Diagnostic Aids

Code 66 sets when signal voltage falls outside the normal possible range of the sensor and is not due to a refrigerant system problem. If problem is intermittent, check for opens or shorts in harness or poor connections.

Fig 1: Code 66 Schematic (3.4L (VIN S)) Low A/C Charge

Fig 2: Code 66 Diagnostic Flow Chart (3.4L (VIN S)) Low A/C Charge