in service mode. See Systems Operation, "Fault Log Viewing OP1".

1. Verify the fault.

   1. View the upper display and check for active diagnostic faults for the battery voltage (CID 168 FMI 4).

   2. Enter service mode and check the fault log for inactive diagnostic faults for the battery voltage (CID 168 FMI 4).

      Expected Result: A CID 168 FMI 4 is active.

      Results:

      • No - Battery voltage diagnostic faults, DO NOT EXIST. STOP.

      • Yes - Battery voltage diagnostic faults, DO EXIST. Proceed to 2.

2. Check the voltage.

   1. Turn the ECS to the STOP position.

   2. Note the battery voltage that is showing on the lower display.

   3. Measure the voltage (DCV) between the terminals of the battery.

   4. Measure the voltage (DCV) between RM-1 (B+) and RM-28 (B-) of the terminal strip on the relay module.

      Expected Result: The three voltages (preceding step 2.b, 2.c and 2.d) should be within 2.0 volt of each other.

      Results:

      • OK - All voltages agree (less than 2.0 DCV difference). Proceed to 4.

      • NOT OK - Voltage measured at the batteries does not agree (greater than 2.0 DCV difference) with voltage measured at relay module terminal strip. Proceed to 3.

      • NOT OK - Voltage that is showing on the lower display does not agree (greater than 2.0 DCV difference) with voltage measured at relay module terminal strip. Replace the GSC. See the Testing And Adjusting, "EMCP Electronic Control (Generator Set) - Replace". STOP.

3. Check the harness.

   1. Disconnect the "B+" and "B-" cables from the battery.

   2. Disconnect the "B+" wire from RM-1 and the "B-" wire from RM-28 of the terminal strip on the relay module.

   3. Measure the resistance of each wire. Measure the resistance from the end of the battery to the end of the terminal strip.

      Expected Result: The resistance of a single harness wire should be 5 ohms or less.

      Results:

      • OK - Both resistance measurements are correct. Therefore, an intermittent harness problem is likely. To further check the harness, proceed to Testing And Adjusting, "Electrical Connector - Inspect". STOP.

      • NOT OK - A resistance measurement is greater than 5 ohms. The harness wiring with the incorrect resistance measurement is faulty. Troubleshoot and repair the faulty harness wiring between the battery and the terminal strip on the relay module.

4. Check the system voltage.

   1. Ensure that the engine is off. Measure the system voltage at the battery.

      Expected Result: For 24 volt systems, the battery voltage should be from 24.8 to 29.5 DCV. For 32 volt systems, the battery voltage should be from 33.1 to 39.3 DCV.

      Results:

      • OK - This procedure did not find the cause of the fault. The GSC is an unlikely cause of this diagnostic code. If the batteries or the charging system are suspect, perform "Charging System - Test". See Testing And Adjusting, "Charging System - Test". If an intermittent harness or a terminal problem is suspected, proceed to Testing And Adjusting, "Electrical Connector - Inspect". If the diagnostic code is not discovered, clear the fault log. Check for another occurrence of a CID 168. If a CID 168 persists, replace the GSC. See Testing And Adjusting, "EMCP Electronic Control (Generator Set) - Replace". STOP.

      • NOT OK - The battery voltage is NOT correct. The charging system and/or the batteries are faulty. Perform the "Charging System - Test". See Testing And Adjusting, "Charging System - Test". STOP.