COUPLING 2R7712 - Caterpillar

Conditions Which Generate This Code:This diagnostic code is associated with an electrical system voltage that is above normal. The FMI 03 means that the engine electronic control module (ECM) has determined that the electrical system voltage is above normal.
Illustration 1 g00681915
System Schematic For Battery Voltages On EUI And PEEC EnginesThe EMCP II+ monitors the battery voltage in order to protect the EMCP II+ from a battery problem or from a charging problem. The battery voltage is received from the engine electronic control module (ECM) by the CAT data link. If you receive a CID 168 E diagnostic code, refer to Troubleshooting, " 3500B Generator Set Engines Troubleshooting". The GSC+ treats a CID 168 FMI 3 as an alarm diagnostic code. The threshold for a CID 168 FMI 03 for battery voltage is greater than 32 DCV for 24 volt system. The threshold for a CID 168 FMI 03 for battery voltage is greater than 45 DCV for a 32 volt system.
Table 1
POSSIBLE CAUSES FOR CID 168 DIAGNOSTIC CODES    
The Location that the Diagnostic Code is Displayed On     Diagnostic Code     Battery Voltage Thresholds
(24 Volt System)     Battery Voltage Thresholds
(32 Volt System)    
Engine ECM     CID 168 E 00     The engine is running and the battery voltage is greater than 32 DCV more than two seconds.        
Engine ECM     CID 168 E 01     The engine is not running and the battery voltage is less than 9 DCV for more than two seconds.        
Engine ECM     CID 168 E 02     The engine is not running. The battery voltage is less than 9 DCV for a period of .07 seconds. The battery voltage then returns to 9 DCV (or greater). The other possible diagnostic code cause is that the battery voltage goes below 9 DCV three times in seven seconds.        
GSC+     CID 168 FMI 03         Regardless of engine status, the battery voltage is greater than the P007 limit.    
GSC+     CID 168 FMI 04         Regardless of the engine status, the battery voltage is less than 18 DCV.    The setpoint for the system voltage (P007) specifies the battery voltage.24 - 24 Volt System32 - 32 Volt SystemNote: The GSC+ does not receive battery power when the ECS is in the OFF/RESET position. When contact 6 is connected to one of the contacts (8, 9, 10), the GSC+ receives battery power when the ECS is in the OFF/RESET position. Before beginning this procedure, ensure that the following steps have been performed:
VERIFY THE DIAGNOSTIC CODE.
Make sure that the CID 168 FMI 03 is shown on the display.
Enter service mode.
Turn the ECS to the STOP position.Test Step 1. CHECK THE SYSTEM'S VOLTAGE.
Turn the ECS to the STOP.
Measure the voltage across the battery terminals.Expected Result:For a 24 volt system, the voltage should be between 24.8 DCV and 29.5 DCV. For a 32 volt system, the voltage should be between 33.1 DCV and 39.3