Diagnostic Aids

With ignition switch in ON position and engine stopped, manifold pressure is equal to atmospheric pressure and signal voltage will be high. Comparison of BARO readings from a known good vehicle using same sensor is a good way to check accuracy of suspect sensor. Readings should be same within .4 volt. Code 33 will result if ground circuit is open, MAP signal circuit is shorted to voltage or to 5-volt reference circuit.

Fig 1: Code 33 Schematic (Corvette) MAP Sensor Signal Voltage High

Fig 2: Code 33 Flow Chart (Corvette) MAP Sensor Signal Voltage High