Scan Tool Testing - With Speed Density Update

INSPECTION
A "SCAN" displays manifold pressure in volts. Low pressure (high vacuum) reads a low voltage while a high pressure (low vacuum) reads a high voltage A failure in the MAP sensor circuit should set a Code 33 or 34 and using the chart will find the cause of the problem. A Code 33 may be set if a rough or unstable idle exists.
Chart C-1D can also be used to check Manifold Absolute Pressure (MAP) sensor. Refer to Computers and Controls / System Diagnosis / Procedures / Diagnostic Charts / Chart C-1D. Testing and Inspection