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

Illustration 1	g00616394
Schematic Of The Electronic Governor Relay

The GSC uses the electronic governor relay (EGR) to activate the close-for-rated speed contacts of the electronic governor. When this occurs, the electronic governor increases the engine speed from idle to rated. The electronic governor relay output is rated at 1 amp. The EGR is located within the relay module.

When engine oil pressure is greater than the setpoint for low oil pressure shutdown at idle speed (P14), the GSC activates the EGR. (Also, "K1" is showing on the lower display.) This closes the relay contacts of the EGR and tells the electronic governor to go to rated engine speed.

When engine oil pressure is less than the setpoint for low oil pressure shutdown at idle speed (P14), the GSC does not activate the EGR. (Also, "K1" is not showing on the lower display.) This opens the relay contacts of the EGR and tells the electronic governor to go to idle engine speed.

Note: Whenever the GSC activates or attempts to activate the EGR, "K1" is shown on the lower display. When the EGR is not activated, "K1" is not shown.

The possible cause of a CID 441 FMI 12 fault is:

• An open or shorted coil of the EGR.

The system response to this fault is:

• If a CID 441 fault occurs while the EGR is activated, then the engine speed drops from rated to idle speed (if equipped with an electronic governor).

• If a CID 441 fault occurs while the EGR is not activated, then the engine is able to start and run, but can not reach rated speed (if equipped with an electronic governor).

The GSC treats a CID 441 fault as an alarm fault. Active alarm faults are shown on the display when the alarm codes key is pressed and the ECS switch is in any position except the OFF/RESET position. Clear the fault from the fault log after troubleshooting is complete.

This troubleshooting procedure is for an active or inactive CID 441 fault.

1. Check the status of the diagnostic code (Active/Inactive).

   1. Turn the ECS to OFF/RESET and then turn the ECS to STOP.

   2. Press the alarm codes key.

   3. Observe the upper display. Check that the diagnostic code is showing.

   4. If the diagnostic code is not showing, enter the service mode. View the fault log (OP1). Check that the diagnostic code is showing.

      Expected Result: A CID 441 FMI 12 is showing as a active fault or an inactive fault.

      Results:

      • No - A CID 441 FMI 12 has not occurred. STOP.

      • Yes - A CID 441 FMI 12 is active or inactive. Proceed to 2.

2. Check internal cable of relay module.

   Note: Only open the relay module in a dry environment. If the inspection takes more than twenty minutes replace the desiccant bag in the GSC housing. See Testing And Adjusting, "Relay Module - Replace".

   1. Turn the ECS to OFF/RESET.

   2. Temporarily, remove the relay module from the GSC. See Testing And Adjusting, "Relay Module - Replace".

   3. Check the cable that attaches the relay module to the GSC.

      Expected Result: The cable should be firmly seated in the connector. The clamp should be in place. The cable should not be damaged.

      Results:

      • OK - Reassemble the relay module to the GSC. Proceed to 3.

      • NOT OK - Replace the connector clamp if it is missing. If the cable is damaged, replace the GSC. STOP.

3. Perform a functional check for the OSR.

   1. Turn the ECS to OFF/RESET.

   2. Disconnect all wires from RM-13 and RM-14 of the relay module.

   3. At the relay module, measure the resistance from RM-13 to RM-14. Resistance should be greater than 5000 ohms.

   4. Start the engine. Make sure that the engine oil pressure is greater than the setpoint for low oil pressure shutdown at idle speed (P14).

   5. At the relay module, measure the resistance from RM-13 to RM-14. Resistance should be less than 5 ohms.

      Expected Result: For 3.c, the resistance should be greater than 5000 ohms. For 3.e, the resistance should be less than 5 ohms.

      Results:

      • OK - It is likely that a temporary bad electrical connection existed and this troubleshooting procedure corrected it. Check the electrical connectors, terminals and wiring. See Testing And Adjusting, "Electrical Connector - Inspect". STOP.

      • NOT OK - Either one of the resistance measurements are NOT correct. The relay module is faulty. Replace the relay module. See Testing And Adjusting, "Relay Module - Replace". STOP.