Variable Control Relay Module (VCRM)

In addition to these functions, the VCRM performs diagnostic checks of its system. Information on any failure that is detected by the VCRM is sent through the DLC (Data+ and Data- circuits) to the powertrain control module (PCM) This failure data is output as diagnostic trouble codes (DTCs) during EEC-IV Key On/Engine Off On-Board Diagnostic.


VCRM On-board Diagnostic Trouble Code Index









Typical Operating Strategies:



Test 1 Conditions: At idle, A/C ON (pressure switch closed), normal engine temperature.

NOTE: If engine is overheating, refer to Test 2.

Fan control speed will be higher if engine temperature is overheating.










Test 2 Conditions: Engine ON, A/C ON.

^ Fan control should be OFF if vehicle speed is greater than 47mph.

^ Fan control will continue to operate 40 seconds after A/C is turned OFF.

^ If ACP fails, fan control will run on high at all times.














(1)Fan control speed will be higher if ACP pressure is high.