TSB : Diagnostic Aids

Details

With the ignition switch in the ON position and the engine stopped, manifold pressure is equal to atmospheric pressure and the signal voltage will be high. Comparison of the BARO readings from a known good vehicle using the same sensor is a good way to check the accuracy of the suspected sensor. Readings should be the same within +/- .4 volt. Code 33 will result if ground circuit is open or MAP signal circuit is shorted to voltage or to 5-volt reference circuit. Fig 1: Code 33, Schematic, MAP Sensor Signal Voltage High NOTE: For shared sensor reference and shared sensor ground tie-offs, see appropriate diagram in WIRING DIAGRAMS. Fig 2: Code 33, Flow Chart, MAP Sensor Signal Voltage High